Abstract 3162: Physical Activity and the Risk of Incident Atrial Fibrillation in Women
Physical activity (PA) is well known to reduce the risk of cardiovascular disease. We hypothesized that regular PA, possibly acting through reductions in blood pressure and body mass index (BMI), would reduce the risk of incident atrial fibrillation (AF) in women. We prospectively followed 34,285 women who reported their leisure-time PA levels and AF. We estimated energy expenditure in metabolic equivalent (MET)-hrs/wk, and validated self-reported AF with medical records. The mean (SD) age of the 34,285 participants was 54.6 (7.0) years and the mean was BMI 26.0 (5.0) kg/m2. The proportion with hypertension at baseline was 25.3%, and the median (IQR) PA was 8.4 (2.8, 20.4) MET-hrs/wk. After a median of 12.4 years of observation, 648 women developed AF. Among the 648 cases of AF, 428 were paroxysmal, 110 persistent, 86 chronic and 24 could not be categorized. In age adjusted proportional hazards models, increasing quintiles of PA associated with a reduced risk of AF (Table⇓). This association was not substantially different after adjustment for hypertension, but was attenuated and non-significant after adjustment for BMI. Women not meeting current PA recommendations (<7.5 MET-hrs/wk) had a non-statistically significant increased risk for AF (age-adjusted hazard ratio (HR) 1.16 (95% confidence interval 0.99 –1.35), P=0.06). The most sedentary women (<2 MET-hrs/wk) did have a significantly increased risk (age-adjusted HR 1.27 (1.06 –1.52), P<0.01) compared to those more active. After adjustment for hypertension this relationship was not substantially different (HR 1.22 (1.02–1.46), P=0.03) but was attenuated and no longer significant after adjustment for BMI (HR 1.10 (0.92–1.33), P=0.3). In age adjusted analyses, a sedentary lifestyle was associated with a modestly increased risk of AF. This relationship appears to be mediated predominantly by body mass index rather than by blood pressure.