BACKGROUND: Atrial fibrillation (AF) is a common arrhythmia shown to be a major independent risk factor for stroke. However, limited information is available on AF in Korea. We examined the incidence and risk factors of AF, and contribution of comorbidities to AF incidence using a nationwide cohort study.

METHODOLOGY/RESULTS: The National Health Insurance Service-National Sample Cohort (NHIS-NSC) database during 2002-2010 was searched for subjects diagnosed with AF. We excluded subjects who were less than 30 years or diagnosed with AF during the window period (2002-2004). During a six-year follow-up period, 3,517 subjects (1.7%) developed AF. The incidence rates in men and women aged 30-39 years were 0.82 and 0.55 per 1000 person-years, respectively; the incidence rates further increased with age to 13.09 and 11.54 per 1000 person-years in men and women aged≥80 years, respectively. The risk factors for incident AF were age, sex, body mass index (BMI), hypertension, ischemic heart disease (IHD) and heart failure. After adjusting for variables related to AF, the population attributable fractions (PAFs) for hypertension, IHD and heart failure were 16.6%, 8.2% and 5.3%, respectively.

CONCLUSION: Incidence of AF increased with age and was higher in men than in women. Risk of AF was significantly associated with hypertension, IHD and heart failure. Hypertension is a major contributor to AF. These findings suggest the importance of hypertension management in preventing AF.