Purpose: To assess cardiac morphologic and functional adaptations in elite triathletes with magnetic resonance (MR) imaging and to compare findings to those in recreationally active control subjects.
Materials and methods: The institutional review board approved the study, and written informed consent was obtained from all subjects. Twenty-six male triathletes (mean age ± standard deviation, 27.9 years ± 3.5; age range, 18-35 years) and 27 nonathletic male control subjects (mean age, 27.3 years ± 3.7; age range, 20-34 years) underwent cardiac MR imaging. Electrocardiographically gated steady-state free-precession cine MR imaging was used to measure indexed left ventricular (LV) and right ventricular (RV) myocardial mass, end-diastolic and end-systolic volumes, stroke volume, ejection fraction (EF), and cardiac index at rest. The ventricular remodeling index, which is indicative of the pattern of cardiac hypertrophy, was calculated. The maximum left atrial (LA) volume was calculated according to the biplane area-length method. Differences between means of athletes and control subjects were assessed by using the Student t test for independent samples.
Results: The atrial and ventricular volume and mass indexes in triathletes were significantly greater than those in control subjects (P < .001). In 25 of the 26 athletes, the LV and RV end-diastolic volumes were greater than the normal ranges reported in the literature for healthy, male, nonathletic control subjects (47-92 mL/m(2) and 55-105 mL/m(2), respectively). There was a strong positive correlation between end-diastolic volume and myocardial mass (P < .01). The mean LV and RV remodeling indexes of the athletes (0.73 g/mL ± 0.1 and 0.22 g/mL ± 0.01, respectively) were similar to those of the control subjects (0.71 g/mL ± 0.1 [P = .290] and 0.22 g/mL ± 0.01 [P = .614], respectively). There was a negative correlation between LA end-systolic volume and heart rate (P < .01).
Conclusion: Changes in cardiac morphologic characteristics and function in elite triathletes, as measured with cardiac MR imaging, reflect a combination of eccentric and concentric remodeling with regulative enlargement of atrial and ventricular chambers. These findings are different from what has been observed in previous studies in other types of elite athletes.