Incident atrial fibrillation: Impact of obstructive sleep apnea and obesity

In the United States, the major clinical risk factors for atrial fibrillation (AF) include age, diabetes, hypertension, heart failure, and coronary artery disease. Recently, long-term follow-up data of more than 5,000 subjects in the Framingham Heart Study and nearly 48,000 subjects in the Danish Diet, Cancer, and Health Study showed that AF also is predicted by obesity, and this association is independent of other clinical characteristics. However, the mechanisms by which obesity leads to AF are unknown. This is an important question given the magnitude of both the obesity and AF epidemics. Obstructive sleep apnea (OSA) is highly prevalent in obese individuals, and it is estimated that more than 25 million US adults have OSA. We have previously shown in a cross-sectional analysis that OSA is strongly associated with AF, independent of age, gender, hypertension, heart failure, and obesity (Slide 1). It is estimated that about one-half of patients with medically complicated AF and about one-third of patients with lone AF have OSA. However, no study yet has identified the risk of incident AF attributable to OSA during long-term follow-up. We report in the Journal of the American College of Cardiology a historical cohort study that included 3,542 consecutive adult residents of our county who underwent their first diagnostic polysomnography between 1987 and 2003. Individuals with AF or a previous history of AF were excluded. Those enrolled in our study were followed up until death or last follow-up for the occurrence of incident AF or flutter, which was confirmed by an electrocardiogram. After an average of 5 years of follow-up (maximum 15 years), the cumulative frequency of AF was 14% and this was predicted by several well-established risk factors, such as male sex, age, hypertension, coronary artery disease, and heart failure. We also found that body mass index, OSA, the apnea-hypopnea index, and several oxygen saturation parameters strongly predicted AF (Slide 2). In multivariate regression models, age, male sex, coronary artery disease, body mass index (per 1 kg/m²; hazard ratio [HR], 1.07; 95% confidence interval [CI], 1.05-1.10; p < 0.001), and a decrease in nocturnal oxygen saturation (per 0.5 unit change in the log; HR, 3.29; 95% CI, 1.35-8.04; p = 0.009) were independent predictors of incident AE For subjects ≥65 years old, only heart failure independently predicted incident AF (HR, 7.68; 95% CI, 4.32-13.66; p < 0.001).