RESTING HEART RATE AS THE SENSITIVE MARKER OF THE EARLY LEFT VENTRICULAR REMODELING IN YOUNG TEENAGE FOOTBALLERS
Purpose: Regular physical training is connected to increased vagal tonus, leading to diminished heart rate in professional athletes. The aim of the study was to evaluate correlation of the diminished heart rate and early left ventricle remodeling in adolescent professional footballers.
Methods: 94 teenage footballers were screened by ECG at rest and echocardiography at a tertiary referral cardio centre. They were from national professional football league (at least 7 training hours/week). Control group consisted of 47 age-matched healthy volunteers with sedentary life style (less than 2 training hours/week). All athletes and volunteers from control group had no symptoms, none of them had syncope and physical findings were normal. All the echocardiographic findings were adjusted to BSA (-0.5), while left ventricle mass (LVM) was additionally adjusted to BSA(-1.5). Echocardiographic reference ranges were defined as values of 5-95th centile according to the mean values in both groups. The proportions of the footballers with LV dimensions outside expected ranges were additionally noted. Heart rate frequency and its correlation with echocardiographic parameters (aorta AO, enddyastolic-EDDLV, endsystolic dimension-ESDLV, left atrial dimension-LA, ejection fraction -EF, fraction of shortening - FS and left ventricle wall thickness, left ventricle mass –LVM and left ventricle mass index -LVMI) was compared in these two groups.
Results: None of the players and participants had bradicardia. However, resting heart rate as well as ECG–monitored heart rate before exercise testing were significantly higher in the group of footballers ( 72/min vs. 90/min, p<0.001 and 83/min vs. 89/min, p<0.001). There was a strong correlation between heart rate and all echocardiographic parameters, except left ventricular wall thickness. Our data indicate an early cardiac remodeling, already apparent in preadolescence, even after a short period of training and resting heart rate as an sensitive marker of the early left ventricular remodeling.