A moderate amount of physical activity appears to reduce the risk of atrial fibrillation (AF) significantly in middle-aged and elderly women, according to a study published in Heart.

Information about physical activity was obtained from 36,513 women, aged 49-83 (median 60) years in the Swedish Mammography Cohort who had completed a questionnaire at study entry. Participants reported their time spent on leisure-time exercise and on walking or cycling throughout their lifetime (at study entry, and at 30 and 50 years of age).

Walking/cycling for transportation was considered to be low to moderate intensity physical activity, while leisure-time exercise was considered to be moderate to high intensity physical activity.

The authors used the Swedish National Inpatient Register to determine whether participants were diagnosed with AF. Results were adjusted for potential confounders.

Overall, 2,915 cases of AF were diagnosed during a median follow-up period of 12 years.

The risk of AF decreased with increasing levels of physical activity at study entry:

• Leisure-time exercise ≥ 4 hr/week compared with < 1 hr/week, RR 0.85 (95% CI: 0.75-0.95)

• Walking/cycling for ≥ 40 min/day compared with almost never walking or cycling, RR 0.81 (95% CI: 0.72-0.92).

AF is the most common arrhythmia that we encounter in primary care. It is associated with increased morbidity and mortality.

The association between exercise and AF is somewhat dichotomous and there may be a U-shaped relationship between the intensity of exercise and AF risk. In men, long-term regular intense sporting activity particularly of the endurance variety can increase the risk of developing AF. However, in older men moderate physical activity seems to decrease the risk.

This study addressed an area that is relatively light on evidence at present; the association between AF and exercise in middle-aged and elderly women.

This was a large prospective study with complete follow up. However, the authors acknowledge that it relied on self-reporting of physical activity and the intensity of exercise was not measured.

The authors concluded that moderate physical activity was sufficient to reduce risk of AF in middle-aged and older women significantly.

These findings provide further support for encouraging regular exercise in our patients.

Dr Peter Savill