Abstract WP70: Reperfusion Therapy in Posterior Circulation Large Vessel Occlusion With Perfusion Deficits May Be Safe and Improve Outcomes Beyond 4.5 Hours

Introduction: Whether reperfusion therapy is safe and efficacious in acute ischemic strokes (AIS) due to posterior circulation large vessel occlusions (PCLVO) beyond 4.5 hrs is unknown. Methods: A retrospective analysis of AIS due to PCLVO presenting to a comprehensive stroke center up to 24 hrs from last known well. Patients were stratified based on the treatment received into reperfusion therapy (IV-tPA and/or endovascular thrombectomy) and no reperfusion therapy. All patients received CT/CTA and CT perfusion with RAPID mismatch determination. Functional independence (90 day mRS 0-2) and sICH were primary and secondary outcomes. The two groups were compared in the overall cohort in an ordinal logistic regression and in a propensity matched analyses. Results: Between 8/2017 and 5/2019, 52 patients were included [reperfusion = 23(44%) vs no-reperfusion=29(56%)]. Reperfusion rate beyond 4.5 hours was 26% (6/23). The two groups were similar at baseline except for larger perfusion delays (Tmax>6s) volume [median (IQR), 16 (0, 46) vs. 0 (0, 25) cc, p=0.03], and higher presentation NIHSS [median (IQR), 10 (5, 21) vs. 4 (1, 8), p=0.004] in the reperfusion group. Reperfusion was associated with higher functional independence rates 10 (43%) vs. 8 (28%), p=0.23 (fig 1), and a trend for a shift towards better outcomes adj cOR 1.89, 95% CI=0.59-6.13, p=0.29. There was no difference in sICH rates 9% vs. 0%, P=0.19. In a propensity matched analysis on NIHSS and perfusion deficit of 14 pairs, reperfusion was associated with statistically significant higher mRS 0-2 rates 9 (64%) vs. 1 (7%), p=0.004 (fig 2). Functional independence rates did not differ in the reperfusion group in relation to time (47% Conclusion: PCLVOs with more severe strokes and large perfusion deficits were more likely to receive reperfusion which was associated with a shift towards better outcomes both earlier and beyond 4.5 hours without worsening safety outcomes.