- Click here for explanation of classification scheme.

To determine the effectiveness of exercise only or exercise as part of a comprehensive cardiac rehabilitation program on the mortality, morbidity, health-related quality of life (HRQoL) and modifiable cardiac risk factors of patients with coronary heart disease (CHD).

• Randomized controlled trials (RCTs) of exercise-based cardiac rehabilitation vs. conventional care with a follow-up period of greater than six months
• Men and women of all ages, in hospital or community settings, who have had one or more of the following:
  • Myocardial infarction (MI)
  • Coronary artery bypass graft (CABG)
  • Percutaneous transluminal coronary angioplasty (PTCA)
  • Angina pectoris or coronary artery disease defined by angiography.

 

Participants following heart transplants, heart valve surgery or heart failure.

• Earliest date available to December 31,1998. Amended in 2000 and 2003.
• Electronic databases searched:
  • Cardiovascular randomised controlled trials register at McMaster University
  • Central/CCTR
  • MEDLINE
  • EMBASE
  • CINAHL
  • AMED
  • BIDS ISI
  • SPORTSDISCUS (using appropriate RCT filters for MEDLINE and EMBASE)
• In addition, reference lists of retrieved articles have been examined for further trials, conference proceedings have been examined for unpublished and ongoing trials of cardiac rehabilitation and expert advice has been sought.

Types of Intervention

• Cardiac rehabilitation is defined for this review as inpatient, outpatient or community-based intervention that is applied to a cardiac patient population. The intervention must include some form of exercise training.
• The following comparisons have been made:
  • Exercise training alone and usual care vs. usual care alone (exercise only vs. usual care)
  • Exercise training in addition to psychosocial and/or educational interventions vs. usual care alone (comprehensive cardiac rehabilitation vs. usual care).

Types of Outcome Measures

• The principal outcome measures were:
  • All cause mortality
  • Cardiac mortality, further subdivided into deaths from MI, sudden cardiac deaths, deaths from cerebrovascular disease (CVD)
  • Non-fatal MI
  • Revascularization, CABG, PTCA
  • Non fatal CVD events
  • Health related quality of life (HRQoL)
• Secondary outcome measures:
  • Modifiable cardiac risk factors:
    • Smoking behavior
    • Blood pressure
    • Blood lipid levels.

Statistical Analysis

• Dicotomous outcomes for each study were expressed as odds ratios (OR) and 95% confidence intervals (CI) 
• Where standard deviations were not expressed in the source papers, allowance was made for within patient correlation from baseline to follow-up measurements by using the correlation coefficent between the two (Cochran Heart Group, 1992)
• A weighted mean difference (WMD) and 95% CI were calculated for each study
• Data from each study were pooled, as appropriate using a fixed effect model, except where substantial heterogeneity existed according to the Z statistic, and a random effects model was used. 

 

• N: Over 4,000 citations were retrieved from the search of databases
  • 300 references were retrieved for possible inclusion
  • Thirty-two trials were included with 8,440 individuals (2,845 in exercise only and 5,595 in the multiple rehabilitation group), with 7,683 patients contributing to the total mortality outcome
• Mean age: 53 years (exercise only group) and 56 years (comprehensive cardiac rehabilitative group)
• Sex: Majority male (96% male in exercise only and 89% in comprehensive cardiac rehabilitation groups)
• Ethnicity: Not provided.

 

• 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, 95% CI 0.54 to 0.98). Comprehensive cardiac rehabilitation reduced all cause mortality, but to a lesser-13%, and non-significant degree (OR 0.87, 95% CI 0.71 to 1.05).
• Total cardiac mortality was reduced by 31% (random effects model OR 0.69, 95% CI 0.51 to 0.94) and 26% (random effects model OR 0.74, 95% CI 0.57 to 0.96) in the exercise-only and comprehensive cardiac rehabilitation interventions when compared to usual care. When subdividing cardiac deaths into those from coronary heart disease, there was a 35% and 28% reduction in mortality for exercise-only and comprehensive cardiac rehabilitation interventions, respectively. No significant effect was seen with either intervention on sudden cardiac deaths (however, only 18 trials reported this as an outcome).
• No evidence of an effect of the interventions (exercise-only and comprehensive cardiac rehabilitation) on the occurrence of non-fatal MI
• Using a combined outcome of mortality, non-fatal MIs and revascularizations (CABG and PTCA), a pooled-effect estimate of 0.81 (0.65, 1.01) for the exercise-only rehabilitation group and 0.81 (0.69, 0.96 random effects model) for comprehensive cardiac rehabilitation was found. Thus, cardiac rehabilitation results in a 20% reduction in "pooled adverse" clinical outcomes.
• There was a significant net reduction in total cholesterol in the comprehensive cardiac rehabilitation group (pooled WMD random effects model -0.57mmol per L (-0.83, -0.31)), but not the exercise-only group (pooled WMD -0.03mmol per L (-0.27, 0.22)). Neither intervention had any significant effect on HDL cholesterol.
• LDL was significantly reduced in the comprehensive cardiac rehabilitation group (pooled WMD random effects model -0.51mmol per L (-0.82, -0.19)), with no significant effect of intervention in the exercise-only rehabilitation group. However, LDL cholesterol was only measured in only two small trials in the exercise-only group and in six trials in the comprehensive cardiac rehabilitation group.
• There was a small, but significant reduction in triglycerides in the comprehensive cardiac rehabilitation group (pooled WMD random effects model -0.29 (-0.42, -0.15)). However, triglycerides were only measured in five trials and two trials in the exercise-only group showed no effect.  

• Exercise-based cardiac rehabilitation is effective in reducing cardiac deaths. It is not clear from this review whether exercise-only or a comprehensive cardiac rehabilitation intervention is more beneficial.
• The reasons for the differences between the two interventions are unclear. Differences may be due to different medications taken during the trial period. They are generally not well-reported, but are in part, dependent on when the trials were carried out and what medication was prescribed. With comprehensive cardiac rehabilitation, there was a significant reduction in both total blood cholesterol and LDL cholesterol, however, the effect of cholesterol-lowering drugs cannot be excluded. No effect of exercise-only rehabilitation was seen for total or LDL cholesterol.
• The population studied in this review is still predominantly male, middle-aged and low risk. Identification of the ethnic origin of the participants was seldom reported. It is possible that patients who would have benefited most from the intervention were excluded from the trials on the grounds of age.

Government:

NIH

 Limitations:

• On some outcome measures, limited number of trials and small sample sizes. For example, although there was a small, but significant reduction in triglycerides (TG) in the comprehensive cardiac rehabilitation group, this was based on only five trials with 500 patients in the comparison group. In the exercise-only intervention group, TG were measured in only three trials with one trial showing favorable effects of exercise on TG levels and two trials (including one larger study) found no effect.
• Generalizabilty: Majority of participants were male (96% in exercise-only and 89% in comprehensive cardiac rehabilitation group), and individuals less than 65 years of age (mean age 53 and 57 years, exercise-only and comprehensive cardiac rehabilitation, respectively). It may be possible that under-represented groups (women, older adults, and patients with co-morbidity) may benefit from the intervention.
• Other factors such as medications, other interventions such as intensive dietary changes, stress management techniques and education prior to the intervention may have affected the results.