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Study Finds Less Than 1% of Professional Athletes Developed Inflammatory Heart Disease after COVID-19

Professional sports leagues extensively tested COVID-positive athletes to learn more about myocarditis risks.

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A group of sports cardiologists delivered promising results on Thursday, March 4 that show that the risk for inflammatory heart disease in athletes diagnosed with COVID-19 is low. 

The study, published in JAMA Cardiology, aims to answer a question cardiologists and athletes have had since the pandemic began: What can athletes do to mitigate the risk of myocarditis after COVID-19?

The previous return-to-play guidelines put out by the American College of Cardiology Sports and Exercise was meant to fill a temporary void while data was being collected. As Dr. Jonathan Kim, a co-author on the ACC’s return-to-play guidelines told Women’s Running in May of 2020, that kind of data collection takes time. “You obviously have to build up the numbers and as fast as we work on that, these athletes are coming to our clinics now and need guidance,” he said.

This study—authored by a cohort of 16 people affiliated with six major North American sports organizations, universities, and hospitals—backs up what the ACC put forth in May and then amended in October. 

In total they looked at 789 professional athletes from the National Hockey League, Major League Soccer, Major League Baseball, National Football League, National Basketball Association, and Women’s National Basketball Association. 

All of the included pro sports groups implemented precautionary cardiac screening for any player that tested positive for COVID-19 from May 2020 through October 2020. Severity of illness ranged from 58% symptomatic to 42% asymptomatic or minimally symptomatic.

If they tested positive, athletes had to complete troponin testing (a blood test that helps detect heart injury), electrocardiogram (records the electrical signals that make up a heartbeat), and resting echocardiogram (an ultrasound that looks at the structure and function of the heart). If any of those tests came back with concerning results they were referred for further testing. 

Only 30 of the athletes were referred for further testing and of those, five showed signs of inflammatory heart disease. Three were diagnosed with myocarditis and two were diagnosed with pericarditis, which is when the tissue surrounding the heart becomes inflamed. That accounts for less than 1% of the athletes studied. 

Myocarditis can be very serious for athletes, but especially runners. “For endurance athletes, the presence of myocarditis is a risk for dangerous arrhythmias that could lead to a cardiac emergency,” says Dr. David Engel, a cardiologist at Columbia University Irving Medical Center and co-author of the study. This is because high heart rates and high myocardial oxygen demand can trigger the arrhythmias, he adds.

The authors concluded that the more serious the symptoms of COVID-19, the greater the risk for cardiac injury. If you have more serious symptoms, you should return to running cautiously to avoid developing myocarditis or pericarditis. For people who are asymptomatic or have a mild case, it’s safe to return to activity after self-isolating per CDC guidelines.

Like nearly everything else with this virus, there is more research to be done. According to Dr. Engel, the pro leagues are continuing research and conducting follow-ups. “We need to see if the athletes who were found to have cardiac inflammation in the early post-viral illness period resolves or if the inflammation leaves any scarring in the heart,” he says. They also want to confirm that those who had normal cardiac function initially don’t develop an inflammatory heart disease later on.

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