Bariatric Surgery and the Risk of New-Onset Atrial Fibrillation in Swedish Obese Subjects

BACKGROUND: Obesity is a risk factor for atrial fibrillation, which in turn is associated with stroke, heart failure, and increased all-cause mortality. OBJECTIVES: The authors investigated whether weight loss through bariatric surgery may reduce the risk of new-onset atrial fibrillation. METHODS: SOS (Swedish Obese Subjects) is a prospective matched cohort study conducted at 25 surgical departments and 480 primary healthcare centers in Sweden. The cohort was recruited between 1987 and 2001. Among 4,021 obese individuals with sinus rhythm and no history of atrial fibrillation, 2,000 underwent bariatric surgery (surgery group), and 2,021 matched obese control subjects received usual care (control group). The outcome, first-time atrial fibrillation, was ascertained by crosschecking the SOS database with the Swedish National Patient Register on inpatient and outpatient diagnosis codes. RESULTS: During a median follow-up of 19 years, first time atrial fibrillation occurred in 247 patients (12.4%) in the surgical group, and in 340 (16.8%) control subjects. The risk of developing atrial fibrillation was 29% lower in the surgery group versus the control group (hazard ratio: 0.71; 95% confidence interval: 0.60 to 0.83; p < 0.001). Younger individuals benefited more from surgical intervention than those who were older (p value for interaction 0.001). Also, those with a high diastolic blood pressure benefitted more from surgery than did those with a low diastolic blood pressure (p for interaction = 0.028). CONCLUSIONS: Compared with usual care, weight loss through bariatric surgery reduced the risk of atrial fibrillation among persons being treated for severe obesity. The risk reduction was more apparent in younger people and in those with higher blood pressure.