BACKGROUND Atrial fibrillation (AF) and stroke are common in hypertrophic cardiomyopathy (HCM). We aimed to determine the prevalence and incidence of AF and stroke in patients with HCM during a 10-year period.

METHODS Using the Korean National Health Insurance Services database, we identified patients diagnosed with HCM from the entire Korean population between 2005 and 2015. The annual prevalence and incidence of AF and stroke in HCM patients were estimated.

RESULTS The prevalence of AF in HCM patients has gradually increased to 1.6-fold from 13.4% in 2005 to 20.9% in 2015. The incidence of AF ranged from 4.1 to 5.5%, a similar trend was observed for each year in HCM patients. The prevalence of stroke in HCM patients was approximately 10%, while that in HCM patients with AF was about 20%. During 8741 person-years, AF-related stroke occurred in 257 subjects among 2309 HCM patients with new-onset AF. The overall incidence rate of AF-associated stroke was 2.94 per 100 person-years. In subgroup analysis, the incidence rate of AF-associated stroke was 1.49 per 100 person-years in the under 45 year-old group and 1.48 per 100 person-years in the group with CHA₂DS₂-VASc score of 0 or 1 point in HCM patients.

CONCLUSIONS The prevalence of AF in HCM patients gradually increased over 10 years. The annual risk of AF-associated stroke in HCM was over 1% even in younger patients and those with CHA₂DS₂-VASc score of 0 or 1 point, which provide evidence to support the prevention of stroke in HCM patients with AF.