Risk of stroke and intracranial hemorrhage in 9727 Chinese with atrial fibrillation in Hong Kong

Background: Current risk schemes to predict ischemic stroke and intracranial hemorrhage (ICH) in atrial fibrillation (AF) are derived primarily using a Caucasian population.

Objective: The purpose of this study was to describe the risk of ischemic stroke and ICH in a large contemporary "real world" cohort of Chinese AF patients in Hong Kong with detailed long-term follow-up.

Methods: This observational study used a hospital-based cohort of Chinese patients with nonvalvular AF.

Results: Among 9727 patients with nonvalvular AF (age 76.9 ± 12.5 years, 52.1% female), 3881 patients (39.9%) did not receive antithrombotic therapy, 3934 patients (40.4%) were taking aspirin, and 1912 (19.7%) were taking warfarin. After mean follow-up of 3.19 years, 847 patients (21.8%) without antithrombotic therapy developed ischemic strokes (annual risk 9.28%, 95% confidence interval [CI] 8.89%-9.70%). There was a progressively increase in annual risk of ischemic stroke with increasing CHADS2 and CHA2DS2VASc scores. The c-statistics revealed that CHA2DS2-VASc scores (0.525, 95% CI 0.509-0.541, P = .017) was better than CHADS2 scores (0.506, 95% CI 0.490-0.522, P = .584) in predicting ischemic stroke. Use of aspirin and of warfarin were associated with reduced annual risk of ischemic stroke by 18.7% and 52.7%, respectively (P <.05). The annual incidence of ICH in patients taking aspirin and warfarin was 0.77% per year and 0.80% per year, respectively. The adjusted net clinical benefit favored warfarin over aspirin or no therapy for almost all Chinese AF patients CHA2DS2-VASc score ≥1.

Conclusion: Chinese AF patients are at high risk for ischemic stroke. Analysis of the net clinical benefit favors the use of warfarin over aspirin or no therapy for stroke prevention in a broad range of Chinese AF patients.