Relation Between Volume of Exercise and Clinical Outcomes in Patients With Heart Failure

Background The HF-ACTION (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training) trial showed that among patients with heart failure (HF), regular exercise confers a modest reduction in the adjusted risk for all-cause mortality or hospitalization. Objective This study determined whether greater volumes of exercise were associated with greater reductions in clinical events. Methods Patients randomized to the exercise training arm of HF-ACTION who were event-free at 3 mo after randomization were included (n= 959). Median follow-up was 28.2 months. Clinical end points were all-cause mortality or hospitalization and cardiovascular mortality or HF hospitalization. Results A reverse J-shaped association was observed between exercise volume and adjusted clinical risk. Based on Cox regression, exercise volume was not a significant linear predictor but was a logarithmic predictor (p=0.03) for all-cause mortality or hospitalization. For cardiovascular mortality or HF hospitalization, exercise volume was a significant (p=0.001) linear and logarithmic predictor. Moderate exercise volumes of 3 to <5 and 5 to <7 MET-hr per week were associated with reductions in subsequent risk that exceeded 30%. Exercise volume was positively associated with the change in peak oxygen uptake at 3 months (r=0.10; p=0.005). Conclusions In patients with chronic systolic HF, volume of exercise is associated with the risk for clinical events, with only moderate levels (3–7 MET-hr per week) of exercise needed to observe a clinical benefit. Although further study is warranted to confirm the relationship between volume of exercise completed and clinical events, our findings support the use of regular exercise in the management of these patients. Clinical Trial Registry: http://clinicaltrials.gov/ct2/show/NCT00047437