Meta-analysis on association of different intensities of physical activity with risk of atrial fibrillation

Background: Regular physical activity (PA) is well known to reduce the risk of many cardiovascular diseases. However, the impact of PA on the risk of atrial fibrillation (AF) appears to be more complex. While some studies have reported the protective effect of moderate as well as vigorous- intensity PA, others have found increase in the risk of AF with high-intensity exercise. This study aims to systematically evaluate and summarize the evidence regarding association of different levels of PA and risk of AF. Methods: Pubmed, Medline, EMBASE and other databases were searched up to August 2014 and reference lists of selected articles for trials that reported relation between physical activity and incidence of atrial fibrillation. Studies were included if they evaluated the association between incident AF and the level of exercise in multivariate models. A random effect inverse variance weighted meta-analysis was performed, by entering the logarithm of the adjusted hazard ratio (HR). Data are expressed as HR with 95% confidence interval (CI). results: Twelve prospective observational studies with 379,682 patients (males, 56.4±8.88 years, females 61.03±8.47) were included. Two of the 12 studies involved only female subjects, two studies reported both male and female, and the remaining 8 studies included male subjects only. As revealed in the adjusted pooled analysis, among men, vigorous exercise was associated with increased risk of AF (HR 1.73, 95% CI 1.4 to 2.05), whereas, moderate exercise lowered AF incidence (HR 0.81, 95% CI 0.34 to 0.96). In case of women both moderate (HR 0.76, 95% CI 0.21 to 0.82) and high intensity PA (HR 0.85, 95% CI 0.43 to 0.94) was associated with reduced risk of AF. Conclusion: Vigorous exercise is associated with increased risk while moderate physical activity lowers the incidence of atrial fibrillation in men. However, both level of physical activity appear to be beneficial in women by modestly reducing the risk of this arrhythmia. This interesting relationship between level of physical activity and atrial fibrillation needs further evaluation in future studies with age- and exercise-intensity matched population from both genders.