Author(s): AGGOKABO, O.P., JOHNSON, C., MORRISON, B., ASHLEY, E., FROLELICHER, V., HADDAD, F., SHAVE, R., SHANTSILA, A., SPRUNG, V., LIP, G.Y.H., GEORGE, K., OXBOROUGH, D., Institution: LIVERPOOL JOHN MOORES UNIVERSITY, Country: UNITED KINGDOM, Abstract-ID: 1959

INTRODUCTION:
Undertaking aerobic exercise training to meet World Health Organisation guidelines is associated with positive cardiovascular benefits. There is however, evidence suggesting that very high volumes of endurance exercise training may be associated with adverse cardiac remodelling and increased prevalence of arrhythmia (including atrial fibrillation [AF]). Quantifying the burden of arrhythmia and its association with lifetime training exposure and cardiac remodelling in highly trained ultra-endurance athletes was the focus of the present study.
METHODS:
20 male (age 48 ± 10 years) and 15 female (age 47 ± 12 years) asymptomatic, healthy ultrarunners who secured a place at the 2022 Western States endurance race or were attending the pre-race training camp (California, USA), were recruited. A continuous electrocardiogram (ECG) monitor was worn for one week prior to the race/training camp providing incidence of premature atrial contractions (PACs), premature ventricular contractions (PVCs) and number of episodes of AF. A questionnaire captured lifetime training volume (MET-hr) and lifetime running miles. A full transthoracic echocardiogram was undertaken 24-48 hours before the race/training run. LV structure was defined by LV mass (LVM), end diastolic volume (EDV) and mean wall thickness (MWT) whilst function was determined by ejection fraction (EF) and global longitudinal strain (GLS). Left atrial (LA) structured was defined by LA volume (LAV). Pearsons correlation determined the association between arrhythmia burden and (1) cardiac structure and function, and (2) training exposure.
RESULTS:
There was a 0.6 ± 0.8 (0-3.4%) and 0.7 ± 0.7 (0-2.6%) PAC and PVC burden, respectively. There were no episodes of AF. A weak but significant correlation was apparent between PVC burden and LVEDV (r= 0.376; P=0.044). There were no significant associations between arrhythmia burden and indices of cardiac structure and function. There were significant correlations for PAC burden (%) with lifetime training volume (MET-hr) (r=0.506 P=0.005), and lifetime running miles (r=0.367 P=0.046). PVC burden did not significantly correlate with measures of lifetime training exposure.
CONCLUSION:
In a unique cohort of asymptomatic ultra-endurance athletes with significant lifetime endurance training exposure, we observed a relatively low overall arrhythmic burden and lack of AF. We observed an association between PVC burden and LV size suggesting some level of linkage between cardiac remodelling and ventricular arrhythmia burden that requires further evaluation. The association between atrial arrhythmia burden and measures of lifetime exercise exposure maybe a pre-cursor to the development of AF that could be a focus of future clinical evaluation.