Right Heart Structure and Function in Lifelong Recreational Endurance Athletes with and without Paroxysmal Atrial Fibrillation.

Background: Healthy young athletes adapt to the increased demands of endurance exercise with symmetric cardiac remodeling. Male veteran endurance athletes have an increased risk for atrial fibrillation (AF), and some athletes seem susceptible to changes mimicking arrhythmogenic cardiomyopathy. Intense exercise puts a disproportionate hemodynamic load on the right-sided heart chambers. Despite this, data describing right heart structure and function in older veteran athletes are scarce. The aim of this study was to investigate structural and functional characteristics of the right heart in veteran athletes with and without AF to contribute to the understanding of exercise-induced cardiac remodeling in this group.

Methods: Three hundred two male participants, of whom 151 were veteran skiers (62 with paroxysmal AF) and 151 were control subjects from the general population (62 with paroxysmal AF), underwent echocardiographic examinations in sinus rhythm to evaluate right atrial (RA) and right ventricular (RV) structure and function. While 87 of the participants had never exercised regularly, 50, 43, and 122 men had practiced regular endurance exercise for 1 to 20, 20 to 40, and >40 years, respectively.

Results: RA volume and RV size increased with cumulative years of exercise (P < .001), with a disproportionate increase in RV size compared with left ventricular (LV) size, regardless of AF status (P < .001). RA and RV function assessed by strain remained similar despite lifelong exposure to endurance exercise. AF was associated with reduced RA strain irrespective of exposure to exercise (P < .001).

Conclusions: RA and RV sizes and RV/LV ratio showed a dose-response relationship with cumulative years of endurance exercise, whereas RA and RV function did not, indicating that increasing RV/LV ratio may represent a physiologic adaptation to prolonged endurance exercise. AF was associated with reduced RA function, regardless of exposure to exercise, suggesting that RA functional parameters are more closely linked to AF than RA size in veteran athletes.