Abstract P481: Time to Reperfusion Determines Clinical Outcomes Independent of Post Thrombectomy Infarct Volume
Introduction: Late time window thrombectomy trials demonstrated that good functional outcomes can be achieved up to 24 hours from stroke onset in Slow Progressors (small infarct volume and large penumbral volume). In this study, we aim to investigate whether early (<6 hours) recanalization leads to superior functional outcomes compared to delayed recanalization (>6 hours) amongst patients with similar 24-hour infarct volumes post thrombectomy. Methods: We performed a retrospective analysis of a prospectively maintained LVO stroke thrombectomy database across 3 comprehensive stroke centers. Demographic, clinical, radiological, and outcomes data were analyzed. Inclusion criteria were witnessed onset anterior circulation LVO [internal carotid or middle cerebral artery M1] strokes with a good baseline mRS score (0-1) having achieved success recanalization [mTICI 2b-3] and 24-hour infarct volume of ≤10 ml on CT head or MRI. Univariate and multivariate analysis of the impact of time to recanalization on clinical outcomes was performed. Results: Of the 499 LVO strokes undergoing thrombectomy, 30% (148) met inclusion criteria. Mean age was 70 ±14 and median NIHSS score was 17 (14-21). Early recanalization (<6h) was achieved in 65% (96) of patients. Baseline demographic (age: 73 vs 74, p=0.80) and clinical characteristics (NIHSS:16.5 vs 17, p=0.52; 24-h infarct volume: 4.4 vs 4.2 ml, p=0.60) were comparable between early versus late recanalization patients. Rates of early clinical improvement (24-h NIHSS <6) (71% vs 39%, p=0.0007) and mRS 0-2 at 90 days (68% vs 48%, p=0.019) were higher in early recanalizers compared to late recanalizers. Multivariate analysis including age, NIHSS, time to recanalization, and 24-hour infarct volume identified early recanalization as an independent predictor of mRS 0-2 at 90 days (OR-2.41 95% CI 1.89-4.50). Every 1-hour increase in time to recanalization decreased the odds of 90-day mRS 0-2 by 2.2%. Conclusion: Among patients with similar 24-hour infarct volume post thrombectomy (≤10 ml), shorter time to successful recanalization is associated with significantly higher rates of early clinical improvement and mRS 0-2 at 90 days. Increased penumbral ischemic time may have an impact on outcomes post stroke thrombectomy.