BACKGROUND: The burden of cardiovascular disease world-wide is one of great concern to patients and health care agencies alike. Circulatory diseases, including myocardial infarction (MI) and stroke, kill more people than any other disease. Cardiac rehabilitation aims to restore patients who have suffered myocardial infarction to optimal health through exercise only based rehabilitation or comprehensive cardiac rehabilitation (eg. smoking cessation advice, diet and counselling as well as exercise). Data from two published and widely cited meta-analyses (Oldridge 1988, O'Connor 1989) of over 4,000 patients each have demonstrated that patients randomised to exercise-based cardiac rehabilitation after MI have a statistically significant reduction in all-cause and cardiac mortality of about 20 to 25% compared to patients receiving conventional care. However, the trials included were small and often of poor methodological quality. Incomplete literature review methods may have resulted in publication bias thereby resulting in an over-estimate of the benefit of cardiac rehabilitation. The randomised controlled trials used in the reviews have focused almost exclusively on low-risk, middle-aged males post MI, thereby excluding women and the elderly. OBJECTIVES: To determine the effectiveness of exercise only rehabilitation and exercise in addition to other rehabilitation interventions (termed comprehensive cardiac rehabilitation) compared with usual care on the mortality, morbidity, health-related quality of life (HRQoL) and modifiable cardiac risk factors of patients with coronary heart disease. SEARCH STRATEGY: Electronic databases were searched for randomised controlled trials, using standardised trial filters, from the earliest date available to December 31st 1998. SELECTION CRITERIA: Men and women of all ages, in both hospital-based and community-based settings, who have had myocardial infarction, coronary artery bypass graft or percutaneous transluminal coronary angioplasty, or who have angina pectoris or coronary artery disease defined by angiography have been included. Studies involving participants following heart transplant, heart valve surgery or heart failure have been excluded. Follow up periods of less than 6 months were excluded. DATA COLLECTION AND ANALYSIS: Studies were selected independently by two reviewers, and data extracted independently. Authors were contacted where possible to obtain missing information. MAIN RESULTS: The current systematic review has allowed analysis of an increased number of patients from approximately 4500 in the earlier meta-analyses to 7683 (2582 in exercise only and 5101 in the comprehensive cardiac rehabilitation group). The quality of reporting overall was poor, with generally high losses to follow up. The pooled effect estimate for total mortality for the exercise only intervention shows a 27% reduction in all cause mortality (random effects model OR 0.73 (0.54, 0.98)). Similarly, comprehensive cardiac rehabilitation reduced all cause mortality compared to usual care, but to a lesser degree (OR 0.87 (0.71, 1.05)). Total cardiac mortality was reduced by 31% (random effects model OR 0.69 (0.51, 0.94)) and 26% (random effects model OR 0.74 (0.57, 0.96)) in the exercise only and comprehensive cardiac rehabilitation intervention groups respectively when compared to usual care. Neither intervention had any effect on the ocurrence of non-fatal myocardial infarction. There was a significant net reduction in total cholesterol in the comprehensive cardiac rehabilitation group (pooled WMD random effects model -0.57 mmol/l (-0.83, -0.31)), but not the exercise only rehabilitation group. Similarly, LDL was significantly reduced in the comprehensive cardiac rehabilitation group (pooled WMD random effects model -0.51 mmol/l (-0.82, -0.19). The effect of exercise only rehabilitation or comprehensive cardiac rehabilitation interventions on revascularisation rates, blood pressure or smoking behaviour could not be determined by this meta-analysis due to the small number of trials reporting these outcomes and heterogeneity between trials. It was not possible to combine the data from studies reporting HRQoL as an outcome. Eighteen different instruments were used to assess HRQoL in the 11 studies reporting it as an outcome. The data are presented qualitatively, only one trial reporting significant improvements with the intervention. REVIEWER'S CONCLUSIONS: Exercise-based cardiac rehabilitation appears to be effective in reducing cardiac deaths but the evidence base is weakened by poor quality trials. It is not clear from this review whether exercise only or a comprehensive cardiac rehabilitation intervention is more beneficial. The population studied in this review is still predominately male, middle aged and low risk. Identification of the ethnic origin of the participants was seldom reported.
