Cardiac anatomy and diastolic filling in professional road cyclists

In the literature two divergent types of exercise-induced cardiac hypertrophy have been described: isotonic exercise induced eccentric hypertrophy with proportional increase in end-diastolic left ventricular dimension and wall thickness and isometric exercise induced concentric hypertrophy with normal end-diastolic left ventricular dimension but increased wall thickness. Using echocardiography, cardiac anatomy and diastolic filling were studied in 26 professional road cyclists. Compared to 21 control subjects, matched according to age, sex and morphometry the athletes had significantly larger left atrial dimension [41.3 (SD 4.8) vs 36.6 (SD 4.5) mm], left ventricular dimension [56.0 (SD 3.8) vs 53.2 (SD 4.7) mm], end-diastolic septum thickness [11.1 (SD 2.5) vs 8.4 (SD 1.9) mm], end-diastolic posterior wall thickness [11.6 (SD 2.2) vs 8.4 (SD 1.5) mm] and left ventricular mass index [170.4 (SD 40.6) vs 107.0 (SD 27.7) g.m-2]. We concluded that the hypertrophy in the road cyclists was of the mixed type (concentric-eccentric) with an increase in the internal dimension of the left ventricle and an even larger increase in the thickness of the ventricular walls. Diastolic filling however was similar in the athletes and control subjects. No correlations were found between the left ventricular mass index and diastolic filling parameters. We concluded therefore that professional road cycling causes mixed cardiac hypertrophy without diastolic filling abnormalities and can therefore be considered benign.