Scar tissue in the heart—myocardial fibrosis—may be associated with abnormal heart rhythms among healthy, long-time male endurance athletes aged 50 years or older, potentially increasing their risk of sudden cardiac death, as per the findings of a small study published recently in Circulation: Cardiovascular Imaging.
“Dangerous heart rhythms during sport are thankfully rare,” said senior study author Peter Swoboda (University of Leeds, Leeds, UK). “In certain highly trained athletes—particularly as they get older—it is possible to identify scarred heart tissue via magnetic resonance imaging. We wanted to investigate whether dangerous heart rhythms in endurance athletes might be caused by heart scarring. Our main aim was to help endurance athletes continue to participate safely in sports, particularly as they get older.”
Myocardial fibrosis has previously been linked to irregular heartbeats; however, the way in which it affects otherwise healthy endurance athletes remains unclear. As such, researchers devised the VENTOUX study—a name inspired by a famous mountain climb in the Tour de France cycling race. They followed 106 male cyclists and triathletes aged 50 years or older from sporting organisations in the UK who had no symptoms of heart disease. All of these athletes had trained for at least 10 hours per week over a period of 15 years or more.
The participants underwent cardiovascular magnetic resonance (CMR) imaging and received an electrocardiogram (ECG) recorder implanted under the skin of their chest to record their heartbeats for two years.
During an average follow-up of two years, researchers found that almost half of the athletes (47.2%) showed signs of scarring on the left ventricle of the heart, and about 3% had sustained, potentially dangerous fast heart rates originating in the lower chambers of the heart—ventricular tachycardia—while 19% experienced shorter bursts of rapid heartbeats.
Any participant who developed a potentially harmful heart rhythm was contacted urgently to assess symptoms and advised to seek independent medical attention.
“We did not expect the association between scarring and dangerous rhythms to be this strong,” Swoboda noted. “Similar findings have been reported in patients with heart muscle disease; however, we did not expect this in healthy performance athletes.”
Swoboda urged any athlete who experiences chest pain, dizziness or palpitations during activity to seek treatment and also advised that “it’s important that everyone involved in sports knows CPR [cardiopulmonary resuscitation] and how to use an automated external defibrillator”.
Although the annual incidence of sudden cardiac death during sports varies among studies, the annual rate of abnormal heart rhythms detected in this study were considerably higher than rates among the general population, the researchers also stated.
They concede that their study has several limitations, including its small number of very select participants, and the fact its findings may not apply to people who were not represented in the study: women, non-athletes and non-European cyclists. In addition, the findings could not differentiate whether the cardiac scarring itself was the cause of irregular heart rhythms or if it was a marker for a separate underlying process. Future research will look to examine women, the authors commented.
