Non-ischaemic fibrosis in male veteran endurance athletes: mechanisms and association with premature ventricular beats

Purpose: Left ventricular fibrosis can be identified by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) in some veteran athletes. We aimed to investigate prevalence of ventricular fibrosis in veteran athletes and its association with cardiac arrhythmia. Methods: Fifty asymptomatic male endurance athletes (inclusion criteria: age ≥50, >10 hours/week training for >15 years) and 26 matched controls were recruited. They underwent CMR imaging including volumetric analysis, bright blood (BB) and dark blood (DB) LGE, motion corrected (MOCO) quantitative stress and rest perfusion and T1/T2/extracellular volume mapping. Athletes underwent 12-lead electrocardiogram (ECG) and 24-hour ECG. Results: Myocardial fibrosis was identified in 24/50 (48%) athletes. All fibrosis was mid-myocardial in the basal-lateral wall of the left ventricle. Blood pressure was reduced in athletes without fibrosis compared to controls, a trend not seen in athletes with fibrosis. Fibrotic areas compared to healthy myocardium had longer T2 time (44±4 vs 40±2ms, p<0.0001), lower rest myocardial blood flow (MBF, 0.5±0.1 vs 0.6± 0.1ml/g/min, p<0.0001) but no difference in stress MBF. On 24-hour ECG monitoring, athletes with fibrosis had a greater burden of premature ventricular beats (0.3±0.6 vs 0.05±0.2%, p=0.03), with higher prevalence of ventricular couplets and triplets (33 vs 8%, p=0.02). Conclusion: In veteran endurance athletes, myocardial fibrosis is a common finding. Possible mechanisms for fibrosis include inflammation and blood pressure. Presence of myocardial fibrosis is associated with an increased burden of ventricular ectopy. Further studies are needed to establish whether fibrosis increases risk of malignant arrhythmic events.