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Abstract
Background Medium vessel occlusions (MeVOs) comprise a large proportion of all stroke events. We performed a multicenter study of MIVI Q catheters, a novel design that optimizes suction forces without an increase in lumen diameter, for the treatment of MeVOs, aiming to evaluate its efficacy and safety.
Methods Databases of two US and two UK centers were retrospectively reviewed for MeVO patients (M2-M3, anterior cerebral artery (ACA), or posterior cerebral artery (PCA)) treated with Q catheters. Outcomes were assessed as successful recanalization (modified Thrombolysis in Cerebral Infarction (mTICI) score ≥2b), first pass effect (FPE), and modified FPE (mFPE) as single pass achieving mTICI ≥2c and mTICI≥2b, respectively, and 90 day modified Rankin Scale (mRS) score.
Results 69 patients were included (median age 71 years, IQR 56–82.5; 52.2% men). Median National Institutes of Health Stroke Scale (NIHSS) score at admission was 14, and Alberta Stroke Program Early CT Score (ASPECTS) was 9. Primary (without large vessel occlusion (LVO)) and secondary (with LVO) MeVOs represented 47.8% and 52.2% of cases, respectively. Q catheters used were Q3 (47.8%), Q4 (33.3%), Q5 (10.1%), and Q6 (8.7%). mTICI≥2b was achieved in 92.8% of patients, with FPE in 47.8%, and mFPE in 68.1%. Two (2.9%) intraprocedural complications (symptomatic intracranial hemorrhage) occurred. 50% (27/54) achieved an mRS score of ≤2 at the 90 day follow-up. The median NIHSS at admission was significantly higher in secondary than in primary MeVOs (19.5 vs 12, P=0.009). The rate of mRS ≤2 at 90 days was significantly higher in primary than in secondary MeVOs (77.3% vs 31.3%, P=0.002).
Conclusions Treatment of MeVO patients with Q catheters resulted in optimal angiographic and clinical outcomes. Although angiographic results were similar between primary and secondary MeVOs, the former had less severe presenting NIHSS and better outcomes at 90 days than the latter.
- Device
- Stroke
- Thrombectomy
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What is already known on this topic
Currently, aspiration first is considered non-inferior to stent retriever based mechanical thrombectomy for large vessel occlusion stroke.
Linear tubing design of most aspiration catheters makes the suction force dependent on a large diameter to effectively retrieve clots, a limiting factor in the treatment of medium vessel occlusions (MeVOs).
Distal arteries in which MeVOs occur have a smaller caliber and can be more tortuous, increasing the risk of catheterization failure, dissection, and vessel perforation if navigation with large bore catheters is performed for clot retrieval.
What this study adds
In this international multicenter study, novel Q catheters for patients with MeVOs were used for mechanical thrombectomy.
Primary and secondary MeVOs were evenly distributed, each comprising nearly half of the cohort.
The catheters were highly effective in achieving recanalization, including first pass ones, without major complications.
How this study might affect research, practice or policy
The findings of this study have the potential to affect how MeVOs are treated with novel devices leading to low symptomatic intracranial hemorrhage rates and major complications.
Introduction
Mechanical thrombectomy (MT) became the gold standard treatment for anterior circulation large vessel occlusion (LVO) after the results of multiple randomized clinical trials.1 Modern stent retrievers played a major role in this paradigm shift in stroke care due to their high efficiency in achieving successful recanalization (>70%).2 3 Later, large bore distal aspiration catheters with improved navigability gained popularity with many defending the use of the Aspiration Direct First Pass Technique (ADAPT).4 Currently, aspiration first is considered non-inferior to stent retriever based MT for LVO.5 6 However, the linear tubing design of most aspiration catheters makes the suction force dependent on a large diameter to effectively retrieve clots.7 While this is not an issue when treating LVO, it is a limiting factor in the treatment of medium vessel occlusions (MeVOs), which represent the next frontier in endovascular management of acute ischemic stroke. Distal arteries in which MeVOs occur have a smaller caliber and can be more tortuous, increasing the risk of catheterization failure, dissection, and vessel perforation if navigation with large-bore catheters is performed for clot retrieval.8
The Q aspiration catheter (MIVI Neuroscience Inc, Minnesota USA) has a novel design that replaces the proximal three quarters of the catheter with a 104 cm long, 0.020 inch stainless steel pusher wire. This allows the 8 F guide lumen to be utilized for aspiration and has been reported to augment aspiration flow rates by up to 240%.7 In the current study, we report an international multicenter experience on the use of Q catheters for treatment of MeVOs, aiming to evaluate the effectiveness and safety of these devices.
Methods
Study population
The databases of endovascular interventions for acute ischemic stroke at four centers (two in the US and two in the UK) were retrospectively searched. The MeVO definition used for this study was occlusion of M2-M3, anterior cerebral artery (ACA), or posterior cerebral artery (PCA), and categorized as primary (without proximal LVO) or secondary (proximal LVO with a subsequent distal occlusion after recanalization attempt). M2 segments were defined as vessels beyond the first bifurcation (or trifurcation) of the insular segment of M1. Dominant M2 segments were included in the study as long as they had an occlusion. Therefore, we included all patients aged ≥18 years with primary or secondary MeVOs treated with a Q catheter.
Data extraction
Variables extracted were age, sex, comorbidities, National Institutes of Health Stroke Scale (NIHSS) score, Alberta Stroke Program Early CT Score (ASPECTS) and posterior ASPECTS, procedural details (access site, other devices used, and Q catheter size), complications, and angiographic and clinical outcomes. Angiographic outcomes were based on the modified Thrombolysis in Cerebral Infarction (mTICI) scale, with successful recanalization defined as mTICI ≥2b. The modified Rankin Scale (mRS) was used to assess prestroke functionality and clinical outcomes at 90 days. Functional independence was defined as mRS ≤2. First pass effect (FPE) and modified FPE (mFPE) were defined as single pass with Q catheter in the distal occlusion achieving mTICI ≥2c and mTICI ≥2b, respectively. Postprocedural hemorrhages were evaluated based on the Heidelberg classification, with symptomatic intracranial hemorrhage (sICH) defined as parenchymal hematoma type 2 with an increase of ≥4 points in NIHSS.9
Results
Baseline characteristics
Sixty-nine patients were included. Median age was 71 years (IQR 56–82.5) and 36 patients (52.2%) were women. Comorbidities were hypertension in 28 patients (40.6%), atrial fibrillation in 27 (39.1%), diabetes in 52 (75.4%), hyperlipidemia in 16 (23.2%), and coronary artery disease in 20 (29.4%). Sixty-five patients (94.2%) had a prestroke mRS score of ≤2 (table 1). Median NIHSS score at admission was 14 (IQR 8.5–23) and median ASPECTS was 9 (IQR 8–9). Intravenous alteplase was administered to 30 (43.5%) patients.
Summary of baseline characteristics, procedural details, and outcomes of patients
Procedural information
Access site was the femoral artery in 64 patients (92.8%) and the radial artery in 5 patients (7.2%). Thirty-three patients (47.8%) had primary MeVOs and 36 patients (52.2%) had secondary MeVOs. The occlusion locations of the primary MeVOs are listed in table 1. The proximal occlusion location in secondary MeVOs was the internal carotid artery (ICA) in 8 patients (22.2%), M1 in 25 patients (69.5%), and the basilar artery in 3 patients (8.3%). A different device was used in an attempt to recanalize the MeVO in six patients (8.7%). Q catheter sizes used were the Q3 in 33 patients (47.8%), Q4 in 23 patients (33.3%), Q5 in 7 patients (10.1%), and Q6 in 6 patients (8.7%). Balloon guide catheters were used in only five (7.2%) cases. Successful recanalization (mTICI ≥2b) was achieved in 64 patients (92.8%). FPE was achieved in 34 patients (49.3%) and mFPE in 48 patients (69.6%). Only two (2.9%) intraprocedural complications occurred: one severe vasospasm and one ICA dissection caused by an exchange wire.
Postoperative and follow-up clinical outcomes
Postprocedure ICH of any type was observed in nine patients (13%). sICH occurred in two patients (2.9%). Follow-up at 90 days was available for 54 patients, of whom 27 (50%) achieved an mRS score of ≤2. Nine patients (13%) died by 90 days.
Primary versus secondary medium vessel occlusions
Primary and secondary MeVOs were not significantly different regarding age, comorbidities, prestroke functional independence, ASPECTS, intravenous alteplase administration, access site, number of passes, use of balloon guide catheters, final mTICI, FPE, mFPE, any ICH, sICH, and mortality at 90 days (table 2). Median NIHSS at presentation was significantly higher in secondary than in primary MeVOs (19 vs 12, P=0.009). Secondary MeVOs had a significantly (P=0.01) higher rate of ACA (3% vs 22.2%) and PCA (0% vs 8.3%) occlusions, and lower rate of M2-M3 (69.4% vs 97%) occlusions than primary MeVOs. The rate of mRS ≤2 at 90 days was significantly higher in primary than in secondary MeVOs (77.3% vs 31.3%, P=0.002) (table 2). For failed thrombectomy cases, additional devices used included Catch Mini, Sofia, and Embotrap. Primary devices used for secondary MEVO cases included Sofia 6F intermediate catheter, Solitaire Stentretriever, Embotrap, Vecta 74, and Q6 MIVI catheter. The Q6 MIVI catheter was used as the primary device in only five cases for secondary MEVO cases (table 3).
Comparison of baseline characteristics, procedure details, and outcomes between primary and secondary medium vessel occlusions
Dimensions of the Q aspiration catheter
Predictors of functional independence
Univariate regression models for prediction of functional independence at 90 days were built for all variables. Secondary MeVOs (OR 0.13, 95% CI 0.03 to 0.46, P=0.002), NIHSS (OR 0.85, 95% CI 0.77 to 0.93, p<0.003), and time from puncture to recanalization (OR 0.96, 95% CI 0.93 to 0.99, P=0.024) significantly predicted reduced odds of functional independence at 90 days. A multivariate logistic regression model was then built with these three variables, and time from puncture to recanalization (OR 0.95, 95% CI 0.92 to 0.98) and NIHSS (OR 0.76, 95% CI 0.62 to 0.094, P=0.011) independently predicted reduced odds of functional independence at 90 days. Twenty-one patients (38.9%) in the mFPE group achieved good functional outcome at 90 days versus 15 (27.8%) in the FPE group. This difference was found to be statistically non-significant (P=0.221)
Discussion
We have reported an international multicenter experience of MT using the novel Q catheters for patients with MeVOs. Primary and secondary MeVOs were evenly distributed, each comprising nearly half of the cohort. The catheters were highly effective in achieving recanalization, including first pass ones, without major complications. Overall, our patients achieved a high rate of functional outcome at 90 days. However, we found that primary MeVOs presented with lower severity and achieved better outcomes than secondary ones. Furthermore, secondary MeVOs and higher stroke severity were found to be independent predictors of worst outcomes. The current study is the largest series of patients treated with the novel Q catheters.
Aspiration thrombectomy has been demonstrated to have similar efficacy and safety to stent retriever based thrombectomy for LVO in multiple studies and is currently accepted as non-inferior.4 5 Moreover, the aspiration first strategy has been proposed to have financial advantages over stent retriever first.10 Comparisons of aspiration versus stent retriever first in MeVOs have been less extensively performed. In a subanalysis of the Treatment for Primary Medium Vessel Occlusion Stroke (TOPMOST) study evaluating 141 patients with primary isolated P2 and P3 occlusions, the investigators reported that aspiration first and stent retriever first strategies had similar rates of FPE (aspiration 53.7% vs stent retriever 44%, P=0.297) and mRS score was 0–1 at 90-days (aspiration 60.5% vs stent retriever 68.6%, P=0.4).11 Barchetti et al performed a meta-analysis of 494 patients, with a distal occlusion definition similar to ours (A2-A3, M2-M3, P1-P2), comparing ADAPT versus 0.017 microcatheter compatible stent retrievers.12 The authors found comparable recanalization rates, but lower functional independence and higher mortality rate in stent retriever patients.12
Suction force in aspiration thrombectomy depends on the area in contact with the clot surface. Therefore, higher suction forces are expected with larger bore catheters. However, the diameters of such catheters are not compatible with smaller caliber vessels, such as the ACA, PCA, and M2-M3. In these locations, either smaller bore catheters or stent retriever have to be used, which have diminished odds of recanalization and increased cost of treatment, respectively. The design of Q catheters eliminates the proximal part of the catheter and replaces it with a wire, allowing a larger inner diameter guide to be connected, while the tip remains small, maximizing suction force in distal vessels.7 No direct comparisons have been performed between standard aspiration catheters compatible with smaller caliber of distal occlusions versus the Q catheter design. In the literature, the meta-analysis of Barchetti et al reported 2b–3 recanalization rates in distal occlusions of approximately 80%, in which most studies used standard aspiration catheters.12 Nevertheless, details such as number of passes and use of adjunctive techniques prior to final recanalization grade in case of failure of aspiration are important for better comparison. In our study, the rate of 92.8% successful recanalization was achieved without the use of adjunctive techniques after the Q catheter was attempted. In a study by Vargas et al evaluating ADAPT using 5MAX, 4MAX, and 3MAX catheters in distal occlusions, the rate of 2b–3 recanalization was 77.1% in aspiration alone without further adjunctive techniques.13 In their study, however, no breakdown of primary and secondary MeVOs was performed.
In addition to reporting a large experience with the novel Q catheters, our study also provided information for the scarce literature on primary and secondary MeVOs. Goyal et al reported that secondary MeVOs can occur due to spontaneous clot fragmentation, thrombolytic drug induced fragmentation (eg, post-intravenous alteplase administration), or mechanical induced fragmentation (eg, during clot retrieval attempts in mechanical thrombectomy).14 Given that in the context of our study and other series of MeVOs treated with MT it is often not possible to determine the mechanism of secondary MeVOs, we categorized as secondary any MeVO with a proximal LVO. Importantly, our study supports a few assumptions described in the literature about secondary MeVOs.8 14 For example, we found that secondary MeVOs had greater severity based on NIHSS at admission, longer time to recanalization, and worse outcomes at 90 days. Conversely, it would make sense for secondary MeVOs to have more extensive infarctions, as previously described for MeVOs with discrepant infarct, but we did not observe worse ASPECTS in secondary MeVO patients.15 It has been speculated that secondary MeVOs could have a higher risk of hemorrhagic conversions when treated, but we observed similar rates for any ICH and sICH in our primary and secondary MeVO patients.14 Moreover, the hypothesis that secondary MeVOs could be more fragile and prone to further fragmentation on treatment was also not observed in our study, as the rates of recanalization were similar between primary and secondary occlusions.14 Interestingly, secondary MeVO status did not independently predict worse outcomes when built in the multivariable regression model along with time from puncture to recanalization and NIHSS. This may be a suggestion that even primary MeVOs can have poor outcomes if time to recanalization is delayed, therefore highlighting the importance of efficient thrombectomy devices to achieve first pass recanalization in these patients.
Our study had limitations. This was a retrospective observational study with a limited population of interest. Different management protocols may have been followed across the institutions, which were from two different countries, therefore limiting technical consistency. Although much evidence exists regarding the potential benefit of balloon guide catheters in LVO strokes, only 7.2% of our cases were performed using these. This does not provide enough evidence to draw any conclusions. Also, since four different centers contributed to data for this study, varying operator preference led to dismal use. Furthermore, patients were treated by highly experienced operators at all centers, reducing the generalizability of our findings. The results of this study must be approached with caution.
Conclusions
Treatment of acute ischemic stroke patients with MeVOs using the novel Q catheters resulted in high rates of successful recanalization, mFPE and FPE, low complication rates, and high rates of functional independence at 90 days. Secondary MeVOs were found to have worse severity at presentation and worse outcomes at 90 days. Finally, only worse severity and longer time from puncture to recanalization were predictors of poor outcomes in the overall cohort.
Ethics statements
Patient consent for publication
Ethics approval
This study was approved by the local institutional review boards of the participating centers: University at Buffalo Institutional Review Board-STUDY00003261; Royal London Hospital-13199; North Bristol NHS Trust-QI10616; University of Alabama at Birmingham-300010394; Queen's Medical Centre Nottingham University Hospital NHS Trust-13199; and University of South Florida-STUDY003508. The local institutional review boards waived the need for patient consent.
References
Footnotes
X @andremonteiromd, @hldmak, @amdbaig, @PermeshSD
Presented at This study was previously presented as a poster at SNIS 19th Annual Meeting (Toronto, Canada), P-030 Mechanical thrombectomy in medium vessel occlusions using the novel aspiration MIVI Q catheters: an international multicenter experience.
Contributors Conception and design: AM, WB, and AHS. Acquisition of the data: AAB, HLDM, JW, JJ, PSD, and PB. Formal analysis and investigation: all authors. Statistical analysis: AM and AAB. Drafting the manuscript: AM, AAB, WB, and AHS. Critically revising the manuscript: all authors. Reviewed the submitted version of the manuscript: all authors. Study supervision: WB and AHS.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial, or not-for-profit sectors.
Competing interests HLDM: consulting fees for Stryker, MicroVention, BALT, Cerenovus, Perfuze, and Brainomix; stock or stock options from Perfuze; other financial or non-financial interests in Proctor-MicroVention, Balt, and Sela Medical. JW: support for present manuscript from MIVI, charged for time to pull data from prospective database; consulting fees from MIVI, consulting on marketing material; payment or honoraria from MIVI, educational talks to new users. JJ: consulting fees from MIVI and Cerenovus; fees for participation on an advisory board for Protara. PB: consulting fees from Perflow Medical, Brainomix, Balt, Stryker, Phenox, and Neurovasc; payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Brainomix, Perflow Medical Stryker, and Cerenovus; support for attending meetings and/or travel from Cereflow (LINCC 2022); stock or stock options in Cerenovus and Spartan Medical. MM: consulting fees (not related to the present work) from Cerenovus and Medtronic; NIH grant support R21NS109575 (principal investigator; not related to present work); leadership or fiduciary role in other board, society, committee, or advocacy group, paid or unpaid, JNIS editorial board (technical videos editor); stock or stock options in BrainQ, Endostream, Serenity Medical, and Synchron. WB: consulting fees for MIVI (consulting medical director), Medtronic, Stryker, MicroVention, Cerenovus, Imperative Care, Balt, and Rapid; stock or stock options in Superior Medical Experts, Nested Knowledge, and Piraeus Medical; other financial or non-financial interests in NIH, Cerenovus, and Brainomix (research funding). AHS: consulting fees for Amnis Therapeutics, Apellis Pharmaceuticals, Boston Scientific, Canon Medical Systems USA, Cardinal Health 200, Cerebrotech Medical Systems, Cerenovus, Cerevatech Medical, Cordis, Corindus, Endostream Medical, Imperative Care, InspireMD, Integra, IRRAS AB, Medtronic, MicroVention, Minnetronix Neuro, Peijia Medical, Penumbra, Q’Apel Medical, Rapid Medical, Serenity Medical, Silk Road Medical, StimMed, Stryker Neurovascular, Three Rivers Medical, VasSol, and Viz.ai; leadership or fiduciary role in other board, society, committee, or advocacy group: secretary on board of the Society of NeuroInterventional Surgery 2020-2021, chair of Cerebrovascular Section of the AANS/CNS 2020-2021; stock or stock options in Adona Medical, Amnis Therapeutics, Bend IT Technologies, BlinkTBI, Borvo Medical, Bridgewater Ventures, Cerebrotech Medical Systems, Cerevatech Medical, Code Zero Medical, Cognition Medical, Collavidence, CVAID, E8, Endostream Medical, Galaxy Therapeutics, Imperative Care, InspireMD, Instylla, International Medical Distribution Partners, Launch NY, Neurolutions, NeuroRadial Technologies, NeuroTechnology Investors, Neurovascular Diagnostics, Peijia Medical, PerFlow Medical, Piraeus Medical, Q’Apel Medical, QAS.ai, Radical Catheter Technologies, Rebound Therapeutics Corp (purchased 2019 by Integra Lifesciences Corp), Rist Neurovascular (purchased 2020 by Medtronic), Sense Diagnostics, Serenity Medical, Silk Road Medical, Sim & Cure, SongBird Therapy, Spinnaker Medical, StimMed, Synchron, Three Rivers Medical, Truvic Medical, Tulavi Therapeutics, Vastrax, VICIS, Viseon, Whisper Medical, and Willow Medtech; other financial or non-financial interests: National PI/Steering Committees for Cerenovus EXCELLENT and ARISE II Trial, Medtronic SWIFT PRIME, VANTAGE, EMBOLISE, and SWIFT DIRECT Trials, MicroVention FRED Trial and CONFIDENCE Study, MUSC POSITIVE trial, Penumbra 3D Separator Trial, COMPASS Trial, INVEST Trial, MIVI neuroscience EVAQ Trial, Rapid Medical SUCCESS Trial and InspireMD C-GUARDIANS IDE Pivotal Trial.
Provenance and peer review Not commissioned; externally peer reviewed.