group of panel members (panel co-chairs and subcommittee chairs), rereviewed all selected reports prior to final review by the entire panel of all abstracted scientific evidence pertaining to each intervention as it related to each outcome. The reports of scientific evidence addressing each cardiac rehabilitation intervention were reviewed as a group; conclusions were reached by the entire panel regarding the outcomes described to result from each intervention. When appropriate and necessary, expert opinion was formally derived from the panel to supplement or balance the conclusions reached from review of the scientific evidence. This Clinical Practice Guideline clearly identifies when expert opinion was used to substantiate a recommendation. Strength-of-Evidence Ratings The panel assigned a letter grade, designating the strength of the scientific evidence, for each guideline recommendation. Ratings reflect both the quality of the studies, including study design and methods used, and the consistency of the results of the scientific evidence: A Scientific evidence provided by well-designed, well-conducted, controlled trials (randomized and nonrandomized) with statistically significant results that consistently support the guideline recommendation. B Scientific evidence provided by observational studies or by controlled trials with less consistent results to support the guideline recommendation. C Expert opinion that supports the guideline recommendation because the available scientific evidence did not present consistent results, or controlled trials were lacking. The panel acknowledges that many important questions related to patient management decisions do not have a strong research basis. Therefore, the rating format does not necessarily reflect the importance of the guideline recommendation to patient care. This importance is conveyed through the use of careful wording in each guideline recommendation. Meta-analyses were not commissioned in the development of this guideline. The panel decided that meta-analysis was not indicated because of the considerable differences in patient populations, study designs, intervention techniques, and lack of details in many reports. These problems challenge the validity of applying meta-analytical techniques to this database. Furthermore, cardiac rehabilitation interventions are multifactorial, and the interrelated effects of the interventions or elements make the contribution of each specific intervention to the outcome difficult to quantify. Finally, the pronounced temporal changes in both the acute and the long-term treatment of patients with CHD over the decades in which the cardiac rehabilitation studies were conducted provided additional justification not to use meta-analytical methods. Instead, a comparison of benefits and harms was undertaken for each intervention component of cardiac rehabilitation services, when the scientific evidence enabled such comparison. Several draft versions of this guideline were reviewed by 41 health professionals to comply with the process of peer review. Peer review occurred on two separate occasions as the guideline was developed. The detailed comments of the peer reviewers were addressed by the panel and incorporated into the guideline. 2 Effects of Cardiac Rehabilitation Exercise Training This chapter discusses the effects of exercise training on exercise tolerance; strength training; exercise habits; symptoms; cardiovascular risk factors including smoking, lipids, body weight, and blood pressure; psychological well-being; social adjustment and functioning; return to work; morbidity and safety; mortality and safety; pathophysiologic measures; patients with heart failure and cardiac transplantation; and elderly patients. Exercise Tolerance RECOMMENDATION Cardiac rehabilitation exercise training consistently improves objective measures of exercise tolerance, without significant cardiovascular complications or other adverse outcomes. Appropriately prescribed and conducted exercise training is recommended as an integral component of cardiac rehabilitation services, particularly for patients with decreased exercise tolerance. Continued exercise training is required to sustain improved exercise tolerance. Scientific Evidence (Strength of Evidence = A). One hundred fourteen scientific reports addressed the effect of cardiac rehabilitation exercise training on measures of exercise tolerance. Of these, 46 were reports of randomized controlled trials, 25 of nonrandomized controlled trials, and 43 of observational studies. Randomized Controlled Trials Thirty-five of the 46 randomized controlled trials compared cardiac rehabilitation exercise training (with and without other rehabilitation services) with a no-exercise control group. The 11 remaining randomized controlled trials evaluated other issues pertaining to exercise training such as comparison of various intensities of exercise training or exercise training as a sole intervention compared with multifactorial cardiac rehabilitation. Of the 35 exercise-training versus no-exercise randomized controlled trials, 13 of the 14 U.S. studies reported statistically significant improvement in exercise tolerance in exercise versus control patient groups. 11,12,36,39,62,68,69,146-151 One U.S. trial reported no significant difference between exercise and control subjects.106 Statistically significant improvement in exercise tolerance also was reported in 17 of the 21 non-U.S. trials.9,10,17,18,22,37,42,43,57,74,75,152-157 One additional non-U.S. trial that reported significant improvement in exercise tolerance did not provide measures of statistical significance.50 U.S. and non-U.S. trials are described separately because of the differences in medical and social systems. Thus, 30 of 35 randomized controlled trials that compared exercise training versus no exercise documented a statistically significant improvement in exercise tolerance in intervention versus control patients. These randomized controlled trials are summarized in Tables 1 and 2. The proportion of randomized controlled trials that documented benefit for intervention versus control patients is displayed in Figure 2, which compares (a) U.S. and non-U.S. studies, (b) multifactorial versus exercise-only studies, (c) studies that specified exercise intensity versus those that did not, and (d) studies that used various durations of exercise training. As shown in Figure 2, 12 of the 16 multifactorial rehabilitation trials documented a statistically significant increase in exercise tolerance in the intervention compared with control groups, as did 18 of the 19 exercise-only trials. Twenty-five of the 26 randomized controlled trials that specified exercise intensity, using 60-90 percent of the peak heart rate at baseline exercise testing, demonstrated benefit for the intervention patients. Five of the nine randomized controlled trials that did not specify exercise intensity failed to demonstrate benefit in exercise tolerance in intervention versus control patients. Thus, five of the six studies that showed no difference between intervention and control patients did not specify exercise intensity in the study methodology. As shown in Figure 2, 10 of the 12 trials that involved 8–12 weeks of exercise training, as well as 16 of the 18 longer duration exercise-training studies, reported a statistically significant increase in exercise tolerance favoring intervention versus control patients. None of the 35 randomized controlled trials that compared exercise training with a no-exercise control group reported a statistically significant greater improvement in exercise tolerance in the control versus the intervention group. The effects of lower versus higher intensities of exercise training on exercise tolerance were evaluated in five randomized controlled trials. 15,60,61,158,159 Two reports were from the same clinical center. 60,158 The details of these studies are provided in Table 3. Three trials documented a significantly greater improvement in exercise tolerance comparing higher and lower intensity exercise prescription. 15,61,159 In one of these studies, although exercise tolerance at 8 weeks was greater with high-intensity exercise, there was no significant difference between groups at the 1-year followup.61 The two reports from the same study population found no significant differences in exercise tolerance between lower and higher intensity exercise training. 60,158 The frequency of exercise training in the 35 randomized controlled trials varied between two and seven times per week. The most common frequency was three times per week (19 studies), and the second most common was five times per week (8 studies). The weekly frequency of exercise did not relate to improvement in exercise tolerance. Of the five randomized controlled trials that did not demonstrate improvement in exercise tolerance with cardiac rehabilitation exercise training, one had an exercise frequency of two times per week,160 one had a frequency of three times per week,50 and the |