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 and potassium, complete lipid profile, uric acid, glutamic- oxalacetic transaminase, glutamic-pyruvic transaminase, gamma-glutamyl transpeptidase, bilirubin, prothrombin time/ international normalized ratio, and common urine testing. Recommendation grade: I. Evidence level: B. For individuals who exercise or compete at altitudes over 2,000 meters, it is important to perform hemoglobin electrophoresis to rule out the possibility of hemoglobinopathies (e.g., sickle cell anemia). In our country, especially in regions of higher incidence, serology for Chagas’ disease may also be recommended. 3 Chest radiography may also be requested in many cases. 2.3.1. Resting 12-Lead Electrocardiogram 2.3.1.1. Introduction Use of this examination in groups of younger athletes is controversial. Although the American Heart Association (American College of Cardiology/American College of Sports Medicine) does not include ECG in PPS, the European Society of Cardiology, in addition to numerous sports organizations, recommend it. 4,5 For master athletes, resting ECG is mandatory, since older adults have a higher prevalence of cardiovascular diseases, especially coronary artery disease (CAD). 26,27 2.3.1.2. Method Conventional 12-lead ECG should be performed with the individual in the supine position, recorded at a velocity of 25 mm/s and ideally obtained 24 hours after the last sporting activity. At least 5 minutes of rest is recommended before the examination. 3,28 2.3.1.3. Analysis Since there are peculiarities among the resting ECG results of athletes, examinations should be interpreted by physicians with experience in the area. This recommendation is important, because it will prevent common alterations of the athlete’s heart from being confused with heart disease. However, in most countries medical knowledge regarding the interpretation of athletes’ ECG is still limited, which prohibits broader application of this method. 29 2.3.1.4. Changes Regular intense exercise can cause physiological changes to the heart at structural, functional and electrical levels. The ECG findings of more than 80% of high-performance athletes reflect exercise-induced cardiac adaptations as a result of intrinsic changes in automaticity and atrioventricular conduction, 30 as well as of increased vagal tone and cardiac remodeling. Due to the establishment of criteria that allow a distinction between heart diseases and athlete’s heart syndrome, interpretations of athletes’ ECG are becoming more uniform. 28,31 It is understood that the false positives associated with athletes’ ECG depend on the criteria used in their interpretation, as well as our current understanding of variations of normality. Thus, new criteria represent a major effort to refine the analysis and interpretation of ECG, making it more specific without losing sensitivity. Variations in the prevalence of these criteria are related to gender (higher in males), age (genetic/congenital diseases in young athletes and CAD in master athletes), ethnicity (black athletes have more left ventricular overload and repolarization changes than athletes of other races), training level (variation is more frequent in professional athletes than amateurs) and type of sport (predominantly regarding the dynamic component). 28 It can be especially difficult to differentiate between physiological and pathological adaptations in black athletes, since they have a tendency to develop more hypertrophy in response to exercise than whites. We should also point out that more than 10% of black athletes may have a wall thickness > 12 mm in the echocardiogram. 32 Failure to distinguish between the physiological and the pathological can have harmful consequences. Athletes can be unnecessarily disqualified from competition due to ECG changes that could be considered normal. Likewise, they may undergo unnecessary examinations, which greatly increase their costs. On the other hand, signs of life-threatening cardiovascular disease may be erroneously interpreted as normal variants of an athlete’s ECG, which could put the individual at risk of SD. Changes in the athlete’s ECG can be divided into two groups: common and/or related to training; or uncommon and/or suggestive of heart disease (Table 2). ECG is most useful when performed as part of PPS, when it can identify unexpected changes, such as previous myocardial infarction (in older age groups), arrhythmias, conduction disorders, etc. An ECG may also help diagnose less prevalent diseases, such as hypertrophic cardiomyopathy (HCM), long QT syndrome, short QT syndrome, Brugada syndrome, Wolff-Parkinson- White syndrome (or other pre-excitation syndrome), in addition to arrythmogenic right ventricular dysplasia (ARVD). A 12-lead ECG may also facilitate assessment of significant atrioventricular and intraventricular conduction and rhythm disturbances. It can also detect ST-segment changes, such as early repolarization, T-wave inversion in precordial and/ or peripheral leads, and voltage criteria suggestive of left ventricular hypertrophy (LVH). 28,31 There may be variations in the prevalence of EGC changes, which are more frequent in men than women. In relation to age, we found a higher frequency of inverted T-waves in precordial and/or peripheral leads in master athletes and older adults, as well as criteria for LVH, in addition to conduction disturbances (Table 3). There are also significant variations in 12-lead ECG results in different types of sports. Recommendation grade: I. Evidence level: A. 2.3.2. Electrocardiogram: Physiological Changes vs. Changes Suggestive of Heart Disease Athletes frequently show ECG changes (up to 80% in some series), including: bradycardia/sinus arrhythmia (13% to 69%), first degree atrioventricular block (35%), and early 332