Abstract TP309: Does Procedural Technique and Experience Improve Outcomes in M2 Thrombectomy?

Introduction: Recent negative trials for M2 and beyond endovascular thrombectomy (EVT) have led to study design changes in new or re-starting studies. Some of these changes include increased usage of aspiration versus stent-retrievers. Here, we analyze temporal trends in EVT for M2 vs. M1 MCA occlusions at our institution to evaluate changes in procedural technique and assess whether these changes were associated with improved technical outcomes. Methods: From our prospectively collected multicenter registry from four comprehensive stroke centers in the Greater Houston area, we analyzed patients with LVO ischemic stroke who underwent EVT for M1 or M2 occlusions between January 2020 and June 2024. Cases with tandem occlusions or incomplete data were excluded. The primary outcome was first-pass effect (FPE) defined as mTICI 2b-3 after a single pass. Techniques were classified as stent-retriever alone (SR), contact aspiration alone (CA) or combined (CT). Secondary outcomes were annual trends in final mTICI 2b–3, 90-day good outcome (mRS 0–2), ICH, sICH, mortality, and total number of passes. Analyses used multivariate logistic regression for binary outcomes, multinomial regression for EVT techniques, and Poisson regression for number of passes, adjusted for age and NIHSS. Results: Among 629 patients that met the inclusion criteria, median age was 68 years (IQR54-78), 52.9% were female, and median NIHSS was 16 (IQR10-20). 460 (73.13%) presented with M1 occlusions and 169 (26.87%) with M2. Among patients with M2 occlusions, we observed a significant decrease in SR and increase in CA from 2020 – 2024 (aRRR=0.490.35 - 0.70, Figure 1). Over this time period, we found no statistically significant changes in FPE (aOR=1.000.78-1.27), final TICI 2b (aOR=0.94 0.63-1.40), 90d mRS 0-2 (aOR 0.90 0.66-1.24), ICH (aOR 1.31 0.79-2.15), or sICH (aOR 0.70 0.35-1.37). Rates of FPE in patients with M2 occlusion were similar to those in patients with M1 occlusions (63.04% vs 57.99%, aOR=0.94 0.71,1.25). Similarly, rates of final TICI were similar in M1 occlusion EVT procedures (0.96 0.59,1.54). Conclusion: In this multi-center cohort over a recent 4.5 year time period, we observed a transition from SR to CA for treatment of M2 occlusions. Despite these changes, we found no differences in FPE or final TICI, nor in safety or clinical outcomes. These findings suggest transitioning to CA from SR for M2 occlusions is not associated with improved technical outcomes.