Impact of time from symptom onset to puncture, and puncture to reperfusion, in endovascular therapy in the late time window (>6 hours).

Background- Increased times from symptom onset to puncture (TSOP) and from puncture to reperfusion (TPTR) are associated with worse outcome in ischemic stroke patients treated with endovascular therapy (EVT) in the early time window (<6 hours). However, these associations are less described in the late window (>6 hours), where patients may benefit from EVT because of a more favorable imaging profile (late window paradox). We sought to compare the effect of these timeframes between these two periods on efficacy and safety outcomes.Methods- The ETIS Registry (Endovascular Treatment in Ischemic Stroke) is an ongoing, prospective, observational study in 21 centers that perform EVT in France. We included adult patients with an anterior occlusion, successfully treated by EVT (mTICI 2b-3) between January 2015 and June 2023, with a known time of stroke onset. The cohort was divided into 2 groups according to the TSOP (≤6h vs >6h). Primary outcome was favorable outcome (modified Rankin Scale 0-2 at 90 days).Results- 7,516 patients were included, with 5,936 patients being treated ≤6h and 1,580 >6h. In the early window, TSOP and TPTR were associated with worse outcomes at 90 days (adjusted OR=0.68 per hour; 95%CI, 0.64-0.73; p<0.001 and aOR=0.92 per 10 minutes increment; 95%CI, 0.90-0.94, p<0.001, respectively). TSOP was not associated with worse outcomes at 90 days in the late window (p=0.955), but TPTR was associated with worse outcomes (aOR=0.91 per 10 minutes increment; 95%CI, 0.86-0.96, p=0.001), every 10 additional minutes in TPTR being associated with a 1.7% (95%CI, 0.6%-2.7%) decreased probability of favorable outcome.Conclusions- Only EVT procedural time is associated to unfavorable outcomes at 90 days in late window patients. These results highlight how the late window paradox may end at the start of EVT and underscore the need for timely management, particularly for the EVT, even for late window patients with a presumed more favorable imaging profile.