Male triathletes, who participate in multiple-stage competition, including swimming, cycling and running, face a higher risk of a harmful heart condition, a study has found. The increased risk, which was not evident in female triathletes, was directly associated with the athletes’ amount of exercise, according to the research being presented this week at the annual meeting of the Radiological Society of North America (RSNA). Myocardial fibrosis is scarring of the heart.
It usually affects the pumping chambers, also known as the ventricles. The condition might progress to heart failure.
“The clinical relevance of these scars is currently unclear. However, they might be a foundation for future heart failure and arrhythmia,” said lead author Jitka Starekova, from the University Medical Center Hamburg-Eppendorf in Germany. Researchers studied a group of triathletes, including 55 men (average age 44) and 30 women (average age 43). The study group underwent cardiac MRI exams with the contrast agent gadolinium, which is taken up by both normal and injured heart muscle tissue. Gadolinium washes out quickly in normal heart tissue, however much more slowly in scarred tissue, revealing a difference in contrast between normal and injured heart muscle after approximately 10 minutes.This phenomenon, known as late gadolinium enhancement, is a useful tool for detection of myocardial fibrosis. Evidence of myocardial fibrosis was apparent in the left ventricle – the heart’s main pumping chamber – in 10 of 55 of the men, or 18 per cent, but in none of the women.There are several possible factors for the link between the amount of exercise and the risk of myocardial fibrosis, according to Starekova. Higher exercise-induced systolic blood pressure may result in greater myocardial mass, she said, and more exercise might expose the athlete to a higher risk of myocarditis, or inflammation of the heart muscle. These factors, in combination with repeatedly increased stress of the left ventricular wall due to exercise, could injure the heart muscle.