Up to 15 percent of university athletes are showing signs of heart inflammation months after contracting COVID-19, Ohio State researchers have found.
A study published in JAMA Cardiology found swelling in the heart muscle of some healthy athletes, possibly brought on by a rare condition called myocarditis, which could be linked to COVID-19 exposure, authors say.
Myocarditis can be fatal - it's responsible for up to 20 percent of sudden cardiac deaths in sports and can be caused by infections.
Athletes with myocarditis are recommended to stop participating in sports for three to six months, to allow the heart to heal.
Researchers took MRI scans of 26 Ohio State University athletes' hearts - all who had previously tested positive for COVID-19 - finding evidence of myocarditis in four of them (15 percent).
Eight additional athletes (30 percent) showed signs of possible injury to cells without evidence of swelling, which may be linked to a COVID-19 infection - although doctors say it's difficult to know for sure.
None of the participants, who played American football, soccer, lacrosse, basketball and track & field, had previous heart conditions before being tested.
The cardiac MRI was carried out from 11 days to two months after each athlete returned a positive COVID-19 test.
When the participants were previously infected, 12 reported mild symptoms such as a fever, sore throat and muscle aches, while the remaining 14 were asymptomatic. All athletes were fully recovered from COVID-19 at the time of being scanned.
Meagan Wasfy, a sports cardiologist at Massachusetts General Hospital, told Science News that it's difficult to broadly apply the study's findings.
Wasfy says there are several limitations to the study. It was a small sample, did not include controls, and did not test participants within the same time interval after contracting the virus.
A myocarditis diagnosis is usually confirmed in combination with other clinical trials such as symptoms, blood test results and high levels of a troponin protein. In the study of 26 athletes, every other finding was deemed normal, except for mild viral symptoms in some athletes.
Saurabh Rajpal, a cardiologist at the Ohio State University Wexner Medical Center, says it will take more research to confirm the study's findings.
Rajpal says young people need to pay close attention to how they feel when they return to exercise. If they experience symptoms like chest pain, shortness of breath or an abnormal heartbeat, he recommends they see a doctor.
The authors plan to conduct a further study, this time planning to compare images of athletes' hearts who did not contract COVID-19, with those who have been infected.