Number of passes in mechanical thrombectomy: where is your limit?

Direct to Thrombectomy.

Endovascular treatment for acute ischemic stroke patients with large vessel occlusion (LVO) has been established as a promising clinical intervention within a late time window of 6-24 h after symptom onset. Patients with slow progression, however, may still benefit from endovascular treatment beyond the 24-h time window (very late window). The aim of this study is to report insight into the potential clinical benefits of endovascular treatment for acute ischemic stroke beyond 24 h from symptom onset. A retrospective analysis was performed on consecutive patients undergoing endovascular treatment for acute anterior circulation LVO ischemic stroke beyond 24 h. Participants were recruited between July 2019 and November 2020. Patients were selected based on the DAWN/DEFUSE 3 criteria (Perfusion-RAPID, iSchemaView) and patients receiving treatment beyond 24 h were compared to a group of patients receiving endovascular treatment between 6 and 24 h after symptom onset. The primary outcome was the proportion of patients with functional independence at 90 days (modified Rankin Scale score of 0-2). The secondary outcomes were shift modified Rankin Scale (mRS) analysis and successful reperfusion was defined by thrombolysis in cerebral infarction (TICI) 2b-3 on the final procedure. Safety outcomes were symptomatic intracranial hemorrhage and death at the 90-day follow-up. Propensity score (PS)-matched analyses were employed to rectify the imbalanced baseline characteristics between the two groups. A total of 166 patients were recruited with a median age of 63.0 (56.0-69.0) and 28.9% of all patients were females. Patients in the beyond 24-h group had a longer onset-to-groin time (median = 27.2 vs 14.3 h, p < 0.001) than those in the 6- to 24-h group. There were no statistically significant differences between the two groups in National Institutes of Health Stroke Scale (NIHSS) (median = 12.0 vs 15.0, p = 0.37), perfusion imaging characteristics (core: median = 11.0 vs 9.0 mL, p = 0.86; mismatch volume: median = 106.0 vs 96.0, p = 0.44; mismatch ratio = 6.46 vs 7.24, p = 0.91), and perfusion-to-groin time (median = 72.5 vs 76.0 min, p = 0.77). No significant differences were noted among patients between the two groups in the primary endpoint functional independence analysis (50.0% vs 46.6%, p = 0.77) and in the safety endpoint analysis: mortality (15.0% vs 11.0%, p = 0.71) or symptomatic hemorrhage (0% vs 3.42%, p > 0.999). In PS-matched analyses, there were no significant differences among patients between the two groups in functional independence (50.0% vs 54.8%, p = 0.74), mortality (16.7% vs 9.68%, p = 0.50), or symptomatic hemorrhage (0% vs 6.45%, p = 0.53). Endovascular treatment can be performed safely and effectively in LVO patients beyond 24 h from symptom onset when selected by target mismatch profile. The clinical outcome of these patients was comparable to those treated in the 6- to 24-h window. Larger studies are needed to confirm these findings.

Background: Mechanical thrombectomy (MT) is the standard treatment for acute ischemic stroke with large-vessel occlusion (LVO), but regional data from Thailand are limited, particularly regarding factors influencing long-term outcomes. Objective: To evaluate 90-day functional independence (modified Rankin Scale [mRS] ≤2) after MT at a single center in Eastern Thailand and identify predictors of functional independence. Materials and Methods: We retrospectively analyzed all MT procedures from March 2019 to December 2023 at Bangkok Pattaya Hospital. Inclusion followed AHA guidelines and DAWN criteria, with adjustments for early presentations. Baseline demographics, imaging, angiography, and procedural data were collected. The primary endpoint was functional independence at 90 days. Associations were examined using univariate and multivariable logistic regression. Results: Of 141 MT cases, 132 were included (mean age 64.2 years; 87.8% Thai). Anterior circulation strokes accounted for 87.9%. Successful reperfusion (mTICI ≥2b) occurred in 81.1%, and functional independence at 90 days in 70.5%. Lower baseline NIHSS showed borderline association with functional independence (p=0.059). Post-procedural aICH or no ICH significantly reduced odds of functional independence compared with sICH (aICH: OR 0.09, 95% CI 0.02-0.45, p=0.006; no ICH: OR 0.05, 95% CI 0.01-0.20, p&lt;0.001). Age, sex, atrial fibrillation, onset-to-recanalization time, and first-pass success were not significant predictors. sICH was more frequent with IVT+MT than MT alone (17.4% vs. 1.6%, p=0.006). Conclusion: MT at our center achieved high reperfusion and functional independence rates comparable to international benchmarks. Hemorrhagic transformation was a strong predictor, whereas age, sex, and treatment strategy were not. Careful imaging selection and individualized bridging therapy may optimize outcomes.

IntroductionMechanical thrombectomy with stent retrievers is superior to medical management in acute ischemic stroke due to large vessel occlusion (LVO). The Direct Aspiration First Pass (ADAPT) and combined mechanical/aspiration thrombectomy...

Background Mechanical thrombectomy has revolutionized the treatment of acute ischemic stroke. Although a few studies have explored the correlation between thrombus histopathology and the number of passes required, the relationship remains unclear. The composition of the thrombus significantly influences the complexity of the procedure. Research has shown that erythrocyte-rich clots are associated with better reperfusion outcomes and fewer passes, whereas fibrin-rich clots are more challenging to retrieve and yield poorer outcomes. This study aims to investigate the association between thrombus histopathology and the number of passes during mechanical thrombectomy. Methods This retrospective observational study included 60 patients undergoing mechanical thrombectomy. Thrombus samples were analyzed histologically using hematoxylin-eosin staining and classified as either erythrocyte-rich (>50% erythrocytes) or fibrin-rich (>50% fibrin). The number of thrombectomy passes and patient demographics were recorded. Statistical analysis was performed to identify associations. Results RBC-rich thrombi were associated with fewer passes (p=0.035). Additionally, patients aged 45-65 years had a higher proportion of fibrin-rich clots, which required more passes (p=0.021). Conclusion This study demonstrates a significant association between thrombus histopathology and the number of passes during mechanical thrombectomy. Understanding thrombus composition may aid in tailoring therapeutic approaches and improving patient outcomes. Overall, thrombus composition was significantly correlated with the number of passes, with erythrocyte-rich thrombi requiring fewer attempts for successful retrieval.

Should Primary Stroke Centers Perform Advanced Imaging?

Section Editors: Marc Fisher MD Antoni Davalos MD The Food and Drug Administration (FDA) evaluates applications for new human drugs, biologics, and complex medical devices. Companies must obtain FDA approval to legally market these products. In August, the FDA gave Concentric Medical clearance to market its Merci Retriever system to “remove blood clots from the brain in patients experiencing an ischemic stroke.” Given that the FDA is charged with “protecting the public health by assuring the safety, efficacy, and security of… biological products and medical devices…, ” “advancing public health by helping to speed innovations that make medicines … more effective, safer, and more affordable,” and “helping the public get the accurate, science-based information they need to use medicines … to improve their health,”1 the FDA’s decision to approve the Merci Retriever system is of concern. The pathways to approval are reviewed by Felten et al in the accompanying article and are outlined in Figure 1. Figure 1. Potential pathways for device approval. The decision to approve the Merci Retriever was based on data from the MERCI (Mechanical Embolus Removal in Cerebral Ischemia) Trial; the approval was granted through the 510(k) process. The Merci Retriever system includes a flexible nickel titanium (nitinol) wire that obtains a helical shape once it is passed through the tip of the guidance catheter. In practice, the catheter/wire is passed distal to the thrombus, the catheter is removed, and the helical configuration assumed by the wire; the clot is then trapped in the helix and withdrawn from the vasculature (Figure 2). The 510(k) clearance means that the Merci Retriever was felt to be substantially equivalent to a predicate device. In this case, the predicate device was the Concentric Retriever, which itself received 510(k) clearance by the FDA in May 2001 for “use in …

BackgroundHigh-quality evidence exists for mechanical thrombectomy (MT) treatment of acute ischemic stroke (AIS) due to large vessel occlusion of the anterior circulation (AC-LVO). The evidence for MT treatment of posterior...

A multicenter randomized clinical trial of endovascular treatment for acute ischemic stroke caused by proximal arterial occlusion in the anterior circulation.

Large Vessel Occlusion Strokes After the DIRECT-MT and SKIP Trials: Is the Alteplase Syringe Half Empty or Half Full?

Stress Hyperglycemia Could Influence Futile Recanalization in Patients Who Undergo Mechanical Thrombectomy for Stroke Caused by Large Vessel Occlusion.

High-quality evidence exists for mechanical thrombectomy (MT) treatment of acute ischemic stroke (AIS) due to large vessel occlusion of the anterior circulation (AC-LVO). The evidence for MT treatment of posterior circulation large vessel occlusion (PC-LVO) is weaker, largely drawn from lower quality studies specific to PC-LVO and extrapolated from findings in AC-LVO, and ambiguous with regards to technical success. We performed a systematic review and meta-analysis to compare the technical success and functional outcomes of MT in PC-LVO versus AC-LVO patients. We identified comparative studies reporting on patients treated with MT in AC-LVO versus PC-LVO. The primary outcome of interest was thrombolysis in cerebral infarction (TICI) ≥ 2b. Secondary outcomes included rates of TICI 3, 90-day functional independence, first-pass-effect, average number of passes, and 90-day mortality. A separate random effects model was fit for each outcome measure. Twenty studies with 12,911 patients, 11,299 (87.5%) in the AC-LVO arm and 1612 (12.5%) in the PC-LVO arm, were included. AC-LVO and PC-LVO patients had comparable rates of successful recanalization [OR = 1.02 [95% CI: 0.79-1.33], p = 0.848). However, the AC-LVO group had greater odds of 90-day functional independence (OR = 1.26 [95% CI: 1.00; 1.59], p = 0.050) and lower odds of 90-day mortality (OR = 0.58 [95% CI: 0.43; 0.79], p = 0.002). MT achieves similar rates of recanalization with a similar safety profile in PC-LVO and AC-LVO patients. Patients with PC-LVO are less likely to achieve functional independence after MT. Future studies should identify PC-LVO patients who are likely to achieve favourable functional outcomes.

Commentary

Introduction: Mechanical thrombectomy (MT) is a primary treatment for acute ischemic stroke due to large vessel occlusions. While effective, 20-40% of patients experience hemorrhagic transformation (HT), and around 50% fail to achieve favorable functional outcomes. Transcranial Doppler (TCD) is a non-invasive and cost-effective method for real-time monitoring of hemodynamic status following MT. However, the prognostic value of TCD parameters in predicting HT and poor functional outcome is unclear. We performed a systematic review and meta-analysis of 4 TCD parameters (mean flow velocity (MFV), MFV index, peak systolic velocity (PSV), and pulsatility index (PI) in patients with and without HT and favorable vs poor functional recovery (modified Rankin Scale (mRS) 0-2 vs 3-6). Methods: PubMed, Embase, and Scopus were searched on July 25, 2024 to identify observational studies in which TCD parameters were measured within 48 hours from successful MT (Thrombolysis in Cerebral Infarction 2b–3) of anterior circulation. Risk of bias assessment was performed using a standardized tool tailored for TCD studies. The standardized mean difference (Hedges’ g) with 95% CI and risk ratios (RRs) with 95% CI were calculated using random-effects models. The review was prospectively registered on PROSPERO (registration number CRD42024575381). Results: Eleven studies met inclusion criteria. No study had high risk of bias. MFV and MFV index were higher in patients with HT+ compared with HT- (Hedges' g = 0.42 and 0.54, p = 0.015 and 0.005, respectively). Patients with MFV index ≥1.3 showed a higher risk of all HT (RR = 2.01, 95% CI = 1.27–3.17, p = 0.003), symptomatic HT (RR, 4.68; 95% CI,1.49–14.65, p=0.008), and poor functional recovery at 90 days (RR, 1.66; 95% CI,1.32–2.08, p&lt;0.001), respectively. There was no difference in mean PSV (p=0.1) and PI (p=0.3) among groups with and without HT. Conclusion: Our study highlights the prognostic value of TCD parameters, particularly MFV index, in predicting HT, symptomatic HT, and poor functional recovery after successful MT in the anterior circulation. Our findings were limited by low number of studies. Large-scale and multi-center studies are needed to confirm these findings and validate the MFV index as a reliable predictor to improve post-thrombectomy care.

Background and Purpose: Intracranial hemorrhage (ICH) presents as a major complication for patients undergoing endovascular treatment (EVT) for acute ischemic stroke (AIS). Our study aims to assess the risk and correlation with the number of passes with a stentriver involved in EVT and hemorrhagic transformation. Methods: We utilized our endovascular database and analyzed all the patients admitted from 2012-2017, who underwent EVT with stentrievers. We collected baseline demographics, clinical characteristics, admission NIHSS, and modified Rankin Scale (mRS) at discharge, as well as groin puncture and recanalization times. The number of stentriver passes during each procedure as well as presence of ICH post procedure were recorded. A logistic regression analysis was done to determine the association between hemorrhagic transformation and number of passes. Results: 277 patients (mean age 71.6 ± 12.6 years; 52% female) with AIS underwent EVT with stentrievers. There was no difference in baseline demographics. (Table 1) Of the 277 patients, 47 (17.0%) were diagnosed with ICH after EVT. Ninety-day mortality was higher in patients with ICH than in patients without ICH (15.7% vs 42.6%; P=.001). On multivariate analysis, the number of passes with a stentriever were not significantly associated with ICH after EVT (OR, 1.3; 95% CI, 0.89-1.9). There was no significant difference in rates of intracranial hemorrhage occurrence with ≥5 passes (OR, 5.0; 95% CI, 0.31-82.4). Conclusions: Our study shows that endovascular treatment with multiple passes of a stentreiver does not increase the incidence of symptomatic hemorrhage in AIS, even up to 5 passes. Large prospective studies are warranted to study the factors that lead to hemorrhagic transformation in AIS.