Risk of recurrent ischemic stroke after non-cardioembolic ischemic stroke in England and Denmark

BACKGROUND: Recurrent ischemic stroke (IS) can occur following a non-cardioembolic IS (NCIS), despite following secondary prevention guidelines. We quantified recurrent IS risk following discharge from first-ever NCIS in clinical practice. METHODS: Adult patients with first-ever NCIS were identified in England (January 2012-February 2020) and Denmark (January 2012-December 2021) and followed through March 2021 (England) and August 2022 (Denmark). Primary outcome was recurrent IS (incidence rates [IRs] per 100 person years at 12 months and over total follow-up). Cumulative hazard per 100 person years with 95% confidence intervals (CIs) was estimated. Stroke severity at index and recurrent IS were compared in Danish patients. RESULTS: Overall, 52,419 English and 62,501 Danish patients were included (respective mean follow-ups: 3.0 and 3.9 years). Recurrent IS events totaled 5857 in England, 9489 in Denmark. IRs/100 person years were similar (England: 3.74 [95% CI 3.64-3.84]; Denmark: 3.87 [95% CI 3.79-3.95]), and highest in the first year (England: 7.39 [95% CI 7.14-7.65]; Denmark: 7.96 [95% CI 7.73-8.20]). Five-year cumulative hazard of recurrent IS was 16.53 (95% CI 16.06-17.01) in England, 18.05 (95% CI 17.64-18.47) in Denmark. Among Danish cases with severity data (n = 5540), versus index strokes, recurrent IS events were more often moderate (13.84% vs 19.01%) or severe (3.57% vs 7.92%). CONCLUSIONS: Recurrent IS after NCIS was highest in the first year and remained substantial over 5 years. In Denmark, recurrent IS severity was worse than index events. These findings underscore unmet needs for improved secondary stroke prevention.