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Myocardial Fibrosis in Triathletes
Study Questions:
What is the significance among triathletes of myocardial fibrosis detected by late gadolinium-enhancement (LGE) on cardiac magnetic resonance (CMR)?
Methods:
A cohort of 83 asymptomatic triathletes training >10 hours per week (age 43 ± 10 years; 65% male) and 36 sedentary controls underwent CMR with assessment of LGE and extracellular volume (ECV). Parameters of physical fitness were measured by spiroergometry (cardiorespiratory stress testing). Lifetime competition results were reported by the athletes.
Results:
LGE CMR revealed focal nonischemic myocardial fibrosis in 9 of 54 (17%) male triathletes (LGE+), but in none of the female triathletes (p < 0.05). LGE+ triathletes had higher peak exercise systolic blood pressure (213 ± 24 mm Hg) compared with LGE− triathletes (194 ± 26 mm Hg; p < 0.05). Left ventricular mass index was higher in LGE+ triathletes (93 ± 7 g/m2) than in LGE− triathletes (84 ± 11 g/m2; p < 0.05). ECV in LGE− myocardium was higher in LGE+ triathletes (26.3 ± 1.8%) than in LGE− triathletes (24.4 ± 2.2%; p < 0.05). LGE+ triathletes completed longer cumulative distances in swimming and cycling races and participated more often in middle and Iron Man distances than did LGE− triathletes. A cycling race distance of >1,880 km completed during competition had the highest accuracy to predict LGE, with an area under the curve value of 0.876 (p < 0.0001), resulting in high sensitivity (89%) and specificity (79%). Multivariate analysis identified peak exercise systolic blood pressure (p < 0.05) and swimming race distance (p < 0.01) as independent predictors of LGE presence.
Conclusions:
Myocardial fibrosis in asymptomatic triathletes was associated with exercise-induced hypertension and longer race distances. The authors concluded that there appears to be a safe upper limit of exercise beyond which exercise may result in myocardial fibrosis.
Perspective:
Myocardial fibrosis detected by LGE has been reported to occur in up to half of asymptomatic athletes. This study finds a correlation between LGE on CMR among triathletes who develop exercise-induced systolic hypertension and triathletes with longer race distances. This study does not provide data suggesting that LGE among triathletes is associated with adverse clinical outcomes.
Clinical Topics: Cardiovascular Care Team, Diabetes and Cardiometabolic Disease, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Prevention, Sports and Exercise Cardiology, Magnetic Resonance Imaging, Exercise, Hypertension, Sports and Exercise and ECG and Stress Testing, Sports and Exercise and Imaging
Keywords: Athletes, Blood Pressure, Cardiomyopathies, Diagnostic Imaging, Exercise Test, Fibrosis, Gadolinium, Hypertension, Magnetic Resonance Imaging, Myocardium, Physical Fitness, Primary Prevention, Sports, Swimming, Systole
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