Resting Heart Rate and Physical Activity as Risk Factors for Lone Atrial Fibrillation: A Prospective Study of 309,540 Men and Women
Do physical activity and low resting heart rate (HR) predispose to lone atrial fibrillation (AF)?
The subjects of this study were 147,462 men and 162,078 women, ages 40-45 years (mean age, 41.4 years), who underwent a health screening examination in Norway in 1985-1999. Activity level was self-reported. A national database was used to identify the primary study outcome: a prescription for flecainide or sotalol in 2005-2009. This was used as a surrogate for AF.
A total of 575 men (0.4%) and 288 women (0.2%) received ≥1 prescription for flecainide or sotalol during follow-up. Each 10 bpm reduction in resting HR was associated with a higher probability of receiving flecainide (29% higher in men and 12% higher in women). The probability of receiving a flecainide prescription increased significantly with greater physical activity in men, but not women.
The authors concluded that a lower resting HR increases the risk of drug-treated AF in men and women. They also concluded that in men, higher levels of physical activity increase the risk of AF.
The present study provides weak evidence that a lower HR and increased physical activity increase the risk of AF. The use of flecainide and sotalol prescriptions as a surrogate for AF assumes that all patients with AF are treated with these two drugs and that these drugs are not used to treat other arrhythmias. But many patients with AF are undiagnosed, untreated, treated with rate-control drugs, or treated with other agents such as amiodarone. Another major limitation is that HR and activity levels were assessed only once, and as many as 20 years before identification of the study endpoint.
Keywords: Outcome Assessment (Health Care), Risk, Follow-Up Studies, Norway, Motor Activity, Transcription Factors, Risk Factors, Heart Rate
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