Residual Risk of Recurrent Stroke Despite Anticoagulation in Patients With Atrial Fibrillation

Importance: Atrial fibrillation (AF) is a leading cause of stroke, and oral anticoagulants (OAC) reduce this risk. However, there are limited data on the residual risk of recurrent stroke in patients with AF. Objective: To determine the recurrent stroke risk in patients with AF by performing a systematic review and meta-analysis. Data Sources: Eligible studies were identified by searching Ovid MEDLINE and Embase from inception (Ovid: January 1946; Embase: January 1970) until January 2025. Study Selection: Eligible studies enrolled patients with prior ischemic stroke and AF, reported information on incidence of recurrent stroke, and had follow-up data for 1 or more years. Three reviewers independently screened abstracts and performed full-text reviews. Data Extraction and Synthesis: Data extraction was performed by 2 reviewers and independently verified by a third. Incidence rates were pooled using random-effects meta-analysis. Analysis was repeated in patients whose qualifying event occurred despite OAC. Study quality was assessed using the Quality In Prognosis Studies tool. Main Outcomes and Measures: The primary outcome was recurrent ischemic stroke. The secondary outcomes were any recurrent stroke (ischemic stroke or intra-cerebral hemorrhage [ICH]) and ICH during follow-up. Results: A total of 23 studies were identified, which included 78 733 patients and 140 307 years of follow-up. The median proportion of OAC use across studies was 92%. The pooled incidence of recurrent ischemic stroke was 3.75% per year (95% CI, 3.17%-4.33%). The risk was higher in noninterventional observational cohorts (4.20% per year; 95% CI, 3.41%-4.99%) compared with randomized clinical trials (2.26% per year; 95% CI, 1.96%-2.57%) (P value for interaction <.001). The risk of any recurrent stroke was 4.88% per year (95% CI, 3.87%-5.90%), and the risk of ICH was 0.58% per year (95% CI, 0.43%-0.73%). In patients with stroke despite OAC, the risk was 7.20% per year (95% CI, 5.05%-9.34%) for ischemic stroke, 8.96% per year (95% CI, 8.25%-9.67%) for any stroke, and 1.40% per year (95% CI, 0.40%-2.40%) for ICH. Conclusions and Relevance: In this systematic review and meta-analysis, even with modern prevention therapy, the residual recurrence risk after AF-related stroke is high, with an estimated 1 in 6 patients experiencing a recurrent ischemic stroke at 5 years. These data demonstrate an urgent need to improve our understanding of the biological processes responsible for recurrence, improve risk stratification, and develop new secondary prevention strategies after AF-related stroke.