Abstract: Seven studies (581 participants) met our inclusion criteria. Trials had an intervention length of 6 weeks to 12 months and follow-up length of 6 to 12 months. The comparison group in all trials was usual care (without any form of structured exercise training or advice) or a no-exercise comparator. The mean age of participants within the trials ranged from 50 to 66 years, the majority of participants being male (range: 74% to 100%). In terms of risk of bias, the majority of studies were unclear about their generation of the randomisation sequence and concealment processes. One study was at high risk of detection bias as it did not blind its participants or outcome assessors, and two studies had a high risk of attrition bias due to the numbers of participants lost to follow-up. Two trials were at high risk of outcome reporting bias. Given the high risk of bias, small number of trials and participants, and concerns about applicability, we downgraded our assessments of the quality of the evidence using the GRADE tool. Due to the very low-quality of the evidence base, we are uncertain about the effect of exercise-based CR on all-cause mortality (risk ratio (RR) 1.01, 95% confidence interval (CI) 0.18 to 5.67; 195 participants; 3 studies; very low-quality evidence), acute myocardial infarction (RR 0.33, 95% CI 0.07 to 1.63; 254 participants; 3 studies; very low-quality evidence) and cardiovascular-related hospital admissions (RR 0.14, 95% CI 0.02 to 1.1; 101 participants; 1 study; very low-quality evidence). We found low-quality evidence that exercise-based CR may result in a small improvement in exercise capacity compared to control (standardised mean difference (SMD) 0.45, 95% CI 0.20 to 0.70; 267 participants; 5 studies, low-quality evidence). We were unable to draw conclusions about the impact of exercise-based CR on quality of life (angina frequency and emotional health-related quality-of-life score) and CR-related adverse events (e.g. skeletomuscular injury, cardiac arrhythmia), due to the very low quality of evidence. No data were reported on return to work. Due to the small number of trials and their small size, potential risk of bias and concerns about imprecision and lack of applicability, we are uncertain of the effects of exercise-based CR compared to control on mortality, morbidity, cardiovascular hospital admissions, adverse events, return to work and health-related quality of life in people with stable angina. Low-quality evidence indicates that exercise-based CR may result in a small increase in exercise capacity compared to usual care. High-quality, well-reported randomised trials are needed to assess the benefits and harms of exercise-based CR for adults with stable angina. Such trials need to collect patient-relevant outcomes, including clinical events and health-related quality of life. They should also assess cost-effectiveness, and recruit participants that are reflective of the real-world population of people with angina.

Plain-language summary: The evidence is current to 2 October 2017. We included seven studies that randomly allocated a total of 581 participants with stable angina to either receive cardiac rehabilitation or no exercise control. We identified that there are no ongoing randomised studies. The average age of participants ranged from 50 to 66 years. The majority of people recruited were middle-aged men. Most studies were carried out in European countries and one study in India. Cardiac rehabilitation was most commonly delivered in a combined setting of home and centre or hospital. The length of the cardiac rehabilitation programmes ranged from six weeks to one year. There is insufficient evidence to assess the impact of exercise-based cardiac rehabilitation on the outcomes that matter most to patients: risks of death, heart attack, or future cardiac operation and quality of life. There may be a small improvement in physical fitness following exercise-based cardiac rehabilitation compared to usual treatment. There was no evidence about returning to work. Due to the poor reporting, high risk of bias and small number of trials and participants included in this review, our assessment of the quality of the evidence ranged from low to very low across outcomes. For low-quality evidence our confidence in the result is limited, and for very low-quality evidence we have very little confidence in the result. We need more high-quality studies in more representative populations of people with stable angina. These studies should collect outcomes of relevance to patients and healthcare decision-makers. Then we will be able to better assess the impact of exercise-based cardiac rehabilitation.