Exercise Training in Patients With Heart Failure and AF
Does atrial fibrillation (AF) impact the efficacy of aerobic exercise in heart failure (HF), and to what degree does exercise training in HF vary according to AF status?
HF-ACTION (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training) study investigators randomized 2,331 ambulatory HF patients (New York Heart Association class II-IV) with ejection fraction ≤35% to exercise training or usual care. Clinical characteristics and outcomes (mortality/hospitalization) were assessed by baseline AF status (past history of AF or AF on baseline electrocardiogram vs. no AF) using adjusted Cox models and by exploring an interaction with exercise training. An assessment was conducted of post-randomization AF events diagnosed via hospitalizations for AF and reports of serious arrhythmia caused by AF.
Of 2,292 patients with baseline rhythm data, 382 (17%) had AF, 1,602 (70%) had sinus rhythm, and 308 (13%) had “other” rhythm. Patients with AF were older and had lower peak oxygen consumption. Over a median follow-up of 2.6 years, AF was associated with a 24% per year higher rate of mortality/hospitalization (hazard ratio [HR], 1.53; p < 0.001) in unadjusted analysis; this did not remain significant after adjustment (HR, 1.15; p = 0.09). There was no significant difference in AF event rates by randomized treatment assignment in the overall population or by baseline AF status (all p > 0.1). There was no interaction between AF and exercise training on measures of functional status or clinical outcomes (all p > 0.1).
AF in patients with chronic HF (CHF) was associated with older age, reduced exercise capacity at baseline, and a higher overall rate of clinical events, but not a differential response to exercise training for clinical outcomes or changes in exercise capacity. There is evidence that fitness is inversely related to AF and recurrence. And in the entire cohort in the HF-ACTION trial, the volume of exercise over time, ranging from 3 to 7 MET-hours/week, was associated with a 30% reduction in cardiovascular mortality and HF hospitalizations. It is not just the 12-week/36 sessions that provides the long-term benefit.
CHF is an approved indication for cardiac rehabilitation (CR) based on HF-ACTION results, which demonstrated improved quality of life and exercise capacity, and reduced all-cause mortality and hospitalizations. It included 36 sessions of CR in 12 weeks with continuation of home exercise, with the goals of 90 minutes per week for the first 3 months, followed by 120 minutes per week thereafter.
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