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 inappropriate shocks may occur due to the double-counting phenomenon (QRS complexes and T-waves). 190,191 Regarding exercise recommendations, participation in competitive sports may be considered for short QT patients as long as they are asymptomatic, have been under treatment for 3 months and precautionary measures are taken (automatic external defibrillator). Recommendation grade: IIa. Evidence level: C. 5.4. Brugada Syndrome This syndrome is characterized by the occurrence of syncope or SD caused by polymorphic ventricular tachycardia in structurally normal hearts. Its diagnosis may be based on a specific EGC pattern, defined as an ST-segment elevation ≥ 2mm (0.2 mV) in the right precordial leads. However, this diagnosis may be unstable. 192 Its most peculiar aspect is J-spot elevation in the right precordial leads (V1 to V3), although this phenomenon has also been described in lower leads. 193-195 However, the ECG results may be unimpressive, requiring the use of sodium channel blockers to unmask the condition. The tracking and proper identification of these patients are essential, since SD is rarely the first symptom. 192 This syndrome is highly influenced by gender, since 90% of cases occur in men. To date, only functional loss mutations in SCN5A, present in about 20% of those affected, have been identified. Currently, a total of 23 genes have been implicated in Brugada syndrome (BrS1-BrS23), and the vast majority of them are very rare. 196 Clinically, the disease manifests with syncope or SD, predominantly in the third or fourth decade of life, with fever as a trigger for arrhythmias. In risk stratification, individuals with spontaneous J-point elevation have a worse prognosis than those in whom the typical pattern was observed only after infusion of flecainide, procainamide or ajmaline. The occurrence of syncope, associated with spontaneous J-point elevation, increases the risk of SD by up to 6 times. Neither a family history of SD nor detecting a mutation in the SCN5A gene proved useful for risk stratification. 197,198 Sports have not been described as a SD risk factor in Brugada syndrome. However, since there is a greater risk of events related to parasympathetic activity in this syndrome, arrhythmias can occur after exercise/training, a point in which there is vagal recovery and sympathetic withdrawal. In addition, significant elevations in body temperature due to intense physical activity in unfavorable environments may also trigger SD. Defibrillators are recommended for: Aborted SD patients. Recommendation grade: I. Evidence level: B. Patients with spontaneous J-point elevation and syncope, or with previously documented ventricular tachycardia. Recommendation grade: IIa. Evidence level: B. Exercise and competitive sports may be considered for Brugada patients, provided they are asymptomatic and have been undergoing treatment for 3 months. Recommendation grade: IIa. Evidence level: C. 5.5. Catecholaminergic Polymorphic Ventricular Tachycardia Catecholaminergic polymorphic ventricular tachycardia (CPVT) is triggered by physical exertion or emotional stress in children and young adults with structurally normal hearts. 199,200 The patient’s resting ECG will appear normal, except for relative bradycardia for age and frequent U-waves. The disease manifests clinically as syncope. 199 At least four mutations have been described in several genes (RyR2, CASQ2, TRDN, CALM1) that potentially cause CPVT. The most common cause is functional gain mutation in RyR2 (about 60% to 75% of cases), the gene that encodes type 2 ryanodine receptor, which is the protein responsible for releasing calcium from the sarcoplasmic reticulum. Anomalies in the CASQ2, the gene that encodes cardiac calsequestrin, which is a calcium-binding protein in the sarcoplasmic reticulum, account for up to 5% of CPVT cases. The CALM1 gene encodes calmodulin, a protein that binds to calcium and stabilizes the RyR2 channel, and accounts for less than 1% of the cases. Finally, there is also the TRDN gene (identified in two families with CPVT), which encodes triadin, a protein that binds RyR2 and calsequestrin to the sarcoplasmic reticulum. 201-203 Genetic analysis does not contribute to risk stratification, but it is important for identifying mutation carriers that have not yet manifested symptoms. The initial presentation of about 30% of patients is SD, and up to half of the patients suffer cardiac arrest between the ages of 20 and 30 years. 204 CPVT is a penetrating disease, and the prevalence of “silent” cases could be up to 20%. 205 However, cardiac events may occur even in this subgroup of individuals, who should be treated according to current guidelines. In these cases, genetic analysis plays a central role. 206,207 Arrhythmias during exercise are the typical manifestation, frequently 120 to 130 beats per minute, beginning with isolated ventricular extrasystoles and progressing to episodes of unsustained and sustained ventricular tachycardia if effort is continued, usually with 180° rotation in the front plane (bidirectional). Atrial arrhythmias, atrial fibrillation and supraventricular tachycardia are also common in the syndrome. Beta-blockers, the main therapeutic pillar for CPVT, 208,209 are very effective and are recommended for: Patients with clinical manifestations. Recommendation grade: I. Evidence level: B. Asymptomatic mutation carriers. Recommendation grade: IIa. Evidence level: B. 347