Abstract 4145828: The Interplay Between Exercise Load, Myocardial fibrosis, Ventricular Systolic Dysfunction and Ventricular Arrhythmias

Background: An increased prevalence of myocardial ventricular fibrosis, ventricular dysfunction and arrhythmias has been reported amongst highly trained endurance athletes, but trials investigating these adverse phenotypes in adequately sized and accurately phenotyped cohorts are largely lacking. We aimed to define the prevalence of ventricular fibrosis, ventricular systolic dysfunction, arrhythmia and their interplay in healthy endurance athletes. Methods: We analysed a male cohort of 244 young elite endurance athletes (20yr), 134 middle-aged recreational athletes (56yr) and 65 middle-aged non-athletic controls (55yr). CMR assessed for non-hinge point and hinge point late gadolinium enhancement (NH-LGE and H-LGE) and LVEF and RVEF. 24-hour Holter was performed to assess ventricular arrhythmia. Complex arrhythmia was defined as couplets, triplets and NSVT. Exercise load was based on questionnaires. Multiple logistic regression assessed the relationship between exercise load, LGE, ventricular systolic dysfunction and ventricular arrhythmia. Results: Middle-aged athletes had more NH-LGE (19.4% vs 9.2% vs 4.5%, p<0.001) and H-LGE (29.9% vs 13.8% vs 15.6%, p=0.002) than middle-aged controls and young athletes respectively. Lifetime hours of endurance exercise and age increased the odds of NH-LGE (OR 1.034, 95% CI 1.001-1.069, p=0.044 and OR 1.032, 95% CI 1.006-1.058, p=0.014). A LVEF<50% and/or RVEF<45% was more prevalent in middle-aged and young athletes compared to controls (23.1% % vs 20.5% vs 7.7%, p=0.029). A higher lifetime training load increased the odds of RVEF<45% (OR 1.059, 95% CI 1.014-1.105, p=0.009). LGE did not predict LVEF>50% or RVEF<45%. Both complex arrhythmia and a burden of >0.1% VPB were more prevalent in middle-aged athletes compared to young athletes but not compared to controls (26.1% vs 9.8% vs 12.3%, p<0.001 and 13.6% vs 4.9% vs 7.7%, p=0.012 respectively). NH-LGE and RVEF<45% increased the odds of VPB burden >0.1%. (OR 3.845, 95% CI 1.465-10.089, p=0.006 and OR 5.230, 95% CI 1.698-16.106, p=0.004 respectively). Conclusion: NH-LGE is associated with exercise load and more prevalent in middle-aged athletes compared to younger athletes and age-matched controls. When present, LGE is not associated with a reduced ventricular function. On the other hand, NH-LGE and reduced RVEF are risk factors for increased ventricular ectopic burden and middle-aged athletes show significantly more complex arrhythmia compared to younger athletes.