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

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.

LAY SUMMARY: We studied young and middle-aged male endurance athletes and non-athletes using heart magnetic resonance imaging scans and 24 h heart rhythm monitoring to evaluate scarring of the heart muscle, pumping function, and abnormal heart rhythms.Scarring of the heart muscle is relatively common in middle-aged athletes, but rare in the young. About one in five middle-aged athletes showed a particular 'non-hinge-point' pattern of scar tissue, which was rare in young athletes and also less frequent in middle-aged non-athletic individuals.Non-hinge-point scar was linked with more frequent abnormal heart rhythms. Athletes with this pattern of scar more frequently had premature ventricular beats (extra beats originating from the heart's lower chambers).