Results

A total of 1220 athletes were evaluated, with 825 soccer players, 226 soccer referees and 169 from different sports (including basketball, athletics and swimming). Ninety-six per cent were males, and mean age was 23±4 years (range 15–29). The average training time was 3 h per day, 3 days per week, over 10 years.

History: There were four cases with history of premature sudden death in a first-degree relative. Those deaths were not documented and therefore could not be attributed to cardiac cause. Three cases had effort syncope/near syncope and four cases had palpitations, with no associated clinical conditions and normal physical examination.

Physical examination: A systolic murmur >II/VI was found in four cases, which were referred for echocardiographic assessment. There were no cases of diastolic murmur, delayed femoral pulses or stigmata suggestive of Marfan syndrome.

ECG findings: Twelve-lead ECG was considered positive in the presence of one or more of the findings reported in table 1. According to these criteria, 75 players (6.14%) showed a positive ECG. The most common findings were repolarisation abnormalities (ST-segment depression or T-wave flattering or inversion in two or more leads), which constituted more than a half of the ECG disturbances reported (3.27% of the initial sample). Complete right bundle-branch block (0.73%) and right axis deviation (0.65%) were frequent abnormalities encountered. Five cases fulfilled voltage criteria for left ventricular hypertrophy and two showed left axis deviation, with two more cases of pathologic Q wave. Mean PR duration was 141 ms, with an SD of 30.2.

In four cases, a short PR interval was followed by a delta wave (two right posteroseptal morphology, two left lateral ones). None of them had family history of arrhythmia, nor had they ever had palpitations, syncope or any symptom suggestive of a pre-excitation syndrome. Mean QT duration was 383 ms (SD 24.6), with one case in the upper limit of normality (440 ms). Personal and family histories were both negative for rhythm disturbances. Other abnormalities related with conduction disorders were premature ventricular beats, which were found in four cases; no supraventricular tachycardia, atrial flutter or atrial fibrillation was encountered; nor were there pathologic sinus bradycardia or atrioventricular blocks.

Echocardiographic findings: Ninety players were referred for echocardiographic assessment because of abnormal preparticipation screening findings (table 2). The mean ventricular septal thickness was 11 (2) mm (8–23 mm), with eight cases fulfilling criteria of left ventricular hypertrophy (septal thickness >13 mm), one case of athlete's heart (enlarged ventricular dimensions, normal diastolic, systolic and right ventricular function, septal thickness 13–15 mm) and one case of HCM (case 1) (septal thickness 23 mm, diastolic dysfunction, without mitral regurgitation, systolic anterior movement of mitral valve or subaortic gradient). However, six cases remained in a blurred group called the “grey area” because echocardiographic findings were not sufficient to confirm or exclude diagnosis of cardiomyopathy (13–15 mm septal thickness, non-dilated left ventricle, with normal systolic and diastolic function). Further evaluation was required.

Additional tests: An exercise test was performed in five cases because of ECG abnormalities suggestive of rhythm disorders. Four players showed short PR interval followed by delta wave on baseline ECG, raising suspicion of pre-excitation syndrome. The pre-excitation disappeared suddenly with exercise, thus revealing that the accessory pathway had a relatively long refractory period and was unlikely to precipitate arrhythmias. The fifth case was a player with QT duration in the upper limit of the normality, where physical activity showed its progressive shortening within normal values. The five players underwent a 24-h ECG with normal results. According to the low-risk findings on non-invasive assessment, these asymptomatic players were allowed to participate in competitive sports. They received counselling, and no further examination (electrophysiological study) was practised.

The six cases included in the “grey area” underwent a genetic test with sequentiation of myosin binding protein (MYBPC), with negative results. These findings excluded HCM related to MYBPC but could not rule out other mutations that have been described in association with this form of disease. MRI in one of those cases confirmed an apical variety (type VI) of HCM (case 2), according to the degree and distribution of hypertrophy. A detraining period has been recommended in the remaining five individuals in the “grey area” and may help to better classify them as having athlete's heart or a pathological form of cardiac hypertrophy. Diagnosis of athlete's heart would be favoured by involution of ECG abnormalities and/or reduced cardiac mass with detraining. The exactly duration for the deconditioning period remains unclear. On the basis of previous data,4 we established a period of at least 3 months, with clinical re-evaluation and serial echocardiographic assessment.

Familial screening with genetic analysis and echocardiographic evaluation were performed in first-degree relatives of the two cases with a diagnosis of HCM.

Case 1: Genetic analysis revealed a mutation for MYBPC3 (Arg 495 Trp in 18 exon), which was present in the index case, his mother and his grandfather. The latter also showed echocardiographic criteria for HCM.

Case 2: Both genetic test and echocardiographic assessment were negative in the relatives studied.