EXERCISE CAPACITY AND ATRIAL FIBRILLATION RISK IN 459,592 HYPERTENSIVES: A COHORT STUDY

Abstract

Objective: To assess the association between exercise capacity and the risk of developing atrial fibrillation (AF) in hypertensive patients. Design and method: We identified 459,675 hypertensives (63 ± 8.6 years, females: 4.9%), free of AF, who completed a normal Bruce exercise treadmill test (ETT). We established 5 fitness categories (quartiles) based on age-specific peak metabolic equivalents (METs) achieved: Least-fit (4.5 ± 1.22 METs; n = 107,593); Low-fit (6.9 ± 1.07; n = 119,433); Moderate-fit (8.3 ± 1.19; n = 88,923); Fit (10.3 ± 0.89; n = 106,921), and High-fit (13.1 ± 1.55; n = 36,722). Hazard regression models were adjusted for age, BMI, smoking (33.5%), DM (43.6%), dyslipidemia (69.8%) and CKD (5.8%). Results: During a median follow-up of 9.8 ± 5.0 years, 42,639 (9.6%) developed AF (9.6 per 1000 person-years). EXCP was inversely related to AF incidence. The risk was 11% lower (HR:0.89, 95% CI, 0.88–0.90) for each 1-MET increase in exercise capacity. Compared to the Least-fit category (Referent), the HRs were 0.72 (95% CI, 0.71–0.74) for Low-fit individuals, 0.61 (95% CI, 0.60–0.63) for Moderate-fit, 0.52 (95% CI, 0.50–0.54) for Fit, and 0.45 (95% CI, 0.43–0.47) for High- fit individuals. Similar trends for those < 65 years & > 65 years of age. Conclusions: Our findings support that increased fitness offer a marked protection against AF. The association was inverse, independent, and graded. Significantly lower AF risk was evident in those with only modest increases in exercise capacity and declined by > 50% for individuals in the High-fit category. These findings counter previous suggestions that even moderate increases in physical activity, (recommended by guidelines), increase the risk of AF.