ABC | Volume 112, Nº3, March 2019

Updated The Brazilian Society of Cardiology and Brazilian Society of Exercise and Sports Medicine Updated Guidelines for Sports and Exercise Cardiology - 2019 Arq Bras Cardiol. 2019; 112(3):326-368 advanced atrioventricular block, asystole, and myocardial infarction may also be the cause of this undesired event. 4.1.1. Genetics and Hypertrophic Cardiomyopathy At present, at least 20 genes have been implicated in the genesis of this disease, 95 and more than 1,700 mutations related to contractile myocardial protein have been discovered. Mutations in at least 11 different genes that code for sarcomeric proteins have been identified in up to 70% of family cases. 96,97 Mutations of genes in the beta-myosin heavy chain (MYH7) and myosin-binding protein C (MYBPC3) are the most frequent. Together, MYBPC3 and MYH7 account for up to half of all clinically recognized cases of HCM, and make up at least 75% of the index cases in which a mutation is identified. 98 Other less frequent mutations are related to the troponin I and troponin T genes (TNNI3, TNNT2) and alpha-tropomyosin-1 (TPM1), whose frequency is often less than 5%. Still less common (less than 1%) are mutations of muscle LIM protein (CSRP3), troponin C (TNNC1) and titin (TTN). Genetic phenotypes such as Fabry disease, amyloidosis, Danon disease and Friedreich ataxia should also be considered. 95 Mutations in troponin genes, although less common (15% to 30%), have been most closely associated with SD, 99 including, in some reports, individuals with no phenotypic manifestations of the disease. Genetic counseling by a multidisciplinary team experienced in genetically determined heart disease is recommended for individuals with HCM. Recommendation grade: I. Evidence level: C. Genetic sequencing study for patients with clinically diagnosed HCM (index cases). Recommendation grade: I. Evidence level: B. Assessment for specific mutations in direct relatives of patients diagnosed with genetically determined HCM. Recommendation grade: I. Evidence level: B. 4.1.2. Complementary Exams in Hypertrophic Cardiomyopathy 4.1.2.1. Electrocardiogram ECG should be performed in all patients with suspected HCM. Recommendation grade: I. Evidence level: B. About 90% of patients with HCM have ECG changes, with ST-segment and T-wave being the most common. Athletes with HCM have a higher prevalence of T-wave changes (especially deep T-wave inversion in the lateral leads) and ST-segment changes than non-athletes with the disease. In addition to these changes, there is left atrial enlargement, which is identified by a prolonged P-wave duration (> 120 ms) in leads I or II with a negative P-wave portion ≥ 1 mm in depth and ≥ 40 ms in duration in the V1 lead. Complete left bundle branch block may also be suggestive of HCM. In the past, some ECG changes in athletes were considered potentially pathological, such as: left atrial enlargement and left axis deviation, T-wave inversion confined to V1-V4 preceded by J-point elevation (especially in blacks), Q-waves ≥ 3 to 4 mm (with an amplitude less than one-quarter of the R-wave and a duration < 0.04 s). However, such changes are now considered physiological responses in the athlete’s heart, and do not require additional clinical evaluation. 100,101 4.1.2.2. Echocardiogram This exam play a fundamental role in HCM assessment. In addition to the degree of hypertrophy, they can determine the gradient between the left ventricle (LV) and the aorta, as well as the presence of mitral valve abnormalities: systolic anterior motion and altered patterns of diastolic function. 93,102 Echocardiograms also have an important role in differentiating between hypertrophy due to HCM and that due to physical training (ventricular hypertrophy in the athlete’s heart). A variety information, such as the pattern and distribution of hypertrophy, parietal thickening, cavity size, assessment of diastolic function by tissue Doppler imaging, and family history are required. 103 When not clinically differentiated, ECG, echocardiograph, functional or other imaging methods, such as serial ECG, may be useful when evaluating athletes with suspected HCM before and after a detraining period (Table 8). 104 Regarding prognosis, LV wall thickness > 30 mm is a major risk factor for SD, especially in adolescents and young adults. 105 A gradient above 50 mmHg between the LV and the aorta is also associated with worse prognosis. 106 When comparing athletes and non-athletes with HCM from an echocardiographic point of view, athletes present the following characteristics: lower LV wall thickness, higher left ventricular end-final diastolic diameter and higher ejection fraction. 4.1.2.2.1. Transthoracic Doppler Echocardiogram Confirm clinical suspicions of HCM by determining parietal thickening and whether there is a dynamic gradient. Recommendation grade: I. Evidence level: B. Investigate the presence of HCM in first-degree relatives. Reassessment of clinical evolution, as well as therapeutic interventions. Recommendation grade: IIa. Evidence level: C. Annual reassessment of family members of HCM patients aged 12 to 18 years. 339