• Linda Long, Lindsey Anderson, Alice M Dewhirst, Jingzhou He, Charlene Bridges, Manish Gandhi, and Rod S Taylor.
• Institute of Health Research, University of Exeter Medical School, Exeter, UK.
• Cochrane Db Syst Rev. 2018 Feb 2; 2: CD012786.

BackgroundA previous Cochrane review has shown that exercise-based cardiac rehabilitation (CR) can benefit myocardial infarction and post-revascularisation patients. However, the impact on stable angina remains unclear and guidance is inconsistent. Whilst recommended in the guidelines of American College of Cardiology/American Heart Association and the European Society of Cardiology, in the UK the National Institute for Health and Care Excellence (NICE) states that there is "no evidence to suggest that CR is clinically or cost-effective for managing stable angina".ObjectivesTo assess the effects of exercise-based CR compared to usual care for adults with stable angina.Search MethodsWe updated searches from the previous Cochrane review 'Exercise-based cardiac rehabilitation for patients with coronary heart disease' by searching the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, DARE, CINAHL and Web of Science on 2 October 2017. We searched two trials registers, and performed reference checking and forward-citation searching of all primary studies and review articles, to identify additional studies.Selection CriteriaWe included randomised controlled trials (RCTs) with a follow-up period of at least six months, which compared structured exercise-based CR with usual care for people with stable angina.Data Collection And AnalysisTwo review authors independently assessed the risk of bias and extracted data according to the Cochrane Handbook for Systematic Reviews of Interventions. Two review authors also independently assessed the quality of the evidence using GRADE principles and we presented this information in a 'Summary of findings' table.Main ResultsSeven 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.Authors' ConclusionsDue 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.

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