Mechanical Thrombectomy and Final Infarct Volume in Medium or Distal Vessel Occlusion Stroke

Importance: Imaging-based end points may enhance the understanding of endovascular treatment (EVT) outcomes in patients with medium- or distal-vessel occlusion stroke. Objective: To investigate the outcomes of endovascular treatment (EVT) in addition to best medical treatment (BMT) compared with BMT alone on the volume of brain tissue initially at risk preserved in patients with a medium or distal vessel occlusion stroke. Design, Setting, and Participants: Post hoc imaging analysis of the Endovascular Treatment for Stroke Due to Occlusion of Medium or Distal Vessels (DISTAL) trial, a multicenter randomized clinical trial with blinded end point assessment conducted at 55 hospitals in 11 countries from December 2021 through July 2024, with clinical follow-up at 90 days. Patients with baseline perfusion imaging and follow-up imaging at 24 hours were included. Interventions: EVT plus BMT compared with BMT alone. Main Outcomes and Measures: Primary outcome was calculated as the difference in volume of tissue at risk and the final infarct volume divided by the tissue at risk (change in Vrel). We defined a Vrel of 0.8 or greater as a good imaging outcome, meaning that at least 80% of the brain tissue initially at risk was not infarcted at 24 hours. Additionally, the association between brain tissue preserved and clinical outcome at 90 days was investigated. Results: From the 447 patients (252 [56.4%] male; median [IQR] age, 77.0 [68.0-84.0] years) included in this secondary analysis, 226 received EVT plus BMT and 221 received BMT alone. Median (IQR) time of the follow-up imaging was 22.9 (19.2-25.5) hours. Median (IQR) Time to maximum less than 6 seconds (Tmax6) volume was 34.0 (20.0-50.0) mL. Median follow-up infarct volume was 7.0 (1.0-22.9) mL. The median (IQR) change in absolute volume in the EVT plus BMT group was 23.6 (5.7-38.9) mL and 14.8 (0-30.3) mL in the BMT group. Median (IQR) change in Vrel was 0.8 (0.2-1.0) in the EVT plus BMT group and 0.6 (0-0.9) in the BMT group. Odds for reaching a change in Vrel of 0.8 or greater were higher in the EVT plus BMT group compared with BMT (adjusted odds ratio [aOR], 1.6; 95% CI, 1.1-2.3) and with successful reperfusion compared with no successful reperfusion (aOR, 2.5; 95% CI, 1.3-4.8). Patients with a change in Vrel of 0.8 or greater had a better clinical outcome at 90 days. Conclusions and Relevance: In this post hoc analysis of the DISTAL trial data, EVT plus BMT was associated with a higher likelihood of achieving a good imaging outcome compared with BMT alone. A good imaging outcome was associated with a better clinical outcome in both treatment groups.