Background and purpose Increasing time from symptom onset to emergency department arrival may incur greater ischemic injury and decreased likelihood of good outcomes after acute stroke therapy. The impact of time may be assessed bythe extent of acute CT changes, status of collateral vessels, and clinical outcomes.

Methods The SOLITAIRE FR With the Intention For Thrombectomy (SWIFT) trial comparing two neurothrombectomy treatments was analyzed by time, Alberta Stroke Program Early CT Scores (ASPECTS), angiographic collaterals, and 90-day modified Rankin Scale outcomes. We determined the interaction of time with ASPECTS, collateral grade, reperfusion, and clinical outcomes, with established determinants of angiographic and clinical outcomes as covariates.

Results 137 patients (52% female) of mean age 67±12 years and median pretreatment NIH Stroke Scale score 18 (range 8–28) were enrolled. Median onset to door (OTD) time was 180 min (IQR 95–250). Presentation within 3 h of last known well was associated with absence of any prestroke disability and presence of atrial fibrillation but was unrelated to age, sex, other vascular risk factors, deficit severity, glucose level, or blood pressure. Worse collaterals were noted with longer OTD intervals: collateral grade 0–1 (n=32): mean 232±84 min; grade 2 (n=48): 164±99 min; grade 3 (n=35): 155±104 min; grade 4 (n=4): 54±16 min (p<0.001). Later presentation was associated with more extensive early infarct imaging changes (median ASPECTS 8 (IQR 7–9) >3 h vs 9 (IQR 8–10) <3 h, p=0.015). Multivariable analyses identified time >3 h as the only predictor of extensive infarct on imaging (ASPECTS ≤7), p=0.003. Earlier presentation was strongly associated with better 90-day modified Rankin Scale outcomes (p<0.001).

Conclusions Time was a critical factor in successful clinical outcomes for neurothrombectomy in the SWIFT trial. Shorter times to presentation were associated with better collaterals, smaller established infarcts, and better clinical outcome after revascularization.