Obesity has been shown to be associated with atrial enlargement and ventricular diastolic dysfunction, both of which are risk factors for atrial fibrillation (AF). However, the role of obesity as a risk factor for the development of AF is unknown. The study aims to evaluate the role of obesity as a risk factor for the development of AF.

The MEDLINE/ PUBMED and Cochrane databases were searched for studies in human subjects published in English language between 1966 and May 2007. Studies were included in our analyses if they were population-based cohort or postcardiac surgery cohort and investigated the incidence of AF in relation to the body mass index (BMI) categories.

Of the 468 articles identified, 16 studies that enrolled a total of 123249 individuals met the inclusion criteria. These 16 articles included 5 population-based cohort studies that enrolled 78602 adult individuals from the United States and 3 European countries and 11 postcardiac surgery studies that enrolled 44647 patients.

Based on the population-based cohort studies, obese individuals have an associated 49% increased risk of developing AF compared to nonobese individuals (relative risk 1.49, 95% CI 1.36-1.64). The risk of AF increased in parallel with greater BMI in this cohort. In contrast, in the postcardiac surgery studies, obese individuals do not have an associated increased risk of developing AF compared to nonobese individuals (relative risk 1.02, 95% CI 0.99-1.06).

Our findings demonstrate that obesity increased the risk of developing AF by 49% in the general population, and the risk escalated in parallel with increased BMI. Thus, AF evolves as yet another pathogenetic factor by which obesity may increase cardiovascular and cerebrovascular events.