Dear Editor,
we read with great interest the paper from Sallustio et al 1 regarding the use of new thromboaspiration catheter, AXS Catalyst 6 (Stryker Neurovascular, Mountain View, CA, USA), for endovascular treatment (EVT) of large vessel stroke (LVS) with A Direct Aspiration first Pass Technique (ADAPT)2.
In our center, a team composed by 4 vascular interventional radiologists, two physicians with certified experience in stroke treatment and two physicians with large carotid stent experience, and 4 stroke neurologist with large experience in intravenous thrombolysis, started to perform EVT in patients with LVS of anterior or posterior circulation from September 2017.
Given the wide availability of different systems of neurothrombectomy we decided to use AXS Catalyst 6 both for its technical features, as reported by Sallustio et al, both for its lower costs than the others available (6F SOFIA plus catheter, MicroVention, Tustin, CA, USA; the X Penumbra ACE catheters, Penumbra Inc., Alameda, CA, USA).
Between September 2017 and May 2018, 24 patients (72.1 ± 13.2 years old) affected by acute ischemic stroke with LVS underwent to EVT in our center. Median baseline NIHSS was 18 (range: 7-24). Intravenous thrombolysis was used in 5 patients.
The most frequent site of occlusion was the middle cerebral artery (MCA) (70.8%), while in 16.7% of cases was basilar artery. Tandem occlusions occurred in 12.5% of patients and the most frequent stroke etiolo...
Dear Editor,
we read with great interest the paper from Sallustio et al 1 regarding the use of new thromboaspiration catheter, AXS Catalyst 6 (Stryker Neurovascular, Mountain View, CA, USA), for endovascular treatment (EVT) of large vessel stroke (LVS) with A Direct Aspiration first Pass Technique (ADAPT)2.
In our center, a team composed by 4 vascular interventional radiologists, two physicians with certified experience in stroke treatment and two physicians with large carotid stent experience, and 4 stroke neurologist with large experience in intravenous thrombolysis, started to perform EVT in patients with LVS of anterior or posterior circulation from September 2017.
Given the wide availability of different systems of neurothrombectomy we decided to use AXS Catalyst 6 both for its technical features, as reported by Sallustio et al, both for its lower costs than the others available (6F SOFIA plus catheter, MicroVention, Tustin, CA, USA; the X Penumbra ACE catheters, Penumbra Inc., Alameda, CA, USA).
Between September 2017 and May 2018, 24 patients (72.1 ± 13.2 years old) affected by acute ischemic stroke with LVS underwent to EVT in our center. Median baseline NIHSS was 18 (range: 7-24). Intravenous thrombolysis was used in 5 patients.
The most frequent site of occlusion was the middle cerebral artery (MCA) (70.8%), while in 16.7% of cases was basilar artery. Tandem occlusions occurred in 12.5% of patients and the most frequent stroke etiology resulted to be cardioembolic (64%).
Time from stroke onset-to-arterial puncture was 213.5 ± 72.0 min
All procedures of patients with LVS that involved anterior circulation, were performed at first in conscious sedation, while 2 patients with involvement of the posterior circulation was treated under general anesthesia.
After catheterizing the common femoral artery with 8Fr introducer, a long sheath introducer (AXS Infinity LS Stryker Neurovascular, Mountain View, CA, USA) was positioned in the distal common carotid artery, proximal cervical ICA, or V1 segment of the vertebral artery.
Therefore, contrary to Sallustio et al, Catalyst 6 catheter was always advanced to the site of occlusion by creating a triaxial system, over a 0.014” guidewire (Transend Stryker, Neurovascular, Mountain View, CA, USA), and over a dedicated coaxial microcatheter (Offset, Stryker Neurovascular, Mountain View, CA, USA). Microcatheter over guidewire, was carefully advanced as close to the thrombus as possible, avoiding crossing it.
When Catalyst 6 catheter tip was touching the thrombus, guidewire and microcatheter were removed, and aspiration was started using always a dedicated vacuum pump.
When no-flow was obtained from aspiration system, Catalyst 6 catheter was slowly pushed forward, and aspiration continued during catheter removal until blood was obtained in the aspiration line or total removal with additional aspiration from the Infinity LS.
Using this approach, we experienced a median procedural time of 52 minutes (range: 20 min to 169 min) with slightly longer time compared to Sallustio et al, maybe because the use of a triaxial system that, at first, could be unwieldy. As assessable, in relation to the low number of cases, we did not find any differences in the procedural times between procedures performed by the different four vascular interventional radiologists.
During procedures we performed at least 3 attempts at revascularization using ADAPT technique before switching to stent retriever technique with Trevo stent (Stryker Neurovascular, Mountain View, CA, USA). We used stent retrieve technique associated with aspiration only in 2 cases (8.3 %). Time from door to reperfusion was 172.0 ± 45.2 min.
We obtained a successful recanalization (TICI 2b/3) in 21 patients (87.5%). Symptomatic intracranial hemorrhage occurred in 1 patient. Functional independence was obtained in 70.8% and mortality occurred in 3 patients.
Our technical success is comparable to results reported by Sallustio et al, although in a less numerous study population.
In our experience, this triaxial system, composed of AXS Infinity LS, Catalyst 6 and Offset microcatheter, surely facilitates performing EVT even when used by “non-expert thrombectomy performers”.
Offset microcatheter helps intermediate catheter ophthalmic passage, avoiding exaggerated thrusts of the catheter that could cause buckling of Catalyst 6, arterial spasms or dissections. Indeed, no arterial dissections or flow limiting arterial vasospasm were identified among 24 interventions.
However, using a microcatheter it could occur that it be passed through the clot and therefore might result in a rate of distal emboli. In our initial experience, we observed only 1 case of thrombus fragmentation with distal M2 branches embolization, due to passing by Offset microcatheter through the thrombus, resulting in TICI 2b revascularization.
In our experience, Catalyst 6 triaxial ADAPT technique was safe, technically feasible, rapid, and effective in patients with LVS.
In ischemic stroke care, fast reperfusion is essential to improve disability free survival and due to the serious paucity of thrombectomy performers, we believe that continuous development of technology of aspiration catheters and microcatheter may reduce procedure time allowing that the neurothrombectomy procedure may be within the reach of vascular interventional radiologists.
References
1. Sallustio, F. et al. Mechanical thrombectomy of acute ischemic stroke with a new intermediate aspiration catheter: preliminary results. J. Neurointerv. Surg. neurintsurg-2017-013679 (2018). doi:10.1136/neurintsurg-2017-013679
2. Turk, A. S. et al. ADAPT FAST study: a direct aspiration first pass technique for acute stroke thrombectomy. J. Neurointerv. Surg. 6, 260–264 (2014).
The paper by Farzin et al.[1] shows interesting results about measuring porosity of fully expanded flow diverter stents using (photographic) images of the stent being assessed. In their study, authors used 3 different methods and repeated measurements by different observers to assess the porosity of stents. According to their results, the variability when measuring porosity is so large that previous works assessing it should be questioned. On the other hand, they indicate that pore density seems to be more reliable and repeatable. The study highlights the difficulty of measuring such parameter in a controlled in vitro environment. After carefully reading the article, it became clear that the most reproducible way of measuring porosity, from the 3 options studied, was M3 (based on measuring the width and length of the struts and number of struts per reference square). Furthermore, some simple assumptions should improve the results and substantially reduce errors and variability:
1. Wire width: the value for wire width, indicated by the manufacturer, is likely to be more accurate. If this value is no to be trusted, at least in average, then the reproducibility of the manufacturing process could not be trusted. Measuring wire width directly on the images is likely to introduce error as it might be affected by reflection/refraction of light on the wire material and wire coating, as well as lens imperfections or optical aberrations in some cases.
2. Calculating poro...
The paper by Farzin et al.[1] shows interesting results about measuring porosity of fully expanded flow diverter stents using (photographic) images of the stent being assessed. In their study, authors used 3 different methods and repeated measurements by different observers to assess the porosity of stents. According to their results, the variability when measuring porosity is so large that previous works assessing it should be questioned. On the other hand, they indicate that pore density seems to be more reliable and repeatable. The study highlights the difficulty of measuring such parameter in a controlled in vitro environment. After carefully reading the article, it became clear that the most reproducible way of measuring porosity, from the 3 options studied, was M3 (based on measuring the width and length of the struts and number of struts per reference square). Furthermore, some simple assumptions should improve the results and substantially reduce errors and variability:
1. Wire width: the value for wire width, indicated by the manufacturer, is likely to be more accurate. If this value is no to be trusted, at least in average, then the reproducibility of the manufacturing process could not be trusted. Measuring wire width directly on the images is likely to introduce error as it might be affected by reflection/refraction of light on the wire material and wire coating, as well as lens imperfections or optical aberrations in some cases.
2. Calculating porosity per strut: using simple geometrical computations is possible measuring the amount of covered area divided by total area, namely porosity, for the rectangular region enclosed by the extremes of one strut (Figure 1 - https://www.dropbox.com/s/oxmbrbs2kv1fcov/Figure%201.pdf?dl=0). This area is equivalent to half the area of one stent cell (i.e. enclosed by 4 neighbouring struts) and the covered area is the rectangular region diagonal multiplied by the wire width, and then subtracting the overlapping region, called Area_open in Figure 1.
3. Calculating pore density per strut: equivalently, pore density can be computed for each strut. In this scenario, partial struts should not be considered. Each strut accounts for half a pore, then a simple division and transformation on the local porosity will yield a local estimation of pore density, as described in Figure 1.
4. Regional measurements are largely affected by FD shape and viewing angle: the further away from the point perpendicular position to the camera view point the measure is performed, the least reliable the measurement will be. Unavoidably, a reference rectangle will consider a region that is affected by this camera view point change. Under such conditions and without correcting the view angle position, only a small region of the FD nearby the region perpendicular to the camera should be considered. A correction to the proposed parameters, considering the angle between the mesh and the view point, should be considered.
The subject of FD porosity and its relation to aneurysm occlusion is recurrently mentioned the literature but so far this subject has not been properly addressed so far. Despite its relevance and implications in treatment selection and local hemodynamics [2], its computation in vivo has not been largely stuied. The work of Boulliot et al.[3] nicely addresses this matter on stents with multiple visible wires, providing an elegant approach to measuring porosity in treated patients as well as the means to simulate the behavior of flow diverters from their geometrical description. Fernandez et al. also proposed and validated a simulation technique with such capabilities[4]. Current medical imaging modalities (3DRA, Dyna-CT/Exper-CT, CTA) provide a resolution that allows visualizing individual wires in FD stents. The combination of improved imaging resolution, improved visibility of flow diverter wires in X-ray images, advanced imaging and simulation algorithms is likely to allow assessment of porosity and pore density in vivo, in the near future.
Ignacio Larrabide, DSc.
Pladema Institute - CONICET – UNICEN
Tandil, Argentina
Demetriud Lopes, PhD. Dr.
RUSH University Hospital
Chicago, IL, USA
References:
1 Farzin, B., Brosseau, L., Jamali, S., Salazkin, I., Jack, A., Darsaut, T. E., & Raymond, J. (2015). Flow diverters: inter and intra-rater reliability of porosity and pore density measurements. Journal of neurointerventional surgery, 7(10), 734-739.
2 Mut, F., & Cebral, J. R. (2012). Effects of flow-diverting device oversizing on hemodynamics alteration in cerebral aneurysms. American Journal of Neuroradiology, 33(10), 2010-2016.
3 Bouillot, P., Brina, O., Ouared, R., Yilmaz, H., Farhat, M., Erceg, G., ... & Pereira, V. M. (2016). Geometrical deployment for braided stent. Medical image analysis, 30, 85-94.
4 Fernandez, H., Macho, J. M., Blasco, J., San Roman, L., Mailaender, W., Serra, L., & Larrabide, I. (2015). Computation of the change in length of a braided device when deployed in realistic vessel models. International journal of computer assisted radiology and surgery, 10(10), 1659-1665.
I was interested to read the paper by Yamauchi K and colleagues published in J Neurointerv Surg 2017 Sep. Hyperperfusion syndrome after carotid interventions has a low incidence but it can lead to morbidity and mortality. The aim of the authors was to evaluate the usefulness of quantitative DSA for predicting hyperperfusion phenomenon (HPP) after carotid artery stenting and angioplasty. Thirty-three consecutive patients with carotid stenosis treated with carotid artery stenting or angioplasty between February 2014 and August 2016 were included. The cerebral circulation time (CCT) was defined as the difference in the relative time to maximum intensity between arterial and venous regions of interest set on the angiograms. HPP was diagnosed straight after the procedure with qualitative 123I-IMP single-photon emission CT (SPECT). Cut-off points for detecting HPP for preprocedural CCT and periprocedural change of CCT were assessed by receiver operating characteristic analysis using 123I-IMP SPECT as reference standard. Differences between patients with and without HPP were analyzed by Student's t test for continuous variables and Fisher`s exact test for categorical variables. A p value of <0.05 was considered statistically significant. Receiver operating characteristic curve analysis of preprocedural CCT and ΔCCT was performed for the prediction of HPP, with 123I-IMP SPECT as standard of reference. They reported that the optimal cut-off points of preprocedural CCT and c...
I was interested to read the paper by Yamauchi K and colleagues published in J Neurointerv Surg 2017 Sep. Hyperperfusion syndrome after carotid interventions has a low incidence but it can lead to morbidity and mortality. The aim of the authors was to evaluate the usefulness of quantitative DSA for predicting hyperperfusion phenomenon (HPP) after carotid artery stenting and angioplasty. Thirty-three consecutive patients with carotid stenosis treated with carotid artery stenting or angioplasty between February 2014 and August 2016 were included. The cerebral circulation time (CCT) was defined as the difference in the relative time to maximum intensity between arterial and venous regions of interest set on the angiograms. HPP was diagnosed straight after the procedure with qualitative 123I-IMP single-photon emission CT (SPECT). Cut-off points for detecting HPP for preprocedural CCT and periprocedural change of CCT were assessed by receiver operating characteristic analysis using 123I-IMP SPECT as reference standard. Differences between patients with and without HPP were analyzed by Student's t test for continuous variables and Fisher`s exact test for categorical variables. A p value of <0.05 was considered statistically significant. Receiver operating characteristic curve analysis of preprocedural CCT and ΔCCT was performed for the prediction of HPP, with 123I-IMP SPECT as standard of reference. They reported that the optimal cut-off points of preprocedural CCT and change of CCT for predicting HPP were 8.0 s (100% sensitivity, 69% specificity) and 3.2 s (75% sensitivity, 100% specificity), respectively. The study suggested that preprocedural prolongation and greater periprocedural change of CCT are associated with the occurrence of HPP. Periprocedural evaluation of CCT may be useful for predicting HPP.1
However, this result has nothing to do with prediction. First, sensitivity and specificity are among estimates that are used to evaluate the diagnostic accuracy of a single test compared to a gold standard. Moreover, for prediction studies, we need data from two different cohorts or at least from one cohort divided into two to first to develop a prediction model and subsequently validate it. Misleading results are generally the main outcome of research that fails to validate its prediction models. 2-5
It is good to know that association dose not necessarily means prediction. Finally, in prediction studies, we must assess the interactions between important variables. Final results can be impacted dramatically when qualitative interactions are present. 2-5 This means that most of the time, without assessing the interaction terms, prediction studies will mainly produce misleading messages.
Keywords: angiography; angioplasty; stent; prediction; methodological issues
References:
1. Yamauchi K, Enomoto Y, Otani K, et al. Prediction of hyperperfusion phenomenon after carotid artery stenting and carotid angioplasty using quantitative DSA with cerebral circulation time imaging. J Neurointerv Surg. 2017 Sep 2. pii: neurintsurg-2017-013259. doi: 10.1136/neurintsurg-2017-013259. [Epub ahead of print]
2. Rothman KJ, Sander Greenland, Timothy L. Lash. Cohort studies. In: Rothman KJ. Modern Epidemiology, 3rd edition. Baltimore, United States: Lippincott Williams & Wilkins; 2008. P.79-85.
3. Sabour S. Prognostic prediction by liver tissue proteomic profiling in patients with colorectal liver metastases; rule of thumb. Future Oncol. 2017 Jun;13(13):1133-1134.
4. Sabour S. Prediction of preterm delivery using levels of VEGF and leptin in amniotic fluid from the second trimester: prediction rules. Arch Gynecol Obstet. 2015 Apr;291(4):719.
5. Sabour S, Ghassemi F. Predictive value of confocal scanning laser for the onset of visual field loss. Ophthalmology. 2013 Jun;120(6):e31-2.
I read with great interest the meta-analysis by Brinjikji et al.1 which evaluated outcomes after mechanical thrombectomy for acute ischemic stroke by using a balloon guiding catheter (BGC) device. In that study, the authors documented that patients who underwent mechanical thrombectomy with BGC had better clinical and angiographic outcomes than those without BGC. However, there were some issues which should be addressed and discussed.
First, the number of successful recanalizations, shown as 2b/3 of Thrombolysis In Cerebral Infarction (TICI) grade in Fig.3 in the article,1 might be not accurately described. The events of successful recanalization were noted in 113 of 149 in the BGC group and 133 of 189 in the non-BGC group according to Nguyen et al.2 However, the events were presented as 112 of 149 in the BGC group and 135 of 189 in the non-BGC group.1 Accordingly, the forest plot can be changed as in Fig. 1 below. Mechanical thrombectomy using BGC exhibited significantly higher successful recanalizations than did non-BGC use (OR, 1.710; 95% CI: 1.099-2.662). Second, there was no specific explanation for the publication bias of Fig. 4 in the result section.1 Although the authors reported a p value of 0.49 using Egger’s regression, we are not sure what publication bias meant to represent, successful recanalization or clinical outcome or other variables.
In this letter, we made a funnel plot for successful recanalization based on the revised number of events we h...
I read with great interest the meta-analysis by Brinjikji et al.1 which evaluated outcomes after mechanical thrombectomy for acute ischemic stroke by using a balloon guiding catheter (BGC) device. In that study, the authors documented that patients who underwent mechanical thrombectomy with BGC had better clinical and angiographic outcomes than those without BGC. However, there were some issues which should be addressed and discussed.
First, the number of successful recanalizations, shown as 2b/3 of Thrombolysis In Cerebral Infarction (TICI) grade in Fig.3 in the article,1 might be not accurately described. The events of successful recanalization were noted in 113 of 149 in the BGC group and 133 of 189 in the non-BGC group according to Nguyen et al.2 However, the events were presented as 112 of 149 in the BGC group and 135 of 189 in the non-BGC group.1 Accordingly, the forest plot can be changed as in Fig. 1 below. Mechanical thrombectomy using BGC exhibited significantly higher successful recanalizations than did non-BGC use (OR, 1.710; 95% CI: 1.099-2.662). Second, there was no specific explanation for the publication bias of Fig. 4 in the result section.1 Although the authors reported a p value of 0.49 using Egger’s regression, we are not sure what publication bias meant to represent, successful recanalization or clinical outcome or other variables.
In this letter, we made a funnel plot for successful recanalization based on the revised number of events we had corrected. However, the funnel plot showed an asymmetry indicative of possible publication bias. To resolve publication bias in deciding on successful recanalization, we trimmed one study. After correction of the forest plot, the adjusted OR was 1.430 (95% CI: 0.852-2.400), suggesting that there was no significant relationship between BGC use and a higher successful recanalization rate (Fig. 2). We think that heterogeneity across studies, in particular thrombus location, can explain the controversial results. Although we did not have accurate information about thrombus location in the studies, which were conference abstract,3-5 difference in posterior circulation may bias the result. For example, we made an additional forest plot based on published articles including two studies6,7 that were not enrolled in the previous meta-analysis1 (Fig. 3A). Our study also demonstrated a higher successful recanalization rate in the BGC group than in the non-BGC group (OR, 2.324; 95% CI: 1.228-4.396). However, possible publication bias was noted, and adjusted OR, after trimming two studies, was 1.630 (95% CI: 0.870-3.053) (Fig.3B). Consequently, we did subgroup analysis for studies that included only anterior circulation stroke patients. Subgroup analysis revealed that the BGC group exhibited a significantly higher successful recanalization rate without heterogeneity (OR, 3.187; 95% CI: 1.797-5.652, Fig. 4A). In addition, publication bias was not observed via the funnel plot (Fig. 4B) or Egger’s regression (p=0.979). Therefore, we think that clot location should be considered to interpret the results.
Per your comments, when using a BGC, some neurointerventionists including us (JHA and JPJ) can be reluctant to use BGC for patients with difficult arches or have concerns about larger 8Fr or 9Fr groin sheath due to complications. As your conclusion, we hope that further randomized trials can give an answer about the BGC feasibility during mechanical thrombectomy for acute stroke patients.
References
1. Brinjikji W, Starke RM, Murad MH, et al. Impact of balloon guide catheter on technical and clinical outcomes: A systematic review and meta-analysis. J Neurointerv Surg. 2018;10:335-9.
2. Nguyen TN, Malisch T, Castonguay AC, et al. Balloon guide catheter improves revascularization and clinical outcomes with the solitaire device: Analysis of the north american solitaire acute stroke registry. Stroke. 2014;45:141-5.
3. Nguyen TN, Castonguay AC, Nogueira RN, et al. Balloon guide catheter improved clinical outcomes, revascularization, and decreased mortality in Trevo thrombectomy. Analysis of the TREVO Stent Retreiver acute stroke (TRACK) Registry. Presentated at the Society of Vascular Interventional Neurology Conference. 2015
4. Zaidat O, Froehler MT, Aziz-Sulta MA, et al. Influce of balloon, conventional or distal catheters on angigraphic and clinical otucomes in the Stratis Registry. Stroke. 2017
5. Zaidat O, Liebeskind D, Jahan R, et al. Influce of balloon, conventional, or distal catheters on angigraphic and technical otucomes in STRATIS. J Neurointerv Surg. 2016.
6. Lee DH, Sung JH, Kim SU, et al. Effective use of balloon guide catheters in reducing incidence of mechanical thrombectomy related distal embolization. Acta Neurochir (Wien). 2017;159:1671-7.
7. Oh JS, Yoon SM, Shim JJ, et al. Efficacy of balloon-guiding catheter for mechanical thrombectomy in patients with anterior circulation ischemic stroke. J Korean Neurosurg Soc. 2017;60:155-64.
Figure legends
Figure 1. Revised forest plot of successful recanalization events according to the use of a balloon guiding catheter (BGC) during mechanical thrombectomy.
Figure 2. Funnel plots of the unadjusted and adjusted effect estimates after correction of publication bias using the “trim and fill” method for successful recanalization. The white circles indicate individual original studies, and the white diamond is the odds ratio (OR) and 95% confidence interval for the meta-analysis. The data point for imputed studies are highlighted in black, and the pooled effect by the recomputation is the black diamond.
Figure 3. A, Comparisons of mechanical thrombectomy for successful recanalization between the BGC group vs. the non-BGC group, based on published full-text articles. B, Funnel plots of the unadjusted and adjusted effect estimates after correction of publication bias using the “trim and fill” method.
Figure 4. A, Subgroup analysis of successful recanalization between the BGC group vs. the non-BGC group, based on published full-text articles that included only anterior circulation stroke. B, Funnel plots of the publication bias.
TO THE EDITOR: We read with interest the recent paper by Boned and colleagues.1 The authors conclude that “CT perfusion may overestimate final infarct core, especially in the early time window. Selecting patients for reperfusion therapies based on the CTP mismatch concept may deny treatment to patients who might still benefit from reperfusion”. We completely agree with this consideration, mainly when, as in this article, the core volume is assessed according to the classical CT perfusion (CTP) mismatch mean transit time (MTT)/cerebral blood volume (CBV)2 by measuring the lesion on CBV maps generated with a one-phase CT perfusion (CTP) acquisition protocol. In fact, it is well-known that a short CTP scan duration often produces a truncation of the perfusion curves resulting in an overestimation of CBV lesion that can frequently reverse.3 In addition, it has recently been demonstrated that relative cerebral blood flow (CBF) < 30% and time to peak of the residual function (Tmax) > 6 seconds is more reliable than CBV < 2.0 ml/100gr and relative MTT > 145% in identifying infarct core and ischemic penumbra at admission, respectively.4,5 As a consequence, the new CTP mismatch model Tmax/CBF was successfully used to include acute ischemic stroke (AIS) patients in the last trials showing the efficacy of endovascular treatment.6-9 We recently treated with combined intravenous thrombolysis and with mechanical thrombectomy patients imaged within 1.5 hour from symptom onset...
TO THE EDITOR: We read with interest the recent paper by Boned and colleagues.1 The authors conclude that “CT perfusion may overestimate final infarct core, especially in the early time window. Selecting patients for reperfusion therapies based on the CTP mismatch concept may deny treatment to patients who might still benefit from reperfusion”. We completely agree with this consideration, mainly when, as in this article, the core volume is assessed according to the classical CT perfusion (CTP) mismatch mean transit time (MTT)/cerebral blood volume (CBV)2 by measuring the lesion on CBV maps generated with a one-phase CT perfusion (CTP) acquisition protocol. In fact, it is well-known that a short CTP scan duration often produces a truncation of the perfusion curves resulting in an overestimation of CBV lesion that can frequently reverse.3 In addition, it has recently been demonstrated that relative cerebral blood flow (CBF) < 30% and time to peak of the residual function (Tmax) > 6 seconds is more reliable than CBV < 2.0 ml/100gr and relative MTT > 145% in identifying infarct core and ischemic penumbra at admission, respectively.4,5 As a consequence, the new CTP mismatch model Tmax/CBF was successfully used to include acute ischemic stroke (AIS) patients in the last trials showing the efficacy of endovascular treatment.6-9 We recently treated with combined intravenous thrombolysis and with mechanical thrombectomy patients imaged within 1.5 hour from symptom onset with NIHSS > 6, CT ASPECTS > 6, M1 occlusion and good collaterals on multi-phase CT Angiography (mCTA) and a hemispheric hypoperfusion on CTP maps. We analysed the one who achieved an angiographic result of TICI 3 within 3 hours from the onset of symptoms. In all these cases, there was no evidence of neurological deficits at neurological examination and ischemic lesion on non-contrast CT at 48 hours after admission. CTP was acquired with a two-phase imaging protocol. CTP maps were obtained using a commercially available software (Olea Sphere 3.0, Olea Medical, La Ciotat, France). In all the patients, an infarct core was found when we used CBV < 2.0 ml/100mg as a threshold value according to MTT/CBV mismatch. However, when the cut-off value was defined as relative CBF < 30 in agreement with Tmax/CBF mismatch, infarct core resulted substantially reduced in size or disappeared completely. These findings confirm that CTP performed early after stroke can overestimate infarct core since tissue survival thresholds may be instable in this stage and, then, more difficult to be recognized by rigid cut-off values. Nevertheless, our experience confirms that relative CBF < 30 is superior than CBV < 2.0 ml/100gr for detection of irreversible damaged tissue. Moreover, the use of a two-phase acquisition protocol and a fully-automated software allows to avoid data truncation affecting not only CBV but also CBF3 and to generate a reproducible tissue classification. Thus, these tools could represent a promising approach to limit the inaccuracies of CTP, making it more reliable in identifying infarct core at admission. As recently reported,10 the combination with information coming from mCTA could further improve the ability of CTP in predicting tissue fate in AIS patients and, therefore, in the selection of AIS patients for reperfusion therapies.
References
1. Boned S, Padroni M, Rubiera M, et al. Admission CT perfusion may overestimate initial
infarct core: the ghost infarct core concept. NeuroIntervent Surg 2017; 9: 66-9.
2. Wintermark M, Flanders AE, Velthuis B, et al. Perfusion-CT assessment of infarct core and penumbra: receiver operating characteristic curve analysis in 130 patients suspected of acute hemispheric stroke. Stroke 2006;37:979-85.
3. Copen WA, Deipolyi AE, Schaefer PW, et al. Exposing hidden truncation-related errors in acute stroke perfusion imaging. AJNR Am J Neuroradiol 2015; 36: 638-45.
4. Campbell BCV, Christensen S, Levi CR, et al. Cerebral blood flow is the optimal CT perfusion
parameter for assessing infarct core. Stroke 2011; 42: 3435-40.
5.Lin L, Bivard A, PhD; Christopher R. Levi CR, et. al. Comparison of computed tomographic and magnetic resonance perfusion measurements in acute ischemic stroke back-to-back quantitative analysis. Stroke 2014; 45: 1727-32.
6. Campbell BC, Mitchell PJ, Kleinig TJ, et al.. Endovascular therapy for ischemic stroke with perfusion-imaging selection. N Engl J Med 2015; 372: 1009-18.
7. Saver JL, Goyal M, Bonafe A, et al. Stent-retriever thrombectomy after intravenous t-PA vs t-PA alone in stroke. N Engl J Med 2015; 372: 2285-95.
8. Nogueira RG, Jadhav AP, Haussen DC, et al. Thrombectomy 6 to 24 Hours after stroke with a mismatch between deficit and infarct. N Engl J Med 2018; 378: 11-21.
9. Albers GW, Marks MP, Kemp S, et al. Thrombectomy for stroke at 6 to 16 hours with selection by perfusion imaging. N Engl J Med 2018 Jan 24. [Epub ahead of print].
10. d'Esterre CD, Trivedi A, Pordeli P, et al. Regional comparison of multiphase computed tomographic angiography and computed tomographic perfusion for prediction of tissue fate in Ischemic Stroke. Stroke 2017; 48: 939-945.
We read with interest the meta-analysis conducted by our colleague Dr Waleed Brinjikji (1). In the text (section "Limitations", he stated: "Data from the Interest of Direct Aspiration First Pass Technique (ADAPT) for Thrombectomy Revascularization of Large Vessel Occlusion in Acute Ischemic Stroke (ASTER) trial suggest that there were no statistically significant differences in revascularization rates when performing the ADAPT technique compared with using a stent retriever. However, it is unclear at this time whether BGCs were used in this trial."
Nevertheless in our publication of the ASTER trial results (2), we clearly stated in the Results section that a balloon-guide catheter was used to allow proximal flow arrest during stent retriever removal in 92% of patients treated with the stent retriever technique.
1. Brinjikji W, Starke RM, Murad MH, et al. Impact of balloon guide catheter on technical and clinical outcomes: a systematic review and meta-analysis. J Neurointerv Surg 2018;10:335–339.
2. Lapergue B, Blanc R, Gory B, et al. JAMA. 2017;318:443-452.
We read with interest the editorial by Darsaut and colleagues entitled, “PHASES and the natural history of unruptured aneurysms: science or pseudoscience?”[1]. Beginning with references to Aristotle and Pliny the Elder (always impressive), the authors launch a critique of studies of the natural history of unruptured aneurysms. With attention to ISUIA and the PHASES system, the contributors from Quebec call attention to limitations in both prospective and retrospective studies of the risk of rupture and associated risk factors for rupture of intracranial aneurysms. In their view, these imperfect studies are so deeply flawed that they are essentially useless as tools to inform decision-making with patients with unruptured intracranial aneurysms. Ending with the umpteenth call for a randomized trial, the authors create the impression that, for all patients with all kinds, sizes and locations of intracranial aneurysms, clinicians are powerless to use data from the available studies, condensed in the PHASES Score, to guide decision-making.
The PHASES score, developed from a pooled analysis of six prospective cohort studies of patients with unruptured intracranial aneurysms, was designed to use existing natural history data (limited though that may be), to provide some estimate of future rupture risk and to aid in identifying risk factors for rupture that may push clinician and patient past the treatment threshold. Several lines of evidence support the use of PHASES...
We read with interest the editorial by Darsaut and colleagues entitled, “PHASES and the natural history of unruptured aneurysms: science or pseudoscience?”[1]. Beginning with references to Aristotle and Pliny the Elder (always impressive), the authors launch a critique of studies of the natural history of unruptured aneurysms. With attention to ISUIA and the PHASES system, the contributors from Quebec call attention to limitations in both prospective and retrospective studies of the risk of rupture and associated risk factors for rupture of intracranial aneurysms. In their view, these imperfect studies are so deeply flawed that they are essentially useless as tools to inform decision-making with patients with unruptured intracranial aneurysms. Ending with the umpteenth call for a randomized trial, the authors create the impression that, for all patients with all kinds, sizes and locations of intracranial aneurysms, clinicians are powerless to use data from the available studies, condensed in the PHASES Score, to guide decision-making.
The PHASES score, developed from a pooled analysis of six prospective cohort studies of patients with unruptured intracranial aneurysms, was designed to use existing natural history data (limited though that may be), to provide some estimate of future rupture risk and to aid in identifying risk factors for rupture that may push clinician and patient past the treatment threshold. Several lines of evidence support the use of PHASES in the day-to-day management of patients with unruptured intracranial aneurysms.
First, conservative management of selected unruptured intracranial aneurysms, along with attention to risk factors for growth and rupture, such as hypertension and cigarette smoking, is both widespread and valid[2]. Interesting recent retrospective studies have shed light on both the risk of aneurysm enlargement during serial surveillance imaging (overall annual risk of 2-5%) and whether risk of rupture is elevated in patients with enlargement during surveillance (it is, to the tune of an annual risk of rupture of 18.5%) [3-6]. Thus, although treatment of unruptured aneurysms is extensive worldwide, conservative management is widespread also, and methods to inform decision-making in this setting are much needed.
Second, the authors of the editorial take issue with the limitations and imprecision of both ISUIA and PHASES, stating that “PHASES…has never predicted a single event…” and that three large Japanese cohorts “have refuted the ISUIA predictions.” Although Greving and colleagues did indeed use the unfortunate phrase “prediction of risk” in the title of their paper about PHASES, the actual purpose of PHASES (and ISUIA) was to estimate risk, given patient-specific factors, rather than predict risk[7]. The term predict implies a degree of precision that is not realistic in this setting. Rather, estimations of risk, however flawed and imprecise they are, serve to nudge patients and their clinicians toward one direction or another. In the absence of Level I evidence, black and white decision tools are simply not possible. On the other hand, when an accumulation of factors that are associated with growth and rupture are present in an individual patient, this individual may be inclined to seek treatment, even though a precise “prediction” of rupture risk is not possible.
Lastly, the authors conclude their editorial with a spirited call for a randomized trial. However, it is nearly impossible to imagine that a multicenter randomized trial comparing medical management to treatment of unruptured aneurysms could be accomplished in the current environment. Indeed in a previously published assessment of the failed TEAM Trial, the authors outline three compelling reasons for the futility of any attempt at conducting a randomized trial of unruptured aneurysms: 1) Lack of funding support and bureaucratic barriers from scientific agencies (NINDS, CIHR) 2) Physician unwillingness to enter patients in such a trial due to lack of equipoise, and 3) Patient disinterest in trial participation where a desired intervention would be denied[8]. Unless major changes have occurred in bureaucratic and funding processes, physician opinion, and patient desires in the last few years, we agree with the authors prior work on the futility of hoping for such a trial. Furthermore, any serious attempt at a randomized trial would be at risk of suffering the same fate as the ARUBA trial. Strenuous opposition to ARUBA arose long before trial completion. Objection to ARUBA centered on the argument that a randomized trial of treatment of a life-long condition such as brain AVMs, with only 5-year follow-up, could not fairly compare to interventions with very different risk functions over time. A similar study conducted on unruptured intracranial aneurysms would be hampered by identical limitations.
In the absence of a hypothetical “ideal” study, which the hard nature of reality is unlikely to deliver, clinicians and patients must make decisions, and make them today. PHASES while distinctly not an ideal study, provides guidance based on evidence, when an ideal study is unlikely to be accomplished in the foreseeable future.
References
1 Darsaut T, Fahed R, Raymond J. PHASES and the natural history of unruptured aneurysms: science or pseudoscience? J Neurointerventional Surg 2016;:neurintsurg–2016.
2 Thompson BG, Brown RD, Amin-Hanjani S, et al. Guidelines for the management of patients with unruptured intracranial aneurysms: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke 2015;46:2368–2400.
3 Sonobe M, Yamazaki T, Yonekura M, et al. Small Unruptured Intracranial Aneurysm Verification Study: SUAVe Study, Japan. Stroke 2010;41:1969–77. doi:10.1161/STROKEAHA.110.585059
4 Inoue T, Shimizu H, Fujimura M, et al. Annual rupture risk of growing unruptured cerebral aneurysms detected by magnetic resonance angiography. J Neurosurg 2012;117:20–25.
5 Backes D, Vergouwen MD, Groenestege ATT, et al. PHASES score for prediction of intracranial aneurysm growth. Stroke 2015;46:1221–1226.
6 Serrone JC, Tackla RD, Gozal YM, et al. Aneurysm growth and de novo aneurysms during aneurysm surveillance. J Neurosurg 2016;125:1374–82. doi:10.3171/2015.12.JNS151552
7 Greving JP, Wermer MJ, Brown RD, et al. Development of the PHASES score for prediction of risk of rupture of intracranial aneurysms: a pooled analysis of six prospective cohort studies. Lancet Neurol 2014;13:59–66.
8 Raymond J, Darsaut TE, Molyneux AJ. A trial on unruptured intracranial aneurysms (the TEAM trial): results, lessons from a failure and the necessity for clinical care trials. Trials 2011;12:64.
We appreciate the interest shown by Drs. Yao and You (1) in our paper (2) and find it our pleasure to address their concerns.
The first point raised by Drs. Yao and You is that our search strategy missed two articles, namely those of Mortimer et al (2015) (3) and Morgan et al (1996) (4). We would like to reassure Drs. Yao and You that we did screen these articles, and decided against including them in our meta-analysis based on our inclusion criteria. The article by Mortimer et al (2015) (3) describes a patient population where balloon angioplasty, verapamil, and papaverine infusions were used separately or in various combinations. They did not break down their results by the specific intra-arterial vasodilator (IAD) used, and therefore we decided not to include this information. The paper by Morgan et al (1996) (4) describes a patient population which overlapped with that described by the same group in another paper, Morgan et al (2000) (5). We had personally communicated with the authors in 2016 regarding the multiple papers from this group, such as Little et al (1994) (6) and Morgan et al (2000)
(5) that described papaverine infusions for vasospasm. We found out that there were overlaps in these study populations, and that the cohort in the 2000 paper(5) was the most complete. Therefore, only this paper was included in our meta-analysis, while the earlier ones were excluded.
The second suggestion by Drs. Yao and You was to perform a regression ana...
We appreciate the interest shown by Drs. Yao and You (1) in our paper (2) and find it our pleasure to address their concerns.
The first point raised by Drs. Yao and You is that our search strategy missed two articles, namely those of Mortimer et al (2015) (3) and Morgan et al (1996) (4). We would like to reassure Drs. Yao and You that we did screen these articles, and decided against including them in our meta-analysis based on our inclusion criteria. The article by Mortimer et al (2015) (3) describes a patient population where balloon angioplasty, verapamil, and papaverine infusions were used separately or in various combinations. They did not break down their results by the specific intra-arterial vasodilator (IAD) used, and therefore we decided not to include this information. The paper by Morgan et al (1996) (4) describes a patient population which overlapped with that described by the same group in another paper, Morgan et al (2000) (5). We had personally communicated with the authors in 2016 regarding the multiple papers from this group, such as Little et al (1994) (6) and Morgan et al (2000)
(5) that described papaverine infusions for vasospasm. We found out that there were overlaps in these study populations, and that the cohort in the 2000 paper(5) was the most complete. Therefore, only this paper was included in our meta-analysis, while the earlier ones were excluded.
The second suggestion by Drs. Yao and You was to perform a regression analysis to “solve” the heterogeneity. For a methodically sound meta-analysis, heterogeneity is always presumed to exist, as statistical analysis is but one means of measuring it. When statistically significant heterogeneity is found, it should be quantified and accounted for with subgroup and sensitivity analysis, and subsequently potential contributors to it also discussed subjectively. Meta-regression is another step to account for it. Given the relatively small sample sizes and the observational nature of the included studies, we felt a meta-regression would not do justice to the available data, and would be overreaching.
Finally, they note that several of our studies used balloon angioplasty in addition to IADs, which might have significantly influenced our findings of IAD efficacy and safety. This is a valid concern, which we had anticipated and stated in the limitations section of our manuscript that, “IAD and balloon angioplasty were used in combination in many patients, which may confound our results when the aim was to isolate the effects of IADs”(2). During our data abstraction, we noted that most studies did not separately report data for IADs and balloon angioplasty, and often used these in conjunction. In the interest of retaining sufficient sample sizes for our analysis, we were left with no recourse but to accept even those studies that included balloon angioplasty along with IADs.
We would once again like to thank Drs. Yao and You for their interest in our paper, and their insightful questions.
Authors
References
1. Yao ZY, C. Intra-arterial vasodilators for vasospasm following aneurysmal subarachnoid hemorrhage. Journal of Neurointerventional Surgery. 2017.
2. Venkatraman A, Khawaja AM, Gupta S, Hardas S, Deveikis JP, Harrigan MR, et al. Intra-arterial vasodilators for vasospasm following aneurysmal subarachnoid hemorrhage: a meta-analysis. J Neurointerv Surg. 2017.
3. Mortimer AM, Steinfort B, Faulder K, Bradford C, Finfer S, Assaad N, et al. The detrimental clinical impact of severe angiographic vasospasm may be diminished by maximal medical therapy and intensive endovascular treatment. J Neurointerv Surg. 2015;7(12):881-7.
4. Morgan M, Halcrow S, Sorby W, Grinnell V. Outcome of aneurysmal subarachnoid haemorrhage following the introduction of papaverine angioplasty. J Clin Neurosci. 1996;3(2):139-42.
5. Morgan MK, Jonker B, Finfer S, Harrington T, Dorsch NW. Aggressive management of aneurysmal subarachnoid haemorrhage based on a papaverine angioplasty protocol. J Clin Neurosci. 2000;7(4):305-8.
6. Little N, Morgan MK, Grinnell V, Sorby W. Intra-arterial papaverine in the management of cerebral vasospasm following subarachnoid haemorrhage. J Clin Neurosci. 1994;1(1):42-6.
With great interest, we read the article of Venkatraman et al.[1] published in the Journal of NeuroInterventional Surgery recently. They presented a comprehensive picture depicting the effect of intra-arterial vasodilators (IADs) on the vasospasm following aneurysmal subarachnoid hemorrhage. But we were concerned with several questions weakening the reliability and generalization of the meta-analysis.
Firstly , though the detailed including criteria and searching strategy were provided in their meta-analysis, at least two eligible studies2,3 were missed which conformed to their including criteria and unfulfilled the excluding criteria. Two cohort studies of Morgan [2] and Mortimer [3] reported the effects of IADs on vasospasm with documentation of interested events, which should be included in Venkatraman’s analysis. Whether addition of these two studies could change the overall effect of IADs was unclear, but including any eligible study was in accordance with PRISMA principle.
Secondly, owing to the large number of included studies, the heterogeneity was substantial. Venkatraman et al.[1] conducted subgroup and sensitivity analyses, in which the heterogeneity remained significant (most values of I2 greater than 50%). It was rationale to turn to regression analyses in order to find and solve the heterogeneity.
Besides, this article included studies combining IADs with balloon angioplasty, which might overestimate effectiveness of IADs. IADs w...
With great interest, we read the article of Venkatraman et al.[1] published in the Journal of NeuroInterventional Surgery recently. They presented a comprehensive picture depicting the effect of intra-arterial vasodilators (IADs) on the vasospasm following aneurysmal subarachnoid hemorrhage. But we were concerned with several questions weakening the reliability and generalization of the meta-analysis.
Firstly , though the detailed including criteria and searching strategy were provided in their meta-analysis, at least two eligible studies2,3 were missed which conformed to their including criteria and unfulfilled the excluding criteria. Two cohort studies of Morgan [2] and Mortimer [3] reported the effects of IADs on vasospasm with documentation of interested events, which should be included in Venkatraman’s analysis. Whether addition of these two studies could change the overall effect of IADs was unclear, but including any eligible study was in accordance with PRISMA principle.
Secondly, owing to the large number of included studies, the heterogeneity was substantial. Venkatraman et al.[1] conducted subgroup and sensitivity analyses, in which the heterogeneity remained significant (most values of I2 greater than 50%). It was rationale to turn to regression analyses in order to find and solve the heterogeneity.
Besides, this article included studies combining IADs with balloon angioplasty, which might overestimate effectiveness of IADs. IADs worked in coordination with balloon angioplasty, for balloon angioplasty dilated proximal vessel assisting IADs to expand distal vessels. We could not exclude the possibility partial effect on the outcomes was attributable to balloon angioplasty. Similarly, it was reasonable to ascribe many complications to the balloon angioplasty, like vessel perforation.
In all, we would like to congratulate Venkatraman for the great work of meta-analyzing the impact of IADs on the treatment of vasospasm following subarachnoid hemorrhage.
References
1. Venkatraman A, Khawaja AM, Gupta S, et al. Intra-arterial vasodilators for vasospasm following aneurysmal subarachnoid hemorrhage: a meta-analysis. J Neurointerv Surg. 2017.
2. Morgan M, Halcrow S, Sorby W, Grinnell V. Outcome of aneurysmal subarachnoid haemorrhage following the introduction of papaverine angioplasty. J Clin Neurosci. 1996;3(2):139-142.
3. Mortimer AM, Steinfort B, Faulder K, et al. The detrimental clinical impact of severe angiographic vasospasm may be diminished by maximal medical therapy and intensive endovascular treatment. Journal of Neurointerventional Surgery. 2015;7(12):881-887.
We read with great interest the article of Haussen et al. 1 outlining the problem of identifying patients with minor stroke symptoms (low NIHSS) despite proximal vessel occlusion who should undergo thrombectomy. Intension-to-treat analysis showed significantly higher reduction of stroke severity in the primary thrombectomy group compared to the medical group. But more interestingly, per-protocol analysis revealed a high propo...
We read with great interest the article of Haussen et al. 1 outlining the problem of identifying patients with minor stroke symptoms (low NIHSS) despite proximal vessel occlusion who should undergo thrombectomy. Intension-to-treat analysis showed significantly higher reduction of stroke severity in the primary thrombectomy group compared to the medical group. But more interestingly, per-protocol analysis revealed a high proportion of rescue thrombectomies due to neurological deterioration with a clearly time-dependent effect on outcome after the procedure in the medical group. In our opinion, the problem is multidimensional. In proximal vessel occlusion, intravenous thrombolysis combined with thrombectomy is superior to thrombolysis alone. Current guidelines strongly recommend thrombectomy in these patients and not to stop after intravenous thrombolysis 2. Therefore, it is critical to identify ischemic stroke due to proximal vessel occlusion. High stroke severity measured by the NIHSS has been used as a clinical surrogate to detect major vessel occlusion. Fischer et al. reported an NIHSS threshold of 12 to have a positive predictive value of 91% for central occlusion 3. But this approach can be misleading as the NIHSS represents the amount of ischemic tissue, which is influenced by residual blood supply beyond the occlusion, especially by collateral circulation. Good collaterals can lead to a low NIHSS score in stroke with proximal vessel occlusion. Maas et al. showed that higher NIHSS cutoffs to predict major vessel occlusion missed more proximal occlusions, concluding that there was no NIHSS threshold to identify the majority of clinically important occlusive lesions. An NIHSS threshold of 10, for example had only 48% sensitivity 4. Minor stroke severity resulting in a low NIHSS is not uncommon in proximal vessel occlusion. One group identified 23% of patients with NIHSS <8 in a retrospective database search 5. In another population, approx. 90% of patients presenting with an NIHSS <=10 were found to have major vessel occlusion 4. In our opinion, current data indicate that all stroke patients admitted within the therapeutic time window should undergo vascular imaging. Another question is how to treat these patients. Until a few years ago intravenous thrombolysis was given only to patients with a "significant" neurological deficit, commonly defined as an NIHSS of 4 or higher. Today we know that low NIHSS stroke, even without proximal vessel occlusion, has unfavourable long-term outcome and that intravenous thrombolysis seems to be beneficial in this setting 6 with low risk of intracrcanial bleeding 7. In clinical practice, we today concentrate on individual deficits and try to individualize the treatment decision. In patients with central occlusion and NIHSS 2-7, the natural course is also rather unfavourable. Even in this low NIHSS stratum higher stroke severity was significantly associated with discharge into a facility and gait problems 5. The current study adds important knowledge for decision making in this situation as 41% of the medical group deteriorated a few hours after admission, which was likely caused by failure of the collateral system. Those who were "lucky" to suffer fast breakdown of collateral supply had better functional outcome after rescue thrombectomy than those with later failure. For future treatment algorithms, it will be essential to know more about the dynamics of collateral circulation and to develop a strategy to predict their failure. Currently, it is very difficult to make individual treatment decisions in this subset of patients as the thrombectomy procedure itself has a risk of recurrent stroke, vasospasm and subarchnoid hemorrhage 8.
References
1. Haussen DC, Bouslama M, Grossberg JA, et al. Too good to
intervene? Thrombectomy for large vessel occlusion strokes with minimal
symptoms: an intention-to-treat analysis. J Neurointerv Surg Published
Online First: 2 Sep 2016. doi: 10.1136/neurintsurg-2016-012633.
2. Powers WJ, Derdeyn CP, Biller J, et al. 2015 AHA/ASA Focused Update of
the 2013 Guidelines for the Early Management of Patients With Acute
Ischemic Stroke Regarding Endovascular Treatment: A Guideline for
Healthcare Professionals From the American Heart Association/American
Stroke Association. Stroke 2015;46:3020-3035.
3. Fischer U, Arnold M, Nedeltchev K, et al. NIHSS score and
arteriographic findings in acute ischemic stroke. Stroke 2005;36:2121-
2125.
4. Maas MB, Furie KL, Lev MH, et al. National Institutes of Health Stroke
Scale score is poorly predictive of proximal occlusion in acute cerebral
ischemia. Stroke 2009;40:2988-2993.
5. Mokin M, Masud MW, Dumont TM, et al. Outcomes in patients with acute
ischemic stroke from proximal intracranial vessel occlusion and NIHSS
score below 8. J Neurointerv Surg 2014;6:413-417.
6. Greisenegger S, Seyfang L, Kiechl S, et al. Thrombolysis in Patients
With Mild Stroke. Stroke 2014;45:765-769.
7. Strbian D, Piironen K, Meretoja A, et al. Intravenous Thrombolysis for
Acute Ischemic Stroke Patients Presenting with Mild Symptoms. Int J Stroke
2013;8:293-299.
8. Emprechtinger R, Piso B, Ringleb PA. Thrombectomy for ischemic stroke:
meta-analyses of recurrent strokes, vasospasms, and subarachnoid
hemorrhages. Journal of Neurology Published Online First: 20 Jun 2016.
doi: 10.1007/s00415-016-8205-1
Dear Editor,
Show Morewe read with great interest the paper from Sallustio et al 1 regarding the use of new thromboaspiration catheter, AXS Catalyst 6 (Stryker Neurovascular, Mountain View, CA, USA), for endovascular treatment (EVT) of large vessel stroke (LVS) with A Direct Aspiration first Pass Technique (ADAPT)2.
In our center, a team composed by 4 vascular interventional radiologists, two physicians with certified experience in stroke treatment and two physicians with large carotid stent experience, and 4 stroke neurologist with large experience in intravenous thrombolysis, started to perform EVT in patients with LVS of anterior or posterior circulation from September 2017.
Given the wide availability of different systems of neurothrombectomy we decided to use AXS Catalyst 6 both for its technical features, as reported by Sallustio et al, both for its lower costs than the others available (6F SOFIA plus catheter, MicroVention, Tustin, CA, USA; the X Penumbra ACE catheters, Penumbra Inc., Alameda, CA, USA).
Between September 2017 and May 2018, 24 patients (72.1 ± 13.2 years old) affected by acute ischemic stroke with LVS underwent to EVT in our center. Median baseline NIHSS was 18 (range: 7-24). Intravenous thrombolysis was used in 5 patients.
The most frequent site of occlusion was the middle cerebral artery (MCA) (70.8%), while in 16.7% of cases was basilar artery. Tandem occlusions occurred in 12.5% of patients and the most frequent stroke etiolo...
The paper by Farzin et al.[1] shows interesting results about measuring porosity of fully expanded flow diverter stents using (photographic) images of the stent being assessed. In their study, authors used 3 different methods and repeated measurements by different observers to assess the porosity of stents. According to their results, the variability when measuring porosity is so large that previous works assessing it should be questioned. On the other hand, they indicate that pore density seems to be more reliable and repeatable. The study highlights the difficulty of measuring such parameter in a controlled in vitro environment. After carefully reading the article, it became clear that the most reproducible way of measuring porosity, from the 3 options studied, was M3 (based on measuring the width and length of the struts and number of struts per reference square). Furthermore, some simple assumptions should improve the results and substantially reduce errors and variability:
Show More1. Wire width: the value for wire width, indicated by the manufacturer, is likely to be more accurate. If this value is no to be trusted, at least in average, then the reproducibility of the manufacturing process could not be trusted. Measuring wire width directly on the images is likely to introduce error as it might be affected by reflection/refraction of light on the wire material and wire coating, as well as lens imperfections or optical aberrations in some cases.
2. Calculating poro...
I was interested to read the paper by Yamauchi K and colleagues published in J Neurointerv Surg 2017 Sep. Hyperperfusion syndrome after carotid interventions has a low incidence but it can lead to morbidity and mortality. The aim of the authors was to evaluate the usefulness of quantitative DSA for predicting hyperperfusion phenomenon (HPP) after carotid artery stenting and angioplasty. Thirty-three consecutive patients with carotid stenosis treated with carotid artery stenting or angioplasty between February 2014 and August 2016 were included. The cerebral circulation time (CCT) was defined as the difference in the relative time to maximum intensity between arterial and venous regions of interest set on the angiograms. HPP was diagnosed straight after the procedure with qualitative 123I-IMP single-photon emission CT (SPECT). Cut-off points for detecting HPP for preprocedural CCT and periprocedural change of CCT were assessed by receiver operating characteristic analysis using 123I-IMP SPECT as reference standard. Differences between patients with and without HPP were analyzed by Student's t test for continuous variables and Fisher`s exact test for categorical variables. A p value of <0.05 was considered statistically significant. Receiver operating characteristic curve analysis of preprocedural CCT and ΔCCT was performed for the prediction of HPP, with 123I-IMP SPECT as standard of reference. They reported that the optimal cut-off points of preprocedural CCT and c...
Show MoreI read with great interest the meta-analysis by Brinjikji et al.1 which evaluated outcomes after mechanical thrombectomy for acute ischemic stroke by using a balloon guiding catheter (BGC) device. In that study, the authors documented that patients who underwent mechanical thrombectomy with BGC had better clinical and angiographic outcomes than those without BGC. However, there were some issues which should be addressed and discussed.
Show MoreFirst, the number of successful recanalizations, shown as 2b/3 of Thrombolysis In Cerebral Infarction (TICI) grade in Fig.3 in the article,1 might be not accurately described. The events of successful recanalization were noted in 113 of 149 in the BGC group and 133 of 189 in the non-BGC group according to Nguyen et al.2 However, the events were presented as 112 of 149 in the BGC group and 135 of 189 in the non-BGC group.1 Accordingly, the forest plot can be changed as in Fig. 1 below. Mechanical thrombectomy using BGC exhibited significantly higher successful recanalizations than did non-BGC use (OR, 1.710; 95% CI: 1.099-2.662). Second, there was no specific explanation for the publication bias of Fig. 4 in the result section.1 Although the authors reported a p value of 0.49 using Egger’s regression, we are not sure what publication bias meant to represent, successful recanalization or clinical outcome or other variables.
In this letter, we made a funnel plot for successful recanalization based on the revised number of events we h...
TO THE EDITOR: We read with interest the recent paper by Boned and colleagues.1 The authors conclude that “CT perfusion may overestimate final infarct core, especially in the early time window. Selecting patients for reperfusion therapies based on the CTP mismatch concept may deny treatment to patients who might still benefit from reperfusion”. We completely agree with this consideration, mainly when, as in this article, the core volume is assessed according to the classical CT perfusion (CTP) mismatch mean transit time (MTT)/cerebral blood volume (CBV)2 by measuring the lesion on CBV maps generated with a one-phase CT perfusion (CTP) acquisition protocol. In fact, it is well-known that a short CTP scan duration often produces a truncation of the perfusion curves resulting in an overestimation of CBV lesion that can frequently reverse.3 In addition, it has recently been demonstrated that relative cerebral blood flow (CBF) < 30% and time to peak of the residual function (Tmax) > 6 seconds is more reliable than CBV < 2.0 ml/100gr and relative MTT > 145% in identifying infarct core and ischemic penumbra at admission, respectively.4,5 As a consequence, the new CTP mismatch model Tmax/CBF was successfully used to include acute ischemic stroke (AIS) patients in the last trials showing the efficacy of endovascular treatment.6-9 We recently treated with combined intravenous thrombolysis and with mechanical thrombectomy patients imaged within 1.5 hour from symptom onset...
Show MoreWe read with interest the meta-analysis conducted by our colleague Dr Waleed Brinjikji (1). In the text (section "Limitations", he stated: "Data from the Interest of Direct Aspiration First Pass Technique (ADAPT) for Thrombectomy Revascularization of Large Vessel Occlusion in Acute Ischemic Stroke (ASTER) trial suggest that there were no statistically significant differences in revascularization rates when performing the ADAPT technique compared with using a stent retriever. However, it is unclear at this time whether BGCs were used in this trial."
Nevertheless in our publication of the ASTER trial results (2), we clearly stated in the Results section that a balloon-guide catheter was used to allow proximal flow arrest during stent retriever removal in 92% of patients treated with the stent retriever technique.
1. Brinjikji W, Starke RM, Murad MH, et al. Impact of balloon guide catheter on technical and clinical outcomes: a systematic review and meta-analysis. J Neurointerv Surg 2018;10:335–339.
2. Lapergue B, Blanc R, Gory B, et al. JAMA. 2017;318:443-452.
We read with interest the editorial by Darsaut and colleagues entitled, “PHASES and the natural history of unruptured aneurysms: science or pseudoscience?”[1]. Beginning with references to Aristotle and Pliny the Elder (always impressive), the authors launch a critique of studies of the natural history of unruptured aneurysms. With attention to ISUIA and the PHASES system, the contributors from Quebec call attention to limitations in both prospective and retrospective studies of the risk of rupture and associated risk factors for rupture of intracranial aneurysms. In their view, these imperfect studies are so deeply flawed that they are essentially useless as tools to inform decision-making with patients with unruptured intracranial aneurysms. Ending with the umpteenth call for a randomized trial, the authors create the impression that, for all patients with all kinds, sizes and locations of intracranial aneurysms, clinicians are powerless to use data from the available studies, condensed in the PHASES Score, to guide decision-making.
The PHASES score, developed from a pooled analysis of six prospective cohort studies of patients with unruptured intracranial aneurysms, was designed to use existing natural history data (limited though that may be), to provide some estimate of future rupture risk and to aid in identifying risk factors for rupture that may push clinician and patient past the treatment threshold. Several lines of evidence support the use of PHASES...
Show MoreWe appreciate the interest shown by Drs. Yao and You (1) in our paper (2) and find it our pleasure to address their concerns.
The first point raised by Drs. Yao and You is that our search strategy missed two articles, namely those of Mortimer et al (2015) (3) and Morgan et al (1996) (4). We would like to reassure Drs. Yao and You that we did screen these articles, and decided against including them in our meta-analysis based on our inclusion criteria. The article by Mortimer et al (2015) (3) describes a patient population where balloon angioplasty, verapamil, and papaverine infusions were used separately or in various combinations. They did not break down their results by the specific intra-arterial vasodilator (IAD) used, and therefore we decided not to include this information. The paper by Morgan et al (1996) (4) describes a patient population which overlapped with that described by the same group in another paper, Morgan et al (2000) (5). We had personally communicated with the authors in 2016 regarding the multiple papers from this group, such as Little et al (1994) (6) and Morgan et al (2000)
(5) that described papaverine infusions for vasospasm. We found out that there were overlaps in these study populations, and that the cohort in the 2000 paper(5) was the most complete. Therefore, only this paper was included in our meta-analysis, while the earlier ones were excluded.
The second suggestion by Drs. Yao and You was to perform a regression ana...
Show MoreWith great interest, we read the article of Venkatraman et al.[1] published in the Journal of NeuroInterventional Surgery recently. They presented a comprehensive picture depicting the effect of intra-arterial vasodilators (IADs) on the vasospasm following aneurysmal subarachnoid hemorrhage. But we were concerned with several questions weakening the reliability and generalization of the meta-analysis.
Show MoreFirstly , though the detailed including criteria and searching strategy were provided in their meta-analysis, at least two eligible studies2,3 were missed which conformed to their including criteria and unfulfilled the excluding criteria. Two cohort studies of Morgan [2] and Mortimer [3] reported the effects of IADs on vasospasm with documentation of interested events, which should be included in Venkatraman’s analysis. Whether addition of these two studies could change the overall effect of IADs was unclear, but including any eligible study was in accordance with PRISMA principle.
Secondly, owing to the large number of included studies, the heterogeneity was substantial. Venkatraman et al.[1] conducted subgroup and sensitivity analyses, in which the heterogeneity remained significant (most values of I2 greater than 50%). It was rationale to turn to regression analyses in order to find and solve the heterogeneity.
Besides, this article included studies combining IADs with balloon angioplasty, which might overestimate effectiveness of IADs. IADs w...
We read with great interest the article of Haussen et al. 1 outlining the problem of identifying patients with minor stroke symptoms (low NIHSS) despite proximal vessel occlusion who should undergo thrombectomy. Intension-to-treat analysis showed significantly higher reduction of stroke severity in the primary thrombectomy group compared to the medical group. But more interestingly, per-protocol analysis revealed a high propo...
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