ABC | Volume 114, Nº5, May 2020

Arq Bras Cardiol. 2020; 114(5):943-987 Guidelines Brazilian Cardiovascular Rehabilitation Guideline – 2020 • Resistance training with low loads and a greater number of repetitions is considered safe for patients with CVD, although there is no solid evidence for patients with HCM. Some notes on drug therapy are warranted. Beta blockers and calcium channel blockers may be indicated in the treatment of HCM. As these medications attenuate the HR response to exercise, patients may experience a very reduced chronotropic response to exertion, which can cause increased exercise intolerance, suggesting a need for dosage adjustment. Excess diuretic use can be harmful because it increases the gradient of the outflow tract. Therefore, these agents should be used with caution. Like diuretics, exercise-induced dehydration can raise the outflow tract gradient; therefore, adequate hydration during training is of paramount importance. 6.6.2. Myocarditis The pathogenesis of myocarditis consists of three phases: acute myocardial injury, usually of viral etiology; host immune response; and recovery, or transition to fibrosis and dilated cardiomyopathy. Clinically, there is no clear distinction between these phases. The initial insult can cause acute myocardial damage, with impairment of contractility mediated by cytokines produced by the local inflammatory process. This acute inflammation may progress, in the late phase, to extensive fibrosis, which can cause ventricular dilatation and dysfunction. Acute myocarditis should be suspected when the following criteria are present: 283 • A clinical syndrome of acute HF, angina-type chest pain, or myopericarditis of less than 3 months’ duration • Unexplained rise in serum troponin • ECG changes suggestive of myocardial ischemia • Global or regional wall motion abnormalities and/or pericardial effusion on echocardiography • Characteristic changes in tissue signal on T2- or T1- weighted MRI, as well as late gadolinium enhancement. The participation of myocarditis patients in CVR programs after resolution of the acute phase has been the subject of very little study. There is no published research on the safety and effectiveness of this intervention. However, reports of CVR in this patient population have demonstrated benefits in quality of life and physical fitness, especially when there is functional impairment, even after improvement of the acute condition and optimization of drug therapy. 288-290 Before starting any exercise practice, patients with a history of myocarditis should undergo echocardiography, 24-hour Holter monitoring, and an exercise test no less than 3 to 6 months after the acute phase has resolved. 269,283 After this evaluation, selected cases may initiate moderate CVR, aiming at the general benefits obtained by patients with HF. In sports, it is reasonable for athletes to return to their normal training routine only if they achieve: return of systolic function to normal values; markers of myocardial necrosis and inflammation within normal range; and absence of clinically significant arrhythmias on both Holter monitoring and an exercise test. It is noteworthy that the clinical significance of persistent late gadolinium enhancement on MRI in post-myocarditis patients whose clinical symptoms have resolved remains unknown. Thus, it seems reasonable that those with small areas of enhancement and without significant arrhythmias on Holter monitoring and exercise testing can return to sports, provided that clinical monitoring is continued. 269 In chronic cases, in which ventricular dysfunction persists throughout the follow-up period, the patient should follow the general recommendations for CVR as described for chronic HF (see Table 6). 6.6.3. Other Cardiomyopathies 6.6.3.1. Arrhythmogenic Right Ventricular Cardiomyopathy Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disease that is associated with SCD in young adults and athletes. Pathologically, myocytes are lost and replaced with fibroadipose tissue, especially in the myocardium of the right ventricle, although isolated left ventricular or biventricular involvement may also occur. 291 There is evidence, in an experimental animal model, that exercise increases penetrance and risk of arrhythmias in patients with traditional ARVC mutations. 292 In individuals with positive genotypes, an increased risk of arrhythmias with exercise has also been confirmed. Ventricular tachyarrhythmias and SCD events in this condition usually occur during exertion, including sports and endurance exercise, with an increased risk of tachycardia, ventricular fibrillation, and HF. 293 It has been shown that individuals with ARVC who are involved in competitive sports experience a higher incidence of ventricular tachyarrhythmias and SCD, in addition to earlier symptom onset, compared with those who participated only in light physical activity and those who were sedentary. 270 The reduction in exercise intensity was associated with a substantial decrease in the risk of ventricular tachyarrhythmias or death, especially in patients without a detected desmosomal mutation and with an ICD for primary prevention. 294 Therefore, the scientific evidence suggests that participation in sports and intense exercise are associated with early onset of symptoms and an increased risk of ventricular arrhythmias and major events in patients with ARVC. Therefore, these patients must be disqualified from participation in sport. 269, 276 Regarding participation in CVR programs, there is no scientific data to indicate or suggest any benefits of physical exercise for patients with ARVC. On the other hand, keeping them sedentary, which contributes to low physical fitness, may also be inappropriate, as there is a general association of low physical fitness with mortality. 14,21 In a small observational study of patients with ARVC, there was no difference in mortality rate between inactive individuals and those who performed only recreational physical activities. 270 Thus, it can be assumed that participation in a supervised CVR program, restricted to exercise of light to moderate intensity, could not be harmful. Depending on other individual clinical characteristics, such as the presence of cardiovascular risk factors, physical exercises could be prescribed to control these conditions. 967