Athletes with small interatrial or interventricular defects (open or after closure), normal right heart volume, and no pulmonary hypertension and those with a large atrial septal defect and normal pulmonary artery pressure can participate in all competitive sports. Athletes with atrial septal defect and mild pulmonary hypertension can only take part in low-intensity competitive sports, and so they must be excluded from football competitions. Pulmonary hypertension is defined here as a mean pulmonary artery pressure >25 mm Hg or a pulmonary vascular resistance index of >3 Wood units [16]. Patients with an associated pulmonary vascular obstructive disease who have cyanosis and large right-to-left shunt should not participate in competitive sports [5, 16]. Patients with hemodynamically insignificant patent ductus arteriosus (open or after closure) can take part in all competitive sports.

ECG changes occur in up to 80% of trained athletes due to an adaptation of the cardiac autonomic nervous system to exercise including sinus bradycardia or sinus arrhythmia. Profound sinus bradycardia (<30 beats/min) or marked sinus arrhythmia (pauses ≥3 s when awake) should be distinguished from sinus node dysfunction. In patients with third-degree AV block and Mobitz type II (type II second-degree), a thorough diagnostic evaluation is necessary.

There is no need to require systematic evaluation with echocardiography unless one or more of the following are present: relevant symptoms, family history of cardiovascular diseases or sudden cardiovascular death, or ECG criteria for pathologic left ventricular hypertrophy.

Further evaluation is required if suspected ostium secundum atrial septal defect, suspected arrhythmogenic right ventricular cardiomyopathy (incomplete right bundle branch block pattern associated with T-wave inversion beyond V2 to leads V3 and V4 or when accompanied by premature ventricular beats with left bundle branch block morphology), or suspected Brugada syndrome. Brugada syndrome is characterized by J wave (slow, positive deflection at R-ST junction) most perceptible in leads V1 and V2 with minimal to no changes in other leads. Diagnosis of Brugada syndrome may be confirmed by drug challenge with sodium channel blockers. In the presence of Brugada-like ECG abnormalities, analysis of ST-T segment waveform can usually differentiate between Brugada ECG and right precordial early repolarization that appears in the athlete. Brugada syndrome is characterized by downsloping ST segment with STJ/ST80 ratio > 1 [17]. Athletes show upsloping ST segment with mean STJ/ST80 ratio ≤ 1 [17]. It is obligatory to refer athletes with suspected Brugada ECG to a cardiologist with electrophysiologist knowledge for evaluation, including family history evaluation, risk stratification, and pharmacologic test with sodium channel blocking.

Usually, there is no need to further clinical evaluation if there is the presence of early repolarization, that is, a benign ECG pattern in young people and athletes. Typical characteristics of right precordial ST-T changes of early repolarization in trained athletes can easily be differentiated from arrhythmogenic right ventricular cardiomyopathy and Brugada syndrome. An ECG pattern of early repolarization in inferior/lateral leads associated with prominent terminal QRS slurring should be evaluated for idiopathic ventricular fibrillation.

If there is evidence of ST-segment depression on resting ECG (isolated or with T-wave inversion), it requires further investigation to exclude heart disease, right atrial enlargement, and right ventricular hypertrophy and implies further assessment for congenital or acquired heart disease [17]. In the case of presence of T-wave inversion with deep inverted T waves ≥ 2 mm in two or more adjacent leads, it may indicate inherited heart muscle disease requiring clinical evaluation, the study of the family, and mutation analysis when appropriate. T-wave inversion in inferior (L2, L3, aVF) or lateral leads (L1, aVL, V5, V6) is uncommon and requires further evaluation to rule out underlying heart disease. It is significant to note that minor T-wave abnormalities <2 mm in two or more leads are uncommon in athletes (occur in <0.5%) but are often seen in cardiomyopathy and may be present before evident structural changes in heart intraventricular conduction abnormalities [17]. Evidence of complete bundle branch block (QRS duration ≥ 120 ms) or hemiblock also implies cardiac assessment to evaluate for underlying pathologic causes, including exercise testing, 24-h ECG, and imaging. When bifascicular block pattern is present, it is prudent to perform ECG on athlete’s family to exclude Lenègre disease, an autosomal dominant progressive cardiac conduction disease. Nonspecific intraventricular conduction abnormalities (prolonged QRS > 110 ms) may be indicative of heart muscle disease (such as ARVC) and imply further investigation [17]. Ventricular preexcitation (Wolff-Parkinson-White) assessment should include symptoms (syncope or palpitation) and family history of cardiomyopathy, preexcitation, or sudden death. To assess the risk of arrhythmia and corroborate diagnosis, it is mandatory to make 24-h ECG, exercise testing, adenosine/verapamil testing, and electrophysiological study for inducible atrioventricular reentrant tachycardia and refractory nature of the accessory pathway [17]. If there is a long QT interval, it is crucial to be aware that a corrected QT interval ≥ 500 ms is indicative of acquired or congenital long QT syndrome despite family history or symptoms including syncopal episodes. Corrected QT interval > 440 ms in male athletes and > 460 ms in female, but < 500 ms requires further assessment for diagnosis [17]. Exercise testing may assist in diagnosis confirmation [17]. In the case of short QT interval (≤ 380 ms), further evaluation is necessary to rule out metabolic causes and drugs. Of note is that short QT interval could be associated with anabolic androgenic steroid abuse in trained athletes. If there is no visible acquired source, refer the athlete for familial ECG screening and molecular genetic evaluation [17].

Correct risk stratification and relevant sports ineligibility are based on the evidence that sudden death may be the first clinical manifestation of HCM, particularly in the young (<30 years). This disease is defined as unexplained left ventricular hypertrophy in the absence of other cardiac or systemic conditions that lead to ventricular wall thickness. The clinical features that support the diagnosis of HCM in the differential with hypertensive cardiomyopathy include several items. These are the familial history, the presence of right ventricular hypertrophy, late gadolinium enhancement at insertion point of the right ventricle or in localized segments of maximum thickness of the left ventricle in cardiac NMR, maximum LV wall thicknesses of 15 mm or more in whites and 20 mm in blacks, severe diastolic dysfunction, and severe disturbances of repolarization and conduction or pathological Q waves in the ECG.

In athletes under the age of 30, HCM is the first cause of sudden death (reaching more than a third of total) [18]. Preparticipation screening will increase the number of suspected cases of HCM and allow a final diagnosis in more cases. Lethal ventricular arrhythmias generally cause sudden death. High-intensity exercise may be the trigger of the arrhythmia and is considered a risk factor for sudden death. The signs and symptoms, natural history, and prognosis in HCM are variable. The estimation of risk based only on phenotypic expression is difficult. The occurrence of sudden death in a family member is a marker of high risk for all affected members. Some cases are not genotypically affected, but this is a rare finding. HCM is inherited as a Mendelian autosomal dominant trait. It should be noted that the risk associated with exercise for athletes with cardiovascular diseases is difficult to quantify, given the various situations to which individual athletes may be exposed (degree of hydration, electrolytes variations, catecholamine levels).

There can be more than 1500 mutations in any one of 11 genes which encode proteins of the sarcomere (the contractile unit of cardiac muscle), the components of which are thick or thin myosin filaments with contractile, structural, or regulatory functions, adjacent Z-disk, and calcium handling [19]. The three most common HCM-causing mutant genes are the α-myosin heavy chain, cardiac troponin T, and myosin-binding protein C. Some genetic mutations such as cardiac troponin T mutations are associated with a particular adverse prognosis. Other genes account for a minority of HCM cases, including cardiac troponin I, myosin light chains, titin, α-tropomyosin, α-actin, and α-myosin heavy chain [20]. Along the substantial number of mutant genes, there is an HCM intragenic heterogeneity: most of the mutations are missense, where a single amino acid residue is substituted with another. Myocyte disarray, fibrosis, and small vessel disease are the most common pathological features [21]. The prognostic value of mutations in asymptomatic carriers with mild or absent phenotypic expression of the disease is uncertain, but it is considered to be low. Genetic testing for the most important mutations has become available as several commercial kits. Identifying the genes responsible for HCM was thought to improve risk stratification but is now admitted that single mutations do not predict prognosis in an accurate mode. Double mutation carriers may have a higher risk of sudden cardiac death.

Diagnosis is mainly established by noninvasive cardiac imaging, namely, echocardiography and NMR. Diagnosis of HCM is based on the echocardiographic observation of the typical feature of the disease: asymmetric hypertrophy of the left ventricle (LVH), with diastolic dysfunction in association with a normal left ventricle (LV) dimension, in the absence of other cardiac or systemic diseases like hypertension or aortic stenosis associated with LVH. The presence of a systolic murmur, a systolic anterior motion of the mitral valve or a premature closure of the aortic valve is not, per se, diagnostic criteria. Most patients do not have LVOT obstruction at rest, and most of the well-documented physical findings like a systolic murmur and bifid arterial pulse are limited to patients with outflow gradients. LVH nevertheless is an independent risk factor for sudden death in young people affected by HCM and is variable in distribution and extension [18, 19]. Many patients show diffusely distributed LVH. However, almost one-third of patients have only mild wall thickening confined to a single segment. Increased left ventricle wall thicknesses range from mild (13–15 mm) to massive (30 mm [normal, ≤11 mm]) and up to 60 mm. European guidelines [1, 17] recommend a wall thickness ≥15 mm for adults to access an HCM to be diagnostic. It is relevant to note that morphological features of HCM may not be present and identified by echocardiography until adolescence, and the probability of diagnosis increases with age.