P-wave morphology is unaffected by training-induced biatrial dilatation: a prospective, longitudinal study in healthy athletes.

Biatrial enlargement is common in athletes with a further increase occurring after training. P-wave morphology seems to be unaffected by atrial size, however longitudinal data are not available. This study aimed to prospectively investigate whether exercise-induced increase in biatrial size corresponds to electrical changes on 12-lead ECG. Thirty-five athletes were evaluated at the beginning of the training and after 6 months by ECG and standard and speckle-tracking echocardiography. Twenty-three sedentary subjects served as controls. Athletes had greater left atrial (LA) and right atrial (RA) size compared with controls (20.7 ± 4.7 vs. 27.1 ± 6.6 and 17.3 ± 3.8 vs. 23.4 ± 6.3 mL/m2, respectively, p < 0.0001). After 6 months, a further increase in LA and RA size was observed (p < 0.0001 and p = 0.002, respectively). Neither athletes nor controls fulfilled the ECG criteria for RA enlargement and no differences were found for LA enlargement criteria between athletes and controls (2/35, 6% vs. 0/23, 0%, p = 0.23). This percentage remained unchanged after training. Biatrial stiffness remained normal in athletes also after training. Training causes an increase in biatrial volumes, with normal filling pressures and normal stiffness. These changes in atrial morphology are not associated with respective electrical changes, suggesting that P-wave morphology is unaffected by training-induced biatrial dilatation in young healthy athletes.