Effect of time on reperfusion in acute ischemic stroke treated with thrombolysis within the 4.5-hour window: a secondary analysis of the AcT Trial

Background It is unclear if revascularization therapies become less effective at recanalizing occlusions over time. We evaluated the association between time metrics and successful reperfusion in patients treated with thrombolysis for anterior circulation large vessel occlusion (LVO) strokes. Methods We included LVO patients from the AcT (Alteplase compared to Tenecteplase) trial who underwent digital subtraction angiography. Logistic regression was performed to determine associations between time metrics and reperfusion outcomes: initial successful reperfusion (eTICI score >= 2b on first run), initial eTICI score, first pass effect (final eTICI 2b-3 after one thrombectomy pass), and final eTICI score. Models adjusted for age, sex, baseline NIHSS, occlusion location, treatment allocation and needle-to-groin time. Results Among 471 patients, 46 (9.7%) achieved initial successful reperfusion (initial eTICI >= 2b) post-thrombolysis and prior to thrombectomy. Median age was 73 years, 50.7% were female; M1 occlusions were most common (40.6%). Onset-to-needle (median 110 vs 105 min; p = 0.055), onset-to-groin (157 vs 155 min; p = 0.376), and needle-to-groin times (46 vs 39 min; p = 0.394) did not differ between patients with vs without initial successful reperfusion. Onset-to-needle time was not associated with initial successful reperfusion (aOR 1.00 per 10-min increase; 95% CI 0.96-1.05). Onset-to-groin time was also not associated with first-pass effect (aOR 0.99; 95% CI 0.97-1.02) or final eTICI (aOR 1.00; 95% CI 0.98-1.02). Conclusion Time from symptom onset was not significantly associated with angiographic reperfusion outcomes among patients with anterior circulation LVO stroke treated within the 4.5 h window. Further studies should explore this relationship across wider time windows, stroke subtypes, and treatments.