Cardiac structural and electrical adaptation in male active athletes. QT interval could it be the clue to sudden cardiac death?

In humans, cardiac morphological adaptations to athletes training have been exhaustively described. Top-level training is often associated with morphological changes in the heart, including increases in left ventricular chamber size, wall thickness, and mass. The increase in left ventricular mass because of training is called [athlete's heart]. Left ventricular structural changes in competitive athletes represent adaptation to hemodynamic overload induced by training and are consisted with different kinds of sport activity. Work capacity during exercise is positively influenced by preload increase in top-level endurance athletes, while increased after load due do isometric training in strength-trained athletes determines higher systemic resistance due do physical effect. This work aimed to study the effects of prolonged physical training on the structure of the heart. A cross-sectional comparative study had been conducted in Cardiology Department, Suez Canal University Hospital and included active and control subjects in Ismailia Governorate Clubs. The study included 27 competitive endurance active male athletes, 27 power active male athletes, and 27 male healthy control subjects leading an ordinary sedentary life. The study population were subjected to general clinical examination, electrocardiographic and echocardiograghic examinations. Standard resting 12-lead ECGs were obtained a few minutes before the echocardiography investigation and >/= 24 hours after the last athletic activity for active athletes. Results of electrocardioraphic data showed that PR intervals, QT interval QTc dispersion were significantly higher in active athletes than that in control subjects. These prolonged QTc dispersion may predispose to further ventricular arrhythmic events and sudden death. In this study, comparative assessment of electrocardrgraphic pattern was done between active athletes and control subjects. 74.1% of active athletes showed completely normal ECG while the remaining 25.9% showed minor alterations that have been consistently reported in trained athletes and that are regarded as part of athlete's heart syndrome. Comparing LVM and mass index in power versus endurance active athletes it was shown that LVM and LVMI were significantly higher in power active athletes. From the present study, we can conclude that there were certain structural adaptive changes occurring in athletic heart; these adaptive changes vary according to the type of training whether being mainly isometric or isotonic. In the former one, the heart adapts mainly by concentric hypertrophy, whereas training with isotonic [dynamic] exercise leads to eccentric hypertrophy. However, the geometric pattern of athlete's heart is more complicated than expected as there is overlap between isometric and isotonic activities. Our findings are most consistent with the benign and physiological nature of LV hypertrophy in athletes. But we can suggest that careful assessment of the QT interval may be a clue to sudden cardiac death in athletes. The 12-lead ECG has been suggested as a relatively simple and inexpensive test to strengthen the limited diagnostic efficacy of the medical history and physical examination

Global cardiac functional adaptation in male active athletes as determined by Tei index

It has been known for a long time that physical conditioning induces numerous cardiovascular adaptations which characterize the [athletic heart]. Therefore, the present study was directed to study the adaptation of prolonged physical training [more than two years, for at least ten hours per week], on the function of the heart in a group of normal active Egyptian power and endurance athletes. The study had been conducted in the Cardiology Department, Suez Canal University Hospital. The study had been conducted on 27 Power active athletes, 27 Endurance active athletes and 27 control subjects in Ismailia Governorate Clubs. The following parameters were recorded: Weight in kilogram, height in centimeter, body surface area [BSA], blood pressure and pulse. Echocardiographic parameters as Left ventricular end systolic and diastolic indexes, Left ventricular end systolic and diastolic volumes, Stroke volume, Cardiac output, Ejection fraction and E/A ratio. Global myocardial performance index [Tei index] was calculated as the sum of both contraction and relaxation isovolumetric periods, divided by the ejection time. The overall mean age of control group is 21.3 +/- 1.4 years, active endurance athletes 22.5 +/- 5.2 years, and for active power athletes 23.6 +/- 3.2 years. Systolic blood pressure was higher in power active athletes [though non-significant]. The heart rate was significantly lower in active athletes rather than in control subjects [p>0.05]. There were significant differences between control subjects and active athletes regarding stroke volume [SV] and cardiac output. Our study revealed that there was no significant difference found with respect to [EF] between active athletes and control subjects. Our study revealed that there was no significant difference exists with respect to [EF%] between Endurance active athletes, power active athletes and controls. Also there existed non-significant difference regarding the global myocardial function assessed by the Tei Index. There was no significant difference between active athletes and control subjects with respect to E/A ratio. But E/A ratio was significantly greater in endurance trained athletes than that in Power trained athletes. It is concluded that despite the striking left ventricular cavity enlargement in athletes there is no evidence of global systolic dysfunction or abnormal diastolic filling pattern. These findings are most consistent with the benign and physiological nature of athletic heart