Dual versus single antiplatelet therapy in patients with non-cardioembolic acute ischemic stroke and baseline MRI

Introduction: Dual antiplatelet therapy (DAPT) is superior to single antiplatelet therapy (SAPT) for secondary prevention after minor, non-cardioembolic stroke. We aimed to assess whether DAPT efficacy is modified by large artery atherosclerotic (LAA) etiology, and DAPT safety by stroke size on MRI.Patients and methods: Post hoc analysis of the Phase 2 PACIFIC-STROKE randomized clinical trial, which enrolled patients with non-cardioembolic stroke, all with baseline MRI and compared the Factor XIa inhibitor asundexian with placebo on a background of DAPT or SAPT. We compared patients treated with DAPT versus SAPT. The efficacy endpoint was the rate of recurrent ischemic stroke, the safety endpoint was major or clinically relevant non-major bleeding during follow-up.Results: 1590 patients were included, median NIHSS was 2 (interquartile range [IQR] 1-4), 40% received DAPT. Median follow-up was 11.5 months. The efficacy endpoint occurred in 4.4% and 4.8% in the DAPT group and SAPT group, respectively, with the strongest numerical benefit of DAPT over SAPT among patients with NIHSS <= 3 not treated by intravenous thrombolysis. LAA index stroke etiology did not modify DAPT treatment effect. The safety endpoint occurred more often in the DAPT than in the SAPT group (4.6% vs 2.7%), with the numerically lowest risk among patients with NIHSS <= 3 not treated by intravenous thrombolysis. Stroke size did not modify the effect of DAPT on the safety endpoint.Discussion and conclusion: We found no evidence of major treatment effect heterogeneity with DAPT compared with SAPT in patients with and without LAA or by stroke size on MR-DWI.