Myocardial fibrosis and its relationship with ventricular arrhythmias and reduced ventricular systolic function in young and veteran endurance athletes

Abstract

Aims The prevalence of ventricular fibrosis and its association with ventricular arrhythmias (VAs) and reduced ventricular systolic function in endurance athletes remains unclear. Methods and results We evaluated 296 young [median age 19 (17-22)] and 138 middle-aged [56 (50-60)] male endurance athletes, alongside 66 middle-aged non-athletic controls [54 (49-60)], all without known cardiac disease. Cardiac magnetic resonance imaging assessed myocardial fibrosis and biventricular function. Twenty-four-hour Holter monitoring was used to quantify VAs. Non-hinge-point fibrosis was more prevalent in middle-aged athletes compared with young athletes (20 vs. 3%, P < 0.001) and middle-aged controls (20 vs. 9%, P = 0.045), while hinge-point fibrosis did not differ. Reduced left ventricular ejection fraction and/or right ventricular ejection fraction was more frequent in middle-aged athletes than controls (23 vs. 8%, P = 0.009), but similar to young athletes (23 vs. 22%, P = 0.906). Middle-aged athletes had a higher prevalence of non-sustained ventricular tachycardia (8 vs. 2%, P = 0.006), >100 premature ventricular complexes/24 h (13 vs. 5%, P = 0.004), multifocal ventricular ectopy (11 vs. 4%, P = 0.003), and complex ventricular ectopy (25 vs. 10%, P < 0.001) compared with young athletes, with no significant differences compared with controls. Non-hinge-point fibrosis increased the odds of a higher burden of unifocal and multifocal ventricular ectopy, but not of reduced systolic function. Conclusion Middle-aged athletes more frequently exhibit myocardial fibrosis than young athletes and middle-aged non-athletes. Non-hinge-point fibrosis is present in up to one-fifth of middle-aged athletes and predictive of a higher burden of both unifocal and multifocal ventricular ectopy. Reduced systolic function is more prevalent in athletes and not predicted by fibrosis. [GRAPHICS]