Coronary heart disease (CHD) includes a group of diseases like angina and myocardial infarction that are caused by the narrowing of coronary-artery walls by atheromatous plaques. Epidemiologic studies show that CHD is the most common cause of death globally, leading to one-third of all deaths. Currently, the mortality rate in the UK and in other high-income countries is decreasing due to better control over blood pressure and cholesterol levels, and to the prompt use of thrombolysis and stents in acute coronary syndromes. Thus, an increasing number of people live with CHD and may need support to manage their symptoms and prognosis.

In this scenario, cardiac rehabilitation (CR) by its definition aims to favorably influence the underlying cause of cardiovascular disease in order to provide the best possible conditions for the patients to preserve or to resume their optimal functioning in their community. Cardiac rehabilitation comprises many interventions such as exercise, risk-factor and behavioural modification, and psychological support. Modern cardiac societies strongly recommend (Class I recommendation) CR as the standard of care for patients who have suffered an acute cardiac event. Exercise training has been demonstrated to improve myocardial oxygen demand, endothelial function, autonomic tone, coagulation, and inflammatory markers and to promote angiogenesis.

This review investigated whether exercise-based cardiac rehabilitation compared to no exercise was effective in reducing mortality and morbidity as well as in improving health-related quality of life (HRQoL) in people with CHD.

This review is important for

People who have had an acute myocardial infarction, heart failure, and coronary revascularization; their loved ones/caregivers; health professionals caring for this population; general practitioners; researchers; and policymakers.

In particular, further evidence is needed from people who have difficulty accessing services such as women, elderly people, and ethnic minorities, and more data are needed on HRQoL and cost-effectiveness. 

Outcomes of this review

This is an update of Cochrane Systematic Reviews (CSRs) published in 2000, 2011, and 2015. The outcomes analyzed were mortality (either cardiovascular or from other causes), myocardial infarction (MI) events and revascularizations, hospitalization (either cardiovascular or from other causes), quality of life measures, and cost-effectiveness.

The CSR included a total of 85 trials published and/or registered up to June 2021, with 23,430 adult participants with CHD. This latest update identified 22 new trials with 7,795 participants.

Results show that at six-to-12 months, exercise-based CR probably slightly reduces all-cause mortality and significantly reduces MI events and all-cause hospitalization. Exercise-based CR probably makes little to no difference in the risk of cardiovascular mortality or revascularization risk through percutaneous coronary intervention (PCI), and it improves vascularization risk through coronary artery bypass graft (CABG). It is uncertain whether exercise-based CR improves cardiovascular hospitalization.

CR may lead to little or no difference in all-cause mortality, MI, PCI, CABG, and all-cause hospitalization at medium-term follow-up, whereas it showed a large reduction in cardiovascular mortality. It is uncertain whether CR improves the risk of cardiovascular hospitalization. Somewhat similarly, CR may result in a large reduction in cardiovascular mortality and MI events and little or no difference in all-cause mortality in the long term. It is uncertain whether CR improves revascularization risk through CABG and PCI in the long term. The intervention slightly improves HRQoL at 12 months follow-up; on the other hand, the intervention showed a potentially cost-effective gain in quality-adjusted life years (QALYs).

These results must be interpreted with caution because (i) most trials included predominantly male patients who had MI. However, with the new update to this Cochrane review, more women were included as well as studies conducted in lower-income countries, thus increasing the validity and generalizability of the results. Before the current update, there was a (ii) lack of adequate reporting of randomization and blinding, which was also improved in the newly included trials. (iii) Imprecision and publication bias affected the overall quality of the evidence for hospitalization from all causes and MI; on the other hand, (iv) heterogeneity affected cardiovascular hospitalization and HRQoL outcomes. (v) Shorter-term follow-up studies with small sample sizes led to a small number of reported events such as death and hospitalization. (vi) In some cases, the cause of death and individual adverse events were not reported, leading to apparently paradoxical findings like reduced all-cause mortality but not cardiovascular mortality in the short term. (vii) Poor and inconsistent reporting of adherence to exercise programs made it impossible to determine the actual amount of exercise that participants performed.

Author’s conclusion of the review

People with CHD who receive exercise-based CR may at 12 months have a reduced risk of MI, a likely small reduction in all-cause mortality, and a large reduction in all-cause hospitalization. Furthermore, there may be a reduction in healthcare costs and an improved quality of life. Over longer-term follow-up, benefits may include a reduction in cardiovascular mortality and MI. Trials from lower-income countries and those including a larger female population have improved the generalizability of the results, although people with angina pectoris, higher-risk CHD, and major comorbidities are still underrepresented. Thus, the applicability of the results in these cases remains a question of clinical judgement. The cost-effectiveness of the intervention remains uncertain; therefore, it would be rational to use cost considerations to determine CR practice.

Future recommendations

The authors recommended that well-designed, adequately reported randomized controlled trials are needed, particularly (a) to report mortality and hospital admissions causes, (b) to include validated quality of life measures, especially over longer-term follow-up, and (c) to determine the costs and cost-effectiveness of the intervention. (d) Moreover, high-risk populations and those with major comorbidities should be more represented in future trials. (e) Further trials should provide more details on the presentation, diagnoses, and interventions received by people with CHD, so as to allow a better stratification.

by Robin Kuruvila Sentinella