ABC | Volume 114, Nº5, May 2020

Arq Bras Cardiol. 2020; 114(5):943-987 Guidelines Brazilian Cardiovascular Rehabilitation Guideline – 2020 6.3. Stable Coronary Artery Disease after an Acute Event or Revascularization Cardiovascular disease (CVD), led by coronary artery disease (CAD), is responsible for the majority of deaths in the adult population worldwide. 122-124 The underlying mechanisms of stable CAD include atherosclerotic obstruction of the epicardial vessels, microvascular disease, and coronary spasm, either alone or in combination. 5 Clinically, the most common manifestation of stable CAD is angina pectoris, which is characterized by reversible episodes of chest pain due to myocardial ischemia, resulting from the imbalance between myocardial oxygen supply and consumption, usually triggered by physical exertion or emotional stress, which resolve with rest or the administration of fast-acting nitrates. 5 Stable CAD has a good prognosis, with annual mortality estimated at 1.5% and a nonfatal infarction incidence of 1.4%. 125 Nonetheless, full clinical treatment is essential, including optimization of drug therapy and regular physical exercise, in addition to other behavioral changes to address smoking, diet, and body composition. Elective revascularization (whether surgical or interventional) may also be indicated in patients with stable CAD, depending on their symptoms and cardiovascular risk. 5 However, it is worth noting that, in stable patients, even those with angina, exclusively clinical treatment has not been shown to be inferior to treatment with the addition of an interventional approach. 70,126,127 Development of an acute coronary syndrome, with AMI or unstable angina, is associated with increased cardiovascular risk and may require adjustment of drug therapy plus urgent surgical or percutaneous revascularization. 128-131 6.3.1. Therapeutic Benefits of Physical Exercise The short- and long-termbeneficial effects of regular physical exercise in patients with stable CAD have been demonstrated in the scientific literature. During the first 8 to 12 weeks of CVR, there is a marked increase in ischemic threshold, 132-136 improvement of cardiorespiratory functional capacity, 132,134,136 and improvement in myocardial perfusion imaging. 137-140 These benefits persist as long as regular physical exercise is maintained, 103,141-144, which contributes to improvement in quality of life 1,146 and reduction of hospitalization and mortality from cardiovascular causes. 1,144,146-148 In patients with stable CAD, different mechanisms explain the increase in ischemic threshold, which gradually allows physical activity at higher loads. Reduction of the double product at submaximal loads is associated, among other mechanisms, with an improvement in cardiac autonomic modulation. 144 Myocardial perfusion increases due to an improved endothelium-dependent vasodilator response 149-151 and increased recruitment of collateral vessels during exercise, 134,144,152 which is reflected in the reduction of ST segment depression during exercise. 35,132,137 It is also notable that the combination of physical training and a low-fat diet can influence the progression of atherosclerotic plaque. 152,153 CVR is an adjunctive therapy that is also effective after acute coronary events and surgical or percutaneous revascularization. A systematic review and meta-analysis 1 of 63 studies involving 14,486 patients aged 47–71 years revealed that CVR reduced cardiovascular mortality by 26% and overall hospitalization rates by 18%, with additional improvement in quality of life. In this population, CVR should be encouraged whenever possible. The improvement in cardiorespiratory fitness is one of the factors responsible for reduction of all-cause mortality after CVR. In a cohort of 5,641 CVR patients in Canada, every 1 MET increase in cardiorespiratory capacity was found to decrease all-cause mortality by 25%. 154 Other similar studies reported reductions in cardiac or all-cause mortality on the order of 8–34% for each MET of improvement in cardiorespiratory fitness. 155,156 In addition, CVR provides an add-on effect to reduce cardiovascular events after coronary angioplasty, as demonstrated in the ETICA trial (Exercise Training Intervention After Coronary Angioplasty). A 26% increase in VO 2 peak, 27% improvement in quality of life, and 20% reduction in cardiac events, including fewer AMIs and fewer hospitalizations, were observed in patients who underwent CVR after angioplasty when compared to those who remained sedentary. 157 6.3.2. When Is Rehabilitation Indicated? CVR is indicated in all cases of CAD (Table 5). It is considered useful and effective both when it consists exclusively of physical exercise and when educational content, management of risk factors, and psychological counseling are added. 146 Despite increasingly early interventional treatments and decreased length of hospital stay after acute coronary syndromes, it is not uncommon for patients to begin rehabilitation only after outpatient follow-up with their primary physician, which may mean 15 days or longer after the event. Early initiation of CVR is possible, and can have a direct, positive influence on adherence and on the degree of clinical benefit achieved after the acute event. One of the greatest concerns of early CVR refers to the effect of physical training on the ventricular remodeling process. While some authors report negative effects, 163 others report neutral 139 or even positive effects 158,164 on this process. A systematic review and meta-analysis 159 carried out to answer this question found that the changes observed in ventricular function, ventricular diameter, and functional capacity were directly related to the timing of CVR initiation. The greatest benefits in ventricular remodeling and functional capacity were obtained when programs were started in the acute phase (6 hours to 7 days) after the event, declining when initiated 7–28 days after the event and even further after 29 days, at which time the positive effect on ventricular remodeling was progressively lost. It is important to note that there was no difference in events between the initial training phases and that the sample studied was primarily composed of young men, which highlights the need for further studies, especially in other populations (such as older adults and women). For every 1-week delay in initiation of CVR after an AMI, an additional 1 month of training may be necessary to achieve similar benefits in end-systolic volume and left ventricular ejection fraction (LVEF). 160 957