Efficacy of exercise-based cardiac rehabilitation post–myocardial infarction: A systematic review and meta-analysis of randomized controlled trials

Background Exercise-based cardiac rehabilitation (CR) remains an underused tool for secondary prevention post–myocardial infarction (MI). In part, this arises from uncertainty regarding the efficacy of CR, particularly with respect to reinfarction, where previous studies have failed to show consistent benefit. We therefore undertook a meta-analysis of randomized controlled trials (RCTs) to (1) estimate the effect of CR on cardiovascular outcomes and (2) examine the effect of CR program characteristics on the magnitude of CR benefits. Methods We systematically searched MEDLINE as well as relevant bibliographies to identify all English-language RCTs examining the effects of exercise-based CR among post-MI patients. Data were aggregated using random-effects models. Stratified analyses were conducted to examine the impact of RCT-level characteristics on treatment benefits. Results We identified 34 RCTs (N = 6,111). Overall, patients randomized to exercise-based CR had a lower risk of reinfarction (odds ratio [OR] 0.53, 95% CI 0.38-0.76), cardiac mortality (OR 0.64, 95% CI 0.46-0.88), and all-cause mortality (OR 0.74, 95% CI 0.58-0.95). In stratified analyses, treatment effects were consistent regardless of study periods, duration of CR, or time beyond the active intervention. Exercise-based CR had favorable effects on cardiovascular risk factors, including smoking, blood pressure, body weight, and lipid profile. Conclusions Exercise-based CR is associated with reductions in mortality and reinfarction post-MI. Our secondary analyses suggest that even shorter CR programs may translate into improved long-term outcomes, although these results need to be confirmed in an RCT.