We thank the respondents for providing their case experience and allowing further discussion of this important topic. We would first like to draw attention to specific points in the described case, before discussing some of the more general issues raised.
The respondents report one of many scenarios in which it may be undesirable to use dual antiplatelet therapy in the elective treatment of intracranial aneurysms with flow diverters. In this case, a 47-year-old woman with an 11 mm left ophthalmic aneurysm harbours a significant aspirin allergy. A single Pipeline Shield device under cover of ticagrelor was used to treat the aneurysm. The patient was well at discharge on postoperative day three but then developed symptomatic stent thrombosis on day 6. We draw attention to three points:
1) The respondents state that the stent achieved “perfect wall apposition improved with intra-stent balloon angioplasty.” Setting aside the impossibility of improving “perfect wall apposition” with angioplasty, this does allude to the increasingly understood importance of flow diverter wall apposition. [1] However, digital subtraction angiography assess stent apposition poorly. [1] The use of angioplasty suggests that there may have been some initial concern. Moreover, angioplasty itself may contribute to thrombosis if it promotes activation of the extrinsic clotting pathway by disrupting the endothelial layer. The phosphocholine “Shield” layer reduces thrombosis and platelet...
We thank the respondents for providing their case experience and allowing further discussion of this important topic. We would first like to draw attention to specific points in the described case, before discussing some of the more general issues raised.
The respondents report one of many scenarios in which it may be undesirable to use dual antiplatelet therapy in the elective treatment of intracranial aneurysms with flow diverters. In this case, a 47-year-old woman with an 11 mm left ophthalmic aneurysm harbours a significant aspirin allergy. A single Pipeline Shield device under cover of ticagrelor was used to treat the aneurysm. The patient was well at discharge on postoperative day three but then developed symptomatic stent thrombosis on day 6. We draw attention to three points:
1) The respondents state that the stent achieved “perfect wall apposition improved with intra-stent balloon angioplasty.” Setting aside the impossibility of improving “perfect wall apposition” with angioplasty, this does allude to the increasingly understood importance of flow diverter wall apposition. [1] However, digital subtraction angiography assess stent apposition poorly. [1] The use of angioplasty suggests that there may have been some initial concern. Moreover, angioplasty itself may contribute to thrombosis if it promotes activation of the extrinsic clotting pathway by disrupting the endothelial layer. The phosphocholine “Shield” layer reduces thrombosis and platelet aggregation via retarding activation of clotting factor XII at the stent surface(intrinsic pathway). It will exert no effect on the extrinsic pathway should it be activated.
2) The respondents do not mention if platelet response to ticagrelor was tested. This is not a criticism, as it is common to use new generation P2Y12 antagonists without testing their efficacy. However, it is also essential to understand ticagrelor resistance is reported in up to 3% of the population. [2] More recently we have experienced stent occlusions using the aspirin only technique in patients who were subsequently found to be aspirin non-responders. Given the loss of redundancy inherent in a single antiplatelet therapy (SAPT) technique, anti-platelet response testing should be reconsidered.
3) The timing of the symptomatic stent occlusion is noteworthy as it occurred three days post-discharge from hospital. This is somewhat unusual, as typically SAPT stent occlusions occur more acutely. Ticagerol’s shorter half-life means its effect will be subtherapeutic if discontinued for three days. Therefore, given the suspicious timing of the patient's stent occlusion, issues with patient compliance should be considered.
The use of the Pipeline Shield with aspirin only is a technique reserved for extreme circumstances. In aneurysmal SAH patients who cannot be treated successfully without the use of a stent and in whom antiplatelet therapy is undesirable or contraindicated, this technique may be appropriate. This has been stated in the original manuscript and is apparent in the description of the aneurysms treated. Our study reported an asymptomatic thromboembolic complication rate of 14.3% and a symptomatic rate of 7.1%. [3] Given the complex and extremely challenging nature of these cases, a symptomatic thromboembolic complication rate of 7.1% may be acceptable. The respondents point out that the combined rate is 21.4%. Any complications are too many, however, bear in mind that the thromboembolic complication rate in CLARITY was 12.5%. [4] Given the latter patient population underwent routine aneurysm coiling and the former represents patients without conventional treatment options this difference seems acceptable. Moreover, the symptomatic thromboembolic complication rate in the SAPT study is not very different from that reported in either ASPIRe or IntrePED. [5,6]
We believe that the addition of the phosphocholine "Shield" surface modification may allow greater flexibility in the use of antiplatelet therapy. It is increasingly clear that antiplatelet therapy is central to complications with flow diverting stents. Recent meta-analysis demonstrates that a hypo-response to DAPT increases the risk of thromboembolic complications and that a hyper-response increases the risk of haemorrhagic complications. [7] In the setting of acute aneurysm rupture, antiplatelet therapy is even more critical. The use of DAPT in such patients has been shown to increase the risks of haemorrhagic complications dramatically. [8] Therefore, any technology that may reduce our reliance on antiplatelet therapy should be fully explored.
The use of SAPT in complex ruptured aneurysms has nuanced advantages that may not be apparent to all readers. Many operators choose to delay treatment of ruptured aneurysms requiring a flow diverter to avoid dual antiplatelet therapy (DAPT) acutely. The mean time from subarachnoid haemorrhage (SAH) to aneurysm treatment in our study was one day. In comparison to 7 days in the meta-analysis reported by Cagnazzo et al. [9] This is particularly important to bear in mind when comparing retrospective studies as patients who re-ruptured before treatment will be excluded from analysis, however, undoubtedly represent treatment failure. This point is highlighted in a recent report by ten Brick and colleagues. [10] In this study, 44 patients with aneurysmal subarachnoid haemorrhage were treated with flow diverting stents on DAPT in five European centres. A range of flow diverters were used. However, none had the "Shield" surface modification. Aneurysm and patients characteristics were similar to the SAPT series we reported. Aneurysms were treated acutely (mean of three days post-SAH), although not as early as in the SAPT study. [3] Procedure-related complications occurred in 44%. Permanent neurological deficit due to procedure-related complications occurred in 27%. Perhaps of most interest to this discussion, post-procedure intracranial bleeding occurred in 22.7% including five aneurysm re-bleeds, two intraparenchymal haemorrhages not related to ventriculostomy, two ventricular shunt-related haemorrhages and one extra-axial haemorrhage. With extracranial haemorrhagic complications reported in another 9.1%. [10] In the SAPT series, two aneurysm re-bleeds occurred with one patient making a full recovery. The other patient, who was already a poor WFNS grade SAH never regained consciousness from the initial ictus. Both patients were being treated with postoperative heparin infusion at the time of aneurysm re-rupture, a practice which was subsequently abandoned as described in the original manuscript. In spite of similar patient and aneurysm characteristics, the DAPT case series reported good clinical outcomes in 45.5% compared to 64.3% in the SAPT series. Procedure-related mortality occurred in 11.4% and 7.1% of the DAPT and SAPT series, respectively.
Finally, it is essential to clarify the use of the term single antiplatelet therapy (SAPT). We are forced to take considerable responsibility for any misuse of this term. One should not consider the use of only one agent as the goal of this work. Instead, the goal is to offer patients with complex ruptured aneurysms, treatment using flow diverting (or other) stents with as little suppression of platelet function as is possible to avoid thromboembolic complications. The term "single antiplatelet therapy" has begun to appear in the literature, regarding the use of agents such as ticagrelor and prasugrel. Such terminology is literally correct; however, it misses the real goal of this work. As compared to P2Y12 antagonists, aspirin has a much less pronounced effect on platelet function and naturally, less haemorrhagic complication risk. [11] In most patients, agents such as ticagrelor and prasugrel likely suppress platelet function to such a degree that they make the addition of aspirin mostly redundant. [12,13]
We agree that further investigation of this technique is required, as stated in the original article. However, we think a randomised control trial would be inappropriate at this stage. It is somewhat facile to call for a randomised control trial to solve all medical dilemmas. It is safe to say that no treatment option is established for patients harbouring such complex ruptured aneurysms and therefore deciding on a control group would be somewhat arbitrary.
Furthermore, it is likely to be challenging to detect a significant difference in clinical outcomes given the uncertain prognosis of such patients independent of how their aneurysms are secured. Therefore, the number of patients that would need to be randomised likely exceeds 1000. We have elected to take a different approach and will study the Pipeline Shield SAPT technique in a multicentre, single-arm, prospective study. We hope that the first patients will be enrolled before this letter is published. The study will begin in Australia; however, it is planned to expand to other countries, and we encourage experienced and skilled centres such as yours to be a part of this investigation.
Thank you once again for an engaging discussion. Warm regards,
Nathan Manning
References:
1 Rouchaud A, Ramana C, Brinjikji W, et al. Wall Apposition Is a Key Factor for Aneurysm Occlusion after Flow Diversion: A Histologic Evaluation in 41 Rabbits. Am J Neuroradiol 2016;37:2087–91. doi:10.3174/ajnr.a4848
2 Warlo EM, Arnesen H, Seljeflot I. A brief review on resistance to P2Y12 receptor antagonism in coronary artery disease. Thrombosis J 2019;17:11. doi:10.1186/s12959-019-0197-5
3 Manning NW, Cheung A, Phillips TJ, et al. Pipeline shield with single antiplatelet therapy in aneurysmal subarachnoid haemorrhage: multicentre experience. Journal of neurointerventional surgery 2019;11:694–8. doi:10.1136/neurintsurg-2018-014363
4 Pierot L, Cognard C, Anxionnat R, et al. Ruptured intracranial aneurysms: factors affecting the rate and outcome of endovascular treatment complications in a series of 782 patients (CLARITY study). Radiology 2010;256:916–23. doi:10.1148/radiol.10092209
5 Kallmes DF, Brinjikji W, Boccardi E, et al. Aneurysm Study of Pipeline in an Observational Registry (ASPIRe). Interventional Neurology 2016;5:89–99. doi:10.1159/000446503
6 Kallmes D, Hanel R, Lopes D, et al. International retrospective study of the pipeline embolization device: a multicenter aneurysm treatment study. American Journal of Neuroradiology 2015;36:108–15. doi:10.3174/ajnr.a4111
7 Ajadi E, Kabir S, Cook A, et al. Predictive value of platelet reactivity unit (PRU) value for thrombotic and hemorrhagic events during flow diversion procedures: a meta-analysis. J Neurointerv Surg 2019;11:1123. doi:10.1136/neurintsurg-2019-014765
8 Hudson JS, Prout BS, Nagahama Y, et al. External Ventricular Drain and Hemorrhage in Aneurysmal Subarachnoid Hemorrhage Patients on Dual Antiplatelet Therapy: A Retrospective Cohort Study. Neurosurgery Published Online First: 2018. doi:10.1093/neuros/nyy127
9 Cagnazzo F, di Carlo D, Cappucci M, et al. Acutely Ruptured Intracranial Aneurysms Treated with Flow-Diverter Stents: A Systematic Review and Meta-Analysis. American Journal of Neuroradiology 2018;39:1669–75. doi:10.3174/ajnr.a5730
10 ten Brinck MF, Jäger M, de Vries J, et al. Flow diversion treatment for acutely ruptured aneurysms. J Neurointerv Surg 2019;:neurintsurg-2019-015077. doi:10.1136/neurintsurg-2019-015077
11 Gresele P. Antiplatelet agents in clinical practice and their haemorrhagic risk. Blood Transfus Trasfusione Del Sangue 2013;11:349–56. doi:10.2450/2013.0248-12
12 KIRKBY N, LEADER P, CHAN M, et al. Antiplatelet effects of aspirin vary with level of P2Y12 receptor blockade supplied by either ticagrelor or prasugrel. J Thromb Haemost 2011;9:2103–5. doi:10.1111/j.1538-7836.2011.04453.x
13 Warner TD, Nylander S, Whatling C. Anti‐platelet therapy: cyclo‐oxygenase inhibition and the use of aspirin with particular regard to dual anti‐platelet therapy. Brit J Clin Pharmaco 2011;72:619–33. doi:10.1111/j.1365-2125.2011.03943.x
Thank you for your technical considerations regarding stent in stent placement without hooking the first stent.
Use of 3 D Roadmap may be helpful. Moreover, following passage of the microwire, reconstructions of a second flat panel angioCT with the microwire in place clearly outlines the relationship between the microwire and the struts of the first stent, especially if reconstructions perpendicular to the orientati...
Thank you for your technical considerations regarding stent in stent placement without hooking the first stent.
Use of 3 D Roadmap may be helpful. Moreover, following passage of the microwire, reconstructions of a second flat panel angioCT with the microwire in place clearly outlines the relationship between the microwire and the struts of the first stent, especially if reconstructions perpendicular to the orientation of the first stent are performed. This may avoid the passage of the stent with a DAC (Distal Access Catheter) which may demage or displace the first stent, especially at it's proximal end.
Using this technique, even passage through a deformed and fragmented stent can be performed, and the location of the microwire within the central axis of the first stent can be confirmed before introduction of the second stent or flow diverter.
Mordasini P, Al-Senani F, Gralla J, Do D, Schroth G: The use of flat Panel angioCT (DynaCT) for Navigation through a deformed and fractured carotid stent. Neuroradiology 52; 2010:629-632.
Prof. Gerhard Schroth Neurologist and Radiologist gerhard.schroth@insel.ch University of Bern Senior Consultant of the Institute for Diagnostic and Interventional Neuroradiology
I read with interest the article "Onyx extrusion through the scalp
after embolization of dural arteriovenous fistula" by SIngla et al. The
objective of the article is mainly to reinforce in our pre-treatment
discussions the need to include as much as possible the outcomes arising
from the use of Onyx that include, but are not exclusively related to,
micro catheter retention or rupture, unintended ves...
I read with interest the article "Onyx extrusion through the scalp
after embolization of dural arteriovenous fistula" by SIngla et al. The
objective of the article is mainly to reinforce in our pre-treatment
discussions the need to include as much as possible the outcomes arising
from the use of Onyx that include, but are not exclusively related to,
micro catheter retention or rupture, unintended vessel occlusion and the
possibility of stroke.
The use of the occipital artery is a valid means of occluding
fistulas of the transverse sinus and on occasion the torcula however there
is the risk of skin necrosis especially if reflux is obtained to the
degree seen here in this case, filling the contralateral occipital artery.
We have used the middle meningeal artery to occlude such superior
sagittal sinus, other transverse sinus and higher grade dural fistulas
with detachable tip micro catheters such as Apollo (eV3) and Sonic (BALT)
and dual lumen remodelling balloons (Sceptre C, Microvention)1.
Perhaps use of the middle meningeal artery feeders would have pre-
empted surgery and completed the treatment endovascularly as well as
avoiding possible skin necrosis from use of the occipital arteries and
potential skin extrusion of the embolic agent. We understand that a
complete endovascular cure may not be achievable without venous balloon
remodelling using the Copernic balloon ( BALT) but the same
clinical/angiographic result can be obtained with careful monitoring of
the sinus lumen on an anteroposterior view. It may be that both middle
meningeal arteries arose from the ophthalmic arteries, thus precluding
their use. This would be very unusual however.
Thus in summary, use of the middle meningeal arteries in this case
may have precluded the surgery and having to expose the occipital artery
territories and scalp to the liquid embolic agent. Thus possible skin
necrosis and the observed material extrusion could be avoided.
Reference:
1. Preliminary experience with the liquid embolic material agent PHIL
(Precipitating Hydrophobic Injectable Liquid) in treating cranial and
spinal dural arteriovenous fistulas: technical note
Joe J Leyon, Swarupsinh Chavda, Allan Thomas and Saleh Lamin
J NeuroIntervent Surg published online May 20, 2015
It is with great interest that we read the study of Alawieh et al(1), in which they developed a machine learning algorithm, called ‘SPOT’, to select stroke patients older than 80 years for endovascular therapy (EVT). Prediction modeling to optimize patient selection for EVT is an emerging topic of interest and we agree that predicting individual patient outcomes is increasingly important for decision making in medicine. However, we were surprised by the strong conclusions that were drawn by the authors, considering some serious limitations of the study.
First, the size of the training set is insufficient to develop a complex model with twelve predictor variables and many correlations. Only 22 patients had a good functional outcome, which means that the number of events per tested predictor variable is less than two. For the development of a reliable model, a sample size of at least ten events per variable is needed to minimize the risk of overfitting(2, 3). It has been suggested that even far more events per variable are needed to achieve stable predictions with machine learning techniques(4). Especially complex models developed on small sample sizes have a high risk of overfitting, resulting in unstable predictions and too optimistic model performance measures. The reported AUC of 0.92 is therefore very likely to be an overestimation.
Second, the SPOT algorithm provides a treatment advice based on the predicted outcome after treatment, without providing the...
It is with great interest that we read the study of Alawieh et al(1), in which they developed a machine learning algorithm, called ‘SPOT’, to select stroke patients older than 80 years for endovascular therapy (EVT). Prediction modeling to optimize patient selection for EVT is an emerging topic of interest and we agree that predicting individual patient outcomes is increasingly important for decision making in medicine. However, we were surprised by the strong conclusions that were drawn by the authors, considering some serious limitations of the study.
First, the size of the training set is insufficient to develop a complex model with twelve predictor variables and many correlations. Only 22 patients had a good functional outcome, which means that the number of events per tested predictor variable is less than two. For the development of a reliable model, a sample size of at least ten events per variable is needed to minimize the risk of overfitting(2, 3). It has been suggested that even far more events per variable are needed to achieve stable predictions with machine learning techniques(4). Especially complex models developed on small sample sizes have a high risk of overfitting, resulting in unstable predictions and too optimistic model performance measures. The reported AUC of 0.92 is therefore very likely to be an overestimation.
Second, the SPOT algorithm provides a treatment advice based on the predicted outcome after treatment, without providing the absolute probability of good functional outcome or the treatment benefit. Rational treatment decisions should be based on expected outcome with treatment compared to the expected outcome without treatment. A low likelihood of good outcome does not imply absence of treatment benefit. Besides that, many octogenarians might not be able to achieve complete recovery to functional independence, but an improvement from an mRS score of 4-5 to a score of 3 as a result of EVT can still be very relevant in clinical practice, and such outcome is not covered by the SPOT algorithm.
Well-developed prediction models may guide us in the selection of patients that benefit from treatment, but external validation in a large validation set is always needed before these models are implemented in everyday clinical care. The SPOT algorithm does not yet fulfill the minimum requirements for a well-developed and validated decision support tool. This means that an effective treatment may be withheld from patients who could benefit from it. Therefore, the SPOT algorithm should not yet be implemented in clinical care.
References
1. Alawieh A, Zaraket F, Alawieh MB, Chatterjee AR, Spiotta A. Using machine learning to optimize selection of elderly patients for endovascular thrombectomy. J Neurointerv Surg. 2019.
2. Peduzzi P, Concato J, Kemper E, Holford TR, Feinstein AR. A simulation study of the number of events per variable in logistic regression analysis. J Clin Epidemiol. 1996;49(12):1373-9.
3. Harrell FE, Jr., Lee KL, Mark DB. Multivariable prognostic models: issues in developing models, evaluating assumptions and adequacy, and measuring and reducing errors. Stat Med. 1996;15(4):361-87.
4. van der Ploeg T, Austin PC, Steyerberg EW. Modern modelling techniques are data hungry: a simulation study for predicting dichotomous endpoints. BMC Med Res Methodol. 2014;14:137.
We read with interest the response to our manuscript on using machine learning to optimize elderly patient selection for endovascular thrombectomy (1). We acknowledge here, as the author reports, the limitation of SPOT being based on single center data, and the need for multicenter prospective validation of SPOT as next step in development. The author raises additional technical concerns that we do not necessarily view as applicable to this study.
First, we would like to stress the general limitations of artificial intelligence based techniques such as the overfitting and the data specific local optima problems. However, the specific comments brought by the author are not applicable in our case. First, studies on the number of events per predictor are applicable for logistic regressions (LRs) which is not used in the SPOT algorithm. In fact, our results show poor LR performance which is consistent with the rule of thumb of 1 to 10 referred to by the author. Hence, while serving as a good guidance for LR, the rule is not binding and more importantly it does not guarantee the generalization of the learned model. To further illustrate, classification models using convolutional neural networks have millions of parameters and are trained with datasets that, in most cases, do not have millions of samples in each group. However, these models have acceptable generalization capabilities and are tested using the data-split method. In SPOT, the model at its core is a regressi...
We read with interest the response to our manuscript on using machine learning to optimize elderly patient selection for endovascular thrombectomy (1). We acknowledge here, as the author reports, the limitation of SPOT being based on single center data, and the need for multicenter prospective validation of SPOT as next step in development. The author raises additional technical concerns that we do not necessarily view as applicable to this study.
First, we would like to stress the general limitations of artificial intelligence based techniques such as the overfitting and the data specific local optima problems. However, the specific comments brought by the author are not applicable in our case. First, studies on the number of events per predictor are applicable for logistic regressions (LRs) which is not used in the SPOT algorithm. In fact, our results show poor LR performance which is consistent with the rule of thumb of 1 to 10 referred to by the author. Hence, while serving as a good guidance for LR, the rule is not binding and more importantly it does not guarantee the generalization of the learned model. To further illustrate, classification models using convolutional neural networks have millions of parameters and are trained with datasets that, in most cases, do not have millions of samples in each group. However, these models have acceptable generalization capabilities and are tested using the data-split method. In SPOT, the model at its core is a regression model with continuous output. More importantly, while the overfitting concern is a valid one with the high area under a curve, SPOT was tested in an adequate fashion using data-splitting, a well-accepted validation scheme to test the generalization capability of the model, and thus detect overfitting. In fact, studies discussing events per variable rule for logistic regression use data-splitting as one of the validation method (2). The approach used for testing SPOT using a prospective data not part of the training is the most stringent approach to test a model. In fact, state of the art machine learning model evaluations use the data-splitting technique, and consider the performance of the testing data as the golden metric to judge upon the model’s generalization and over-fitting (3,4).
While we agree with the fact that machine learning are data hungry, the size of the dataset is highly dependent on the problem at hand. For example, in sparse regression models, the number of samples in the training dataset can be orders of magnitude smaller than that of the parameters. However, sparse regression models joined with proper training techniques are able to generalize to unseen data (5). Again, this ability is tested using the data-split method which was used to test SPOT.
Further, we emphasize that although SPOT returns a continuous output of mRS scores, the tool will specifically report grouped outcomes into mRS 0-2 and mRS 3-6. The decision to choose this dichotomy of outcomes was to be consistent with clinical trials that predominantly report functional independence as outcome measure to guide interventions even when elderly patients were included. In response to the concern about returning probability for outcomes, and as stated in the manuscript, when SPOT returns poor outcome prediction, its negative predictive value was 95.2% which represents the probability for a patient that screened negative to have a poor outcome and this probability is reported in the text. In the current form, SPOT does not return a probability for every mRS score.
Finally, while we agree that multicenter data is needed to additionally validate SPOT as a tool as stated in the manuscript, the current version of SPOT does meet technical requirements for a validated tool. We do stress again that “SPOT is designed to aid clinical decision of whether to undergo ET in elderly patients” (1), and not a stand-alone tool.
References
1. Alawieh A, Zaraket F, Alawieh MB, Chatterjee AR, Spiotta A. Using machine learning to optimize selection of elderly patients for endovascular thrombectomy. J Neurointerv Surg. 2019.
2. Harrell FE, Jr., Lee KL, Mark DB. Multivariable prognostic models: issues in developing models, evaluating assumptions and adequacy, and measuring and reducing errors. Stat Med. 1996;15(4):361-87.
3. Kohavi, Ron. "A study of cross-validation and bootstrap for accuracy estimation and model selection." Ijcai. Vol. 14. No. 2. 1995.
4. Arlot, Sylvain, and Alain Celisse. "A survey of cross-validation procedures for model selection." Statistics surveys4 (2010): 40-79.
5. Donoho, David Leigh, et al. Sparse solution of underdetermined linear equations by stagewise orthogonal matching pursuit. Department of Statistics, Stanford University, 2006.
Congratulations to Annika Keuler et al¹ on their experience with the wireless microcatheter technique preventing vessel perforations in endovascular thrombectomy. Based on their results, the authors conclude that in most cases of mechanical recanalization, the clot can be passed more safely with a wireless microcatheter. In our daily work, we also find the wireless microcatheter technique seems to reduce subarachnoid hyperdensity resulting from vessel perforations. However it seems difficult to confirm this correlation; the details of which will be discussed as follows. After reading and analyzing the article carefully, we have some opinions about the study which we would like to communicate with the authors because the conclusions of the paper directly relate to our clinical experience.
In the article, two radiological manifestations are defined as vessel perforations——contrast extravasation during angiography and angiographically occult ipsilateral circumscribed subarachnoid contrast extravasation which is identified by post-interventional CT scans. As confirmed by previous studies2-3, we agree with the authors on using immediate post-interventional CT examination to identify the subarachnoid hyperdensity due to intraoperative contrast extravasation. Based on their results, post-thrombectomy subarachnoid hyperdensity was observed on CT scans in 22 patients, in 18 of whom, the clot was passed using a microwire, and in the other four, using a wireless microcathete...
Congratulations to Annika Keuler et al¹ on their experience with the wireless microcatheter technique preventing vessel perforations in endovascular thrombectomy. Based on their results, the authors conclude that in most cases of mechanical recanalization, the clot can be passed more safely with a wireless microcatheter. In our daily work, we also find the wireless microcatheter technique seems to reduce subarachnoid hyperdensity resulting from vessel perforations. However it seems difficult to confirm this correlation; the details of which will be discussed as follows. After reading and analyzing the article carefully, we have some opinions about the study which we would like to communicate with the authors because the conclusions of the paper directly relate to our clinical experience.
In the article, two radiological manifestations are defined as vessel perforations——contrast extravasation during angiography and angiographically occult ipsilateral circumscribed subarachnoid contrast extravasation which is identified by post-interventional CT scans. As confirmed by previous studies2-3, we agree with the authors on using immediate post-interventional CT examination to identify the subarachnoid hyperdensity due to intraoperative contrast extravasation. Based on their results, post-thrombectomy subarachnoid hyperdensity was observed on CT scans in 22 patients, in 18 of whom, the clot was passed using a microwire, and in the other four, using a wireless microcatheter. The authors concluded that the complication rate for post-thrombectomy hyperdensity was significantly higher when a microwire was used to pass the clot. However, Omid Nikoubashman et al² report that post-interventional subarachnoid hyperdensities are associated with a long interval between clinical onset and recanalization, a long procedure time, and a high number of recanalization attempts. Perry P Ng et al ³ also mention that an increased number of stent retriever passes, distal device positioning, and presence of severe vasospasm were associated with post-thrombectomy subarachnoid hyperdensity. Additionaly, the interventional neuroradiologists used a microwire to pass the clot when first-pass microcatheter passage was not successful. There is confounding bias in this practice itself——It could be more difficult to pass the clot and need more stent retriever attempts in the microwire use group.
To sum up, hyperdensity on immediate post-thrombectomy CT scans, a manifestation of vessel perforation, is associated with many factors. The conclusion that the wireless technique can reduce post-thrombectomy hyperdensity would be more convincing if the authors ruled out the association between subarachnoid contrast extravasation and potential risk factors.
Yuan Ma, Pei-Cheng Li, Long Chen
Department of Interventional Radiology, The First Affiliated Hospital of Soochow University, Suzhou, China.
Correspondence to Dr. Long Chen, Department of Interventional Radiology, The First Affiliated Hospital of Soochow University, 188 Shizi Street,215006 Suzhou, China;lchen76@163.com
References:
1 Keulers A, Nikoubashman O, Mpotsaris A, et al. Preventing vessel perforations in endovascular thrombectomy: feasibility and safety of passing the clot with a microcatheter without microwire: the wireless microcatheter technique. J Neurointerv Surg 2018: 2018-14267.
2 Nikoubashman O, Reich A, Pjontek R, et al. Postinterventional subarachnoid haemorrhage after endovascular stroke treatment with stent retrievers. Neuroradiology 2014;56: 1087-1096.
3 Ng PP, Larson TC, Nichols CW, et al. Intraprocedural predictors of post-stent retriever thrombectomy subarachnoid hemorrhage in middle cerebral artery stroke. J Neurointerv Surg 2018;11: 127-132.
We read with interest the article by Soize et al. “Can early neurological improvement after mechanical thrombectomy be used as a surrogate for final stroke outcome?”[1] Based on their results, the authors concluded that early neurological improvement (ENI) 24 hours after thrombectomy is a straightforward surrogate of long-term outcome. However, all patients in this study were treated with conscious sedation (CS), and not general anesthesia (GA). The residual effects of GA may mask ENI and limit its utility as a surrogate for long-term outcome.[2]
We performed a similar analysis of patients enrolled in a prospective single-center registry. The ability of ENI to predict 3-month functional independence was assessed by the area under the receiver operating characteristic curve (AUC) and compared using the independent-samples Hanley test. Multivariable linear regression assessing the relationship between anesthetic technique and ENI was also performed. The analysis received ethics approval.
291 patients were treated with thrombectomy, with 261 (89.7%) procedures performed with GA, and 30 (10.3%) with CS. All patients were de-sedated and extubated more than 12 hours before 24-hour National Institutes of Health Stroke Scale assessment. 174 (59.8%) patients achieved 3-month functional independence. Baseline and procedural characteristics did not differ between GA and CS patients (all P>0.05). ENI demonstrated better prognostic ability in CS (AUC 0.91, 95% confiden...
We read with interest the article by Soize et al. “Can early neurological improvement after mechanical thrombectomy be used as a surrogate for final stroke outcome?”[1] Based on their results, the authors concluded that early neurological improvement (ENI) 24 hours after thrombectomy is a straightforward surrogate of long-term outcome. However, all patients in this study were treated with conscious sedation (CS), and not general anesthesia (GA). The residual effects of GA may mask ENI and limit its utility as a surrogate for long-term outcome.[2]
We performed a similar analysis of patients enrolled in a prospective single-center registry. The ability of ENI to predict 3-month functional independence was assessed by the area under the receiver operating characteristic curve (AUC) and compared using the independent-samples Hanley test. Multivariable linear regression assessing the relationship between anesthetic technique and ENI was also performed. The analysis received ethics approval.
291 patients were treated with thrombectomy, with 261 (89.7%) procedures performed with GA, and 30 (10.3%) with CS. All patients were de-sedated and extubated more than 12 hours before 24-hour National Institutes of Health Stroke Scale assessment. 174 (59.8%) patients achieved 3-month functional independence. Baseline and procedural characteristics did not differ between GA and CS patients (all P>0.05). ENI demonstrated better prognostic ability in CS (AUC 0.91, 95% confidence interval [CI], 0.80-1.00) than it did with GA treated patients (AUC 0.73, 95% CI, 0.67-0.80; P=0.008). Multivariable regression showed that GA was independently associated with attenuated ENI (P=0.03).
Our findings are in agreement with Soize et al, in that ENI does seem to predict long-term outcome in thrombectomy patients treated with CS, with comparable AUCs (0.91 and 0.93 respectively).[1] However, our results also suggest that ENI is worse at predicting long-term outcome following thrombectomy performed with GA. Furthermore, GA was independently associated with attenuated ENI, suggesting that GA might mask early neurologic recovery. These trends would appear to be in agreement with the SIESTA trial, which reported a greater likelihood of achieving 3-month functional independence in GA than CS patients, in the absence of significant differences in ENI.[3] Post-hoc analysis of SIESTA showed that propofol dose during thrombectomy was independently associated with reduced ENI.[2] The possible mechanisms for GA attenuating ENI may include the residual pharmacological effects of benzodiazepines, opioids, neuromuscular blockers, and intravenous or volatile anesthetic agents, or transient complications of endotracheal intubation such as ventilator-associated complications.[4]
[1] Soize S, Fabre G, Gawlitza M, et al. Can early neurological improvement after mechanical thrombectomy be used as a surrogate for final stroke outcome? J. Neurointerv. Surg. 2019;11(5):450-454.
[2] Schönenberger S, Uhlmann L, Ungerer M, et al. Association of Blood Pressure With Short- and Long-Term Functional Outcome After Stroke Thrombectomy: Post Hoc Analysis of the SIESTA Trial. Stroke. 2018;49:1451–1456.
[3] Schönenberger S, Uhlmann L, Hacke W, et al. Effect of Conscious Sedation vs General Anesthesia on Early Neurological Improvement Among Patients With Ischemic Stroke Undergoing Endovascular Thrombectomy: A Randomized Clinical Trial. JAMA. 2016;316:1986–1996.
[4] Sinclair RCF, Faleiro RJ. Delayed recovery of consciousness after anaesthesia. Continuing Education in Anaesthesia, Critical Care & Pain. 2006;6:114–118.
We would like to congratulate Nicholson et al. on their highly interesting work on the declining rate of SAH in the Irish population. This will certainly provide some very interesting points. Also in Germany there is - at least subjectively - the phenomenon of the declining rate of SAH. The authors can establish a clear correlation to the decline in the smoking rate. Now the question arises whether this is the only relevant correlation. In particular, it would certainly be necessary to investigate whether there has been an increased rate of detection of unruptered Aneurysma and an increasing rate of treatment of those during the study period and whether this may also have a relevant influence on the decrease in SAH.
We had an opportunity to read the article by Lakomkin et al regarding systematic literature review of LVO prevalence. Since one of our studies is part of this review we feel compelled to comment on the paper. We do appreciate the authors’ efforts in conducting this analysis which is important in understanding the burden of disease – but, with respect offer some criticisms. The major limitation of the paper which the authors recognize is the heterogeneity of the included studies. Unfortunately, this limitation is so critical that it yields unreliable information at best and misleading at worst.
The paper intends to study the prevalence of large vessel strokes. However, apart from a couple of population based studies in their review, the rest are a heterogenous mix describing an LVO rate from very selective cohorts of patients from single centers. Several are centered around validation of clinical scales for detecting LVOs. The key features of a population based study include a defined catchment population, access to a large part of that population and a reliable marker of disease. Without these a “prevalence” constitutes a report of a center’s experience of disease rate as it pertains to their patient intake. While still valuable it is not an estimation of the disease burden in the population that the center serves unless an overwhelming majority of that population comes to that center.
The authors determine an average rate of about 30% LVO amongst acute isch...
We had an opportunity to read the article by Lakomkin et al regarding systematic literature review of LVO prevalence. Since one of our studies is part of this review we feel compelled to comment on the paper. We do appreciate the authors’ efforts in conducting this analysis which is important in understanding the burden of disease – but, with respect offer some criticisms. The major limitation of the paper which the authors recognize is the heterogeneity of the included studies. Unfortunately, this limitation is so critical that it yields unreliable information at best and misleading at worst.
The paper intends to study the prevalence of large vessel strokes. However, apart from a couple of population based studies in their review, the rest are a heterogenous mix describing an LVO rate from very selective cohorts of patients from single centers. Several are centered around validation of clinical scales for detecting LVOs. The key features of a population based study include a defined catchment population, access to a large part of that population and a reliable marker of disease. Without these a “prevalence” constitutes a report of a center’s experience of disease rate as it pertains to their patient intake. While still valuable it is not an estimation of the disease burden in the population that the center serves unless an overwhelming majority of that population comes to that center.
The authors determine an average rate of about 30% LVO amongst acute ischemic stroke (AIS) patients based on their review. The critical factor here is the denominator, i.e. the number of AIS patients from which the LVO rate is derived. It can be misrepresentative to extrapolate disease rate to a larger denominator derived from a different methodology. For instance, the oft quoted denominator of about 700,000 ischemic strokes is based on population studies using very specific ICD discharge codes in well-defined populations. Examples include the GCNKSS and the BASIC projects. Unless a study uses the same discharge codes in its methodology for determining the AIS denominator it cannot transplant LVO percentages calculated from its selective cohort to the larger denominator and derive absolute numbers of disease. For instance, a 30% LVO rate in a cohort of patients assessed as having an ischemic stroke by the EMS is not the same as 30% LVO rate amongst all AIS based on specific ICD discharge codes. Using the percentage from one cohort and applying to a different denominator could yield inaccurate absolute numbers.
The study from our center that is included in this analysis was designed to capture the LVO incidence in a unique well defined population of which the vast majority (85%) was served by our hospital system based on each county data reported to the DHHR. Thus, similar to the studies used to derive the total AIS estimates (e.g. GCNKSS, BASIC) we had a defined population, had significant access to the population and used the same ICD discharge codes to determine the denominator as in those studies. We also used a reliable marker of LVO, i.e. CTA performed on every AIS patient as identified by these codes. In our first paper an LVO was defined as ICA-T, MCA and BA to restrict it predominantly to the occlusion sites considered as LVO in the major clinical trials. In our second paper, not included in this analysis, we separately determined an incidence of M2 occlusions and combined with ICA-T, M1, BA this yields a rate of 16% (95CI 14-17). In our population, this gives an incidence of 31 (95CI 26-35)/100,000 people/year. Our second paper also includes a chart showing the location of occluded sites for other vessels not considered as LVOs i.e. ACA, PICA, SCA, PCA etc.
The authors comment on our inclusion of TIA codes in the denominator. We did that because it had been part of previous population studies evaluating AIS incidences. TIA comprised at most 1% of our denominator and if we exclude these patients, the incidence of 16% LVO does not change by more than a percentage point. Another variable to consider in a single center report is that a tertiary level comprehensive center may get transfers of sicker stroke patients from referring hospitals which can further skew the denominator and hence the derived LVO rate.
In summary, it is important to differentiate between population studies and single center experiences – especially when compiling these in a systematic review. It is critical when extrapolating disease incidence from one center’s report to the national disease burden that the methodology of deriving the larger denominator is the same. Nonetheless we do appreciate this review and commend the authors on their efforts. This highlights the need for collaborative efforts to collect population data based on a uniform methodology. These efforts should include state and federal registers that collect health data based on specific disease codes. Such collective ventures can provide more realistic estimates of the LVO burden and help shape systems of care.
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).
We thank the respondents for providing their case experience and allowing further discussion of this important topic. We would first like to draw attention to specific points in the described case, before discussing some of the more general issues raised.
The respondents report one of many scenarios in which it may be undesirable to use dual antiplatelet therapy in the elective treatment of intracranial aneurysms with flow diverters. In this case, a 47-year-old woman with an 11 mm left ophthalmic aneurysm harbours a significant aspirin allergy. A single Pipeline Shield device under cover of ticagrelor was used to treat the aneurysm. The patient was well at discharge on postoperative day three but then developed symptomatic stent thrombosis on day 6. We draw attention to three points:
1) The respondents state that the stent achieved “perfect wall apposition improved with intra-stent balloon angioplasty.” Setting aside the impossibility of improving “perfect wall apposition” with angioplasty, this does allude to the increasingly understood importance of flow diverter wall apposition. [1] However, digital subtraction angiography assess stent apposition poorly. [1] The use of angioplasty suggests that there may have been some initial concern. Moreover, angioplasty itself may contribute to thrombosis if it promotes activation of the extrinsic clotting pathway by disrupting the endothelial layer. The phosphocholine “Shield” layer reduces thrombosis and platelet...
Show MoreThank you for your technical considerations regarding stent in stent placement without hooking the first stent.
Use of 3 D Roadmap may be helpful. Moreover, following passage of the microwire, reconstructions of a second flat panel angioCT with the microwire in place clearly outlines the relationship between the microwire and the struts of the first stent, especially if reconstructions perpendicular to the orientati...
Dear Sirs,
I read with interest the article "Onyx extrusion through the scalp after embolization of dural arteriovenous fistula" by SIngla et al. The objective of the article is mainly to reinforce in our pre-treatment discussions the need to include as much as possible the outcomes arising from the use of Onyx that include, but are not exclusively related to, micro catheter retention or rupture, unintended ves...
It is with great interest that we read the study of Alawieh et al(1), in which they developed a machine learning algorithm, called ‘SPOT’, to select stroke patients older than 80 years for endovascular therapy (EVT). Prediction modeling to optimize patient selection for EVT is an emerging topic of interest and we agree that predicting individual patient outcomes is increasingly important for decision making in medicine. However, we were surprised by the strong conclusions that were drawn by the authors, considering some serious limitations of the study.
First, the size of the training set is insufficient to develop a complex model with twelve predictor variables and many correlations. Only 22 patients had a good functional outcome, which means that the number of events per tested predictor variable is less than two. For the development of a reliable model, a sample size of at least ten events per variable is needed to minimize the risk of overfitting(2, 3). It has been suggested that even far more events per variable are needed to achieve stable predictions with machine learning techniques(4). Especially complex models developed on small sample sizes have a high risk of overfitting, resulting in unstable predictions and too optimistic model performance measures. The reported AUC of 0.92 is therefore very likely to be an overestimation.
Second, the SPOT algorithm provides a treatment advice based on the predicted outcome after treatment, without providing the...
Show MoreWe read with interest the response to our manuscript on using machine learning to optimize elderly patient selection for endovascular thrombectomy (1). We acknowledge here, as the author reports, the limitation of SPOT being based on single center data, and the need for multicenter prospective validation of SPOT as next step in development. The author raises additional technical concerns that we do not necessarily view as applicable to this study.
First, we would like to stress the general limitations of artificial intelligence based techniques such as the overfitting and the data specific local optima problems. However, the specific comments brought by the author are not applicable in our case. First, studies on the number of events per predictor are applicable for logistic regressions (LRs) which is not used in the SPOT algorithm. In fact, our results show poor LR performance which is consistent with the rule of thumb of 1 to 10 referred to by the author. Hence, while serving as a good guidance for LR, the rule is not binding and more importantly it does not guarantee the generalization of the learned model. To further illustrate, classification models using convolutional neural networks have millions of parameters and are trained with datasets that, in most cases, do not have millions of samples in each group. However, these models have acceptable generalization capabilities and are tested using the data-split method. In SPOT, the model at its core is a regressi...
Show MoreCongratulations to Annika Keuler et al¹ on their experience with the wireless microcatheter technique preventing vessel perforations in endovascular thrombectomy. Based on their results, the authors conclude that in most cases of mechanical recanalization, the clot can be passed more safely with a wireless microcatheter. In our daily work, we also find the wireless microcatheter technique seems to reduce subarachnoid hyperdensity resulting from vessel perforations. However it seems difficult to confirm this correlation; the details of which will be discussed as follows. After reading and analyzing the article carefully, we have some opinions about the study which we would like to communicate with the authors because the conclusions of the paper directly relate to our clinical experience.
Show MoreIn the article, two radiological manifestations are defined as vessel perforations——contrast extravasation during angiography and angiographically occult ipsilateral circumscribed subarachnoid contrast extravasation which is identified by post-interventional CT scans. As confirmed by previous studies2-3, we agree with the authors on using immediate post-interventional CT examination to identify the subarachnoid hyperdensity due to intraoperative contrast extravasation. Based on their results, post-thrombectomy subarachnoid hyperdensity was observed on CT scans in 22 patients, in 18 of whom, the clot was passed using a microwire, and in the other four, using a wireless microcathete...
We read with interest the article by Soize et al. “Can early neurological improvement after mechanical thrombectomy be used as a surrogate for final stroke outcome?”[1] Based on their results, the authors concluded that early neurological improvement (ENI) 24 hours after thrombectomy is a straightforward surrogate of long-term outcome. However, all patients in this study were treated with conscious sedation (CS), and not general anesthesia (GA). The residual effects of GA may mask ENI and limit its utility as a surrogate for long-term outcome.[2]
We performed a similar analysis of patients enrolled in a prospective single-center registry. The ability of ENI to predict 3-month functional independence was assessed by the area under the receiver operating characteristic curve (AUC) and compared using the independent-samples Hanley test. Multivariable linear regression assessing the relationship between anesthetic technique and ENI was also performed. The analysis received ethics approval.
291 patients were treated with thrombectomy, with 261 (89.7%) procedures performed with GA, and 30 (10.3%) with CS. All patients were de-sedated and extubated more than 12 hours before 24-hour National Institutes of Health Stroke Scale assessment. 174 (59.8%) patients achieved 3-month functional independence. Baseline and procedural characteristics did not differ between GA and CS patients (all P>0.05). ENI demonstrated better prognostic ability in CS (AUC 0.91, 95% confiden...
Show MoreWe would like to congratulate Nicholson et al. on their highly interesting work on the declining rate of SAH in the Irish population. This will certainly provide some very interesting points. Also in Germany there is - at least subjectively - the phenomenon of the declining rate of SAH. The authors can establish a clear correlation to the decline in the smoking rate. Now the question arises whether this is the only relevant correlation. In particular, it would certainly be necessary to investigate whether there has been an increased rate of detection of unruptered Aneurysma and an increasing rate of treatment of those during the study period and whether this may also have a relevant influence on the decrease in SAH.
We had an opportunity to read the article by Lakomkin et al regarding systematic literature review of LVO prevalence. Since one of our studies is part of this review we feel compelled to comment on the paper. We do appreciate the authors’ efforts in conducting this analysis which is important in understanding the burden of disease – but, with respect offer some criticisms. The major limitation of the paper which the authors recognize is the heterogeneity of the included studies. Unfortunately, this limitation is so critical that it yields unreliable information at best and misleading at worst.
The paper intends to study the prevalence of large vessel strokes. However, apart from a couple of population based studies in their review, the rest are a heterogenous mix describing an LVO rate from very selective cohorts of patients from single centers. Several are centered around validation of clinical scales for detecting LVOs. The key features of a population based study include a defined catchment population, access to a large part of that population and a reliable marker of disease. Without these a “prevalence” constitutes a report of a center’s experience of disease rate as it pertains to their patient intake. While still valuable it is not an estimation of the disease burden in the population that the center serves unless an overwhelming majority of that population comes to that center.
The authors determine an average rate of about 30% LVO amongst acute isch...
Show MoreDear 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...
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