Gender Affects Exercise Tolerance in Atrial Fibrillation

Although exercise has many cardiovascular benefits, including favorable vascular and metabolic changes, its impact on arrhythmias is less well understood. In particular, some studies have found a protective effect on atrial fibrillation (AF) whereas others have shown a possible increase in risk of AF with vigorous activity, which could result in electrical remodeling in the left atrium.

A recent meta-analysis presented at the American College of Cardiology Scientific Sessions 2015,¹ included 12 prospective observational studies (N=372,682) and reported some gender differences in the impact of exercise on AF. In the men (mean age, 56 years), vigorous exercise increased the hazard for AF 1.7 times (95% CI, 1.4-2.05) whereas moderate exercise was associated with an approximate 10% lower incidence of AF (HR=0.81; 95% CI, 0.34-0.96).  In women (mean age, 61 years), both moderate- and high-intensity exercise lowered the incidence of AF to HR=0.76 (95% CI, 0.21-0.82) and HR=0.85 (95% CI, 0.43-0.94), respectively.

There may be a hormonal influence on the risk of developing AF. Results of another observational study of ≈18,000 middle-aged women, presented at the Heart Rhythm Scientific Sessions 2015,² found that in women who underwent menopause before age 44 years, there was a 17% lower incidence of AF. However, there may be a high risk of confounding in this study related to medical comorbidities among participants and specific reasons for premature menopause.

Based on these data, clinicians can safely issue a prescription to male and female patients with AF to engage in moderate-intensity exercise. However, vigorous exercise should carry a warning. Although these results are observational in nature and therefore may be associative rather than causative, the large sample size and dramatic hazard ratios do provide some pause for high-intensity sports in those with AF.

References:

• Mohanty S, Mohanty P, Trivedi C, et al. Meta-analysis on association of different intensities of physical activity with risk of atrial fibrillation. J Am Coll Cardiol. 2015;65(10_S). doi: 10.1016/S0735-1097(15)60373-4.
• Jorge Wong, MD, postdoctoral fellow, Brigham and Women's Hospital, Boston; Anne Gillis, MD, professor, medicine, University of Calgary, Alberta, Canada; May 15, 2015, presentation, Heart Rhythm Society annual meeting, Boston.