Abstract: We found six Cochrane systematic reviews and judged them to be of high methodological quality. They included 148 randomised controlled trials (RCTs) in 98,093 participants. Compared with usual care alone, the addition of exercise-based cardiac rehabilitation in low-risk people after myocardial infarction or percutaneous coronary intervention or with heart failure appeared to have no impact on mortality, but did reduce hospital admissions and improved health-related quality of life. Psychological- and education-based interventions alone appeared to have little or no impact on mortality or morbidity but may have improved health-related quality of life. Home- and centre-based programmes were equally effective in improving quality of life outcomes at similar healthcare costs. Selected interventions can increase the uptake of cardiac rehabilitation programmes whilst there is currently only weak evidence to support interventions that improve adherence to cardiac rehabilitation programmes. The quality of the primary RCTs in the included systematic reviews was variable, and limitations in the methodological quality of the RCTs led to downgrading of the quality of the evidence, which varied widely by review and by outcome. Exercise-based cardiac rehabilitation is an effective and safe therapy to be used in the management of clinically stable people following myocardial infarction or percutaneous coronary intervention or who have heart failure. Future RCTs of cardiac rehabilitation need to improve their reporting methods and reflect the real world practice better including the recruitment of higher risk people and consideration of contemporary models of cardiac rehabilitation delivery, and identify effective interventions for enhancing adherence to rehabilitation.

Plain-language summary: We searched for Cochrane reviews that analysed the data from randomised controlled trials (RCT; experiments that randomly allocate participants to one of two or more treatment groups), which looked at the effectiveness of CR in adults with heart disease and compared patient outcomes with a no-exercise control group. This overview summarised the findings from these reviews. We found six high-quality Cochrane reviews that included 148 RCTs in 98,093 people who primarily had experienced a heart attack, had undergone cardiac surgery or had chronic heart failure. The findings of this overview showed important benefits of CR participation that included a reduction in the risk of hospital admissions, as well as improvements in health-related quality of life compared with not undertaking rehabilitation. The quality of the RCTs in the included systematic reviews was variable, and limitations in their methodological quality led to downgrading of the quality of the evidence, which varied widely by review and outcome. We make the following recommendations for the future conduct and reporting of systematic reviews of CR. • The scope of CR reviews needs to reflect current guidelines that recommend that CR should be based on an individually prescribed programme of exercise training with appropriate co-interventions. • Future CR reviews need to explore the complexity of CR using appropriate approaches to explore the association between intervention characteristics and outcomes across trials. • Future Cochrane CR reviews need to standardise their methods and reporting.