Body Mass Index Variability and Long-term Risk of New-Onset Atrial Fibrillation in the General Population: A Korean Nationwide Cohort Study

Objective: To assess the effects of body mass index (BMI) variability on the incidence of new-onset atrial fibrillation (AF), stroke, cardiovascular (CV) risk factors, and CV outcomes in a general Asian population. Patients and Methods: Data from the National Health Insurance Service–Health Screening cohort in Korea were used: 171,324 patients without AF were included, and BMI measurements occurred biennially from January 1, 2002, through December 31, 2009. Patient outcomes were followed through 2013. The BMI intraindividual variability between visits was measured. Results: During mean ± SD follow-up of 47.4±3.9 months, 1959 patients (1.1%) developed new-onset AF. Overweight or obesity (BMI ≥25) had a greater risk of new-onset AF compared with BMI of 20 to 22.5, with a hazard ratio (HR) of 1.24 (95% CI, 1.10-1.41; P<.001). In underweight or normal-weight participants (initial BMI <25), a 1-kg/m² increase of BMI variability increased the risk of new-onset AF, with an adjusted HR (aHR) of 1.13 (95% CI, 1.01-1.25; P=.02). Weight gain increased the risk of new-onset AF (aHR, 1.32; 95% CI, 1.01-1.71; P=.04) and myocardial infarction (aHR, 1.52; 95% CI, 1.06-2.18; P=.02) but not stroke. In this group, blood pressure, glucose level, and total cholesterol level were higher in individuals with the greatest BMI variability compared with those with stable BMI. Conclusion: In the underweight and normal-weight Asian population, BMI variability, especially weight gain, was related to increased risk of new-onset AF and myocardial infarction. Avoiding weight gain is important to improve CV outcomes.