Endurance Training Leaves Mark on Athletes’ Hearts

TOPLINE:

Myocardial fibrosis was detected in 47.2% of asymptomatic male veteran endurance athletes and was associated with a nearly fivefold increased risk for ventricular arrhythmia, a study found. During follow-up, 21.7% of athletes experienced episodes of ventricular arrhythmia, with 2.8% developing sustained ventricular tachycardia.

METHODOLOGY:

• Researchers conducted a prospective observational cohort study involving 106 asymptomatic male competitive cyclists and triathletes aged 50 years or older who had exercised at least 10 h/wk for more than 15 years.
• Men were excluded from the study if they had been diagnosed with a preexisting cardiovascular condition.
• Participants underwent cardiovascular MRI, stress perfusion late gadolinium enhancement, exercise testing, and implantable loop recorder implantation for ventricular arrhythmia detection.
• Analysis included a median follow-up period of 720 days, during which participants were monitored for the primary endpoint of incident ventricular arrhythmia.

TAKEAWAY:

• Cardiac MRI found nearly half (47.2%) of athletes in the study had focal myocardial fibrosis (all nonischemic distribution), predominantly affecting the basal inferolateral left ventricular segment.
• Myocardial fibrosis was independently associated with an increased risk for ventricular arrhythmia (hazard ratio [HR], 4.7; 95% CI, 1.8-12.8; P = .002), even after adjusting for left ventricular end-diastolic volume (HR, 4.7; 95% CI, 1.7-12.7; P = .002).
• Athletes with ventricular arrhythmia exhibited significantly greater left ventricular end-diastolic volume (113 ± 18 mL/m² vs 106 ± 13 mL/m²; P = .04) and native T1 times (1252 ± 46 ms vs 1241 ± 39 ms; P = .03).
• Athletes with fibrosis showed a higher prevalence of premature ventricular contractions during exercise testing than those without (71.4% vs 42%; P = .003), with more atypical features (46.9% vs 18%; P = .002).

IN PRACTICE:

“In this prospective study, myocardial fibrosis on cardiovascular magnetic resonance imaging was independently associated with the risk of ventricular arrhythmia in healthy, asymptomatic veteran male endurance athletes,” the researchers of the study reported. “Other predictors of ventricular arrhythmia included left ventricular dilatation, and exercise-induced premature ventricular contractions. As the incidence of ventricular arrhythmia may be associated with sudden cardiac arrest, the presence of myocardial fibrosis, left ventricular dilatation and exercise-induced premature ventricular contractions may play a role in indirectly predicting the risk of sudden cardiac arrest among certain athletes. However, further studies are needed to confirm this and to determine whether athletes with myocardial fibrosis on cardiovascular magnetic resonance have a concealed form of cardiomyopathy.”

SOURCE:

The study was led by Wasim Javed, PhD, of the Leeds Institute of Cardiovascular and Metabolic Medicine, in the United Kingdom. It was published online July 17 in Circulation: Cardiovascular Imaging.

LIMITATIONS:

The researchers acknowledged several key limitations of their study, including the limited sample size and highly selected nature of participants. The findings may not be generalizable to other groups, including female and non-White athletes. The single-lead nature of the implantable loop recorders did not allow for localization of ventricular arrhythmia to confirm its origin from the site of myocardial fibrosis. The endpoint of ventricular arrhythmia only indirectly correlates with sudden cardiac death, requiring further study for clinical implications.

DISCLOSURES:

This research was supported by the National Institute for Health and Care Research Leeds Biomedical Research Centre, the British Heart Foundation, and the Leeds Clinical Research Facility.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.