Higher early recurrence risk and potential benefit of dual antiplatelet therapy for minor stroke with watershed infarction: subgroup analysis of CHANCE

Background and purpose The aim was to explore the risk of early stroke recurrence within 3 months after watershed infarction and to investigate whether early dual antiplatelet therapy is more effective in decreasing such risk. Methods Patients enrolled in the Clopidogrel in High-risk Patients with Acute Non-disabling Cerebrovascular Events (CHANCE) trial and who had acute infarction on diffusion-weighted imaging were included in this subgroup analysis. All magnetic resonance images were read centrally by two neurologists who were blinded to the patients' baseline and outcome information. The primary outcome was any stroke recurrence within 3 months. The hazard ratios were adjusted by known predictors of stroke recurrence. Results Of the 1089 patients with magnetic resonance imaging data enrolled in CHANCE, 834 (76.58%) patients had acute infarcts on diffusion-weighted imaging. The median and range of duration from randomization to stroke recurrence was 1.5 (1-6) days. Patients with watershed infarction had higher risk of stroke recurrence than those without (17.20% vs. 6.34%) within the first week after initial stroke; the hazard ratio (95% confidence interval) was 2.799 (1.536-5.101) adjusted by age, sex, smoking, body mass index, medical history, time to randomization, open-label aspirin dose at first day, single or dual antiplatelet therapy, National Institutes of Health Stroke Scale score at randomization, in-hospital treatment and white matter lesions, P < 0.001. There was no interaction between antiplatelet therapy and the presence of watershed infarction (P = 0.544). Conclusions Minor stroke with watershed infarction has high recurrent risk in the first week. Dual antiplatelet therapy may be safely implemented, yet watershed infarction mechanisms of hypoperfusion and emboli may not be addressed.