For sports fans across the country, the resumption of the regular sports calendar has signaled another step toward post-pandemic normality. But for the athletes participating in professional, collegiate, high school or even recreational sports, significant unanswered questions remain about the aftereffects of a COVID infection.
Chief among those is whether the coronavirus can damage their hearts, putting them at risk for lifelong complications and death. Preliminary data from early in the pandemic suggested that as many as 1 in 5 people with COVID-19 could end up with heart inflammation, known as myocarditis, which has been linked to abnormal heart rhythms and sudden cardiac death.
Screening studies conducted by college athletic programs over the past year have generally found lower numbers. But these studies have been too small to provide an accurate measure of how likely athletes are to develop heart problems after COVID, and how serious those heart issues may be.
Without definitive data, concerns arose that returning to play too soon could expose thousands of athletes to serious cardiac complications. On the other hand, if concerns proved overblown, the testing protocols could unfairly keep athletes out of competition and subject them to needless testing and treatment.
“The last thing we want is to miss people that we potentially could have detected, and have that result in bad outcomes — in particular, the sudden death of a young athlete,” said Dr. Matthew Martinez, director of sports cardiology at Atlantic Health’s Morristown Medical Center in New Jersey and an adviser to several professional sports leagues. “But we also need to look at the flip side and the potential negatives of overtesting.”
With millions of Americans playing high school, college, professional or master’s level sports, even a low rate of complications could result in significant numbers of affected athletes. And that could prompt a thorny discussion of how to balance the risk of a small percentage of players who could be in danger against the continuation of sports competition as we know it.
Limited Impact on Pro Sports
Data released from professional sports leagues in early March provided at least some reassurance that the problem may not be as great as initially feared. Pro athletes playing football, men’s and women’s basketball, baseball, soccer and hockey were screened for heart problems before returning from COVID infections. The players underwent an electrical test of their heart rhythms, a blood test that checks for heart damage and an ultrasound exam of their hearts. Out of 789 athletes screened, 30 showed some cardiac abnormality in those initial tests and were referred for a cardiac MRI to provide a better picture of their heart. Five of those, less than 1% of athletes screened, showed inflammation of the heart that sidelined them for the remainder of their seasons.
The researchers compiling the data did not name the players, although some have disclosed their own diagnoses. Boston Red Sox pitcher Eduardo Rodríguez returned to the mound this spring after missing the 2020 season following his COVID and myocarditis diagnoses. Similarly, Buffalo Bills tight end Tommy Sweeney was close to returning from a foot injury when he was diagnosed with myocarditis in November.
In the college ranks, many assumed Keyontae Johnson — a 21-year-old forward on the University of Florida men’s basketball team who collapsed on the court in December, months after contracting COVID — might have developed myocarditis. The Gainesville Sun 
Training significantly changes athletes’ hearts, and what might look concerning in another patient could be perfectly normal for an elite athlete. Many endurance athletes, for example, have larger than average left ventricles and pump out a lower percentage of blood with each contraction. That would be a warning sign for patients who aren’t highly trained athletes.
“You can definitely have what we call the gray zone, where extreme forms of athletic cardiac remodeling can actually look a little bit like pathology,” said Dr. Jonathan Kim, a sports cardiologist at Emory University in Atlanta. “Covid has introduced a new challenge to this. Is it because they’re a cross-country runner or is it because they just had COVID?”
Moreover, myocarditis is generally diagnosed based on symptoms — chest pain, shortness of breath, heart muscle weakness or electrical dysfunction — and then confirmed by MRI. It isn’t clear whether MRI findings that look like myocarditis in the absence of those symptoms are just as concerning.
“They have normal physical exams. They have normal cardiograms. Nothing else is going on,” said Dr. Robert Bonow, a cardiologist at Northwestern University and editor of JAMA Cardiology. “But when you order an MRI as part of a research study, you start seeing very subtle changes, because the MRI is very sensitive.”
Were they finding “abnormalities” simply because they were looking? Even in patients who die of COVID, the rate of myocarditis is very low, Bonow said.
“So what’s going on with the athletes? Is it something related to the fact that they had an infection, or is it something which is very nonspecific, related to covid but not damage to the heart?” he said. “There’s still a great deal of uncertainty.”
Sports cardiologists involved in the pro sports data collection and in writing screening guidelines for athletes said the fact that players were able to resume their seasons without serious heart complications suggests the initial concern was overblown. Of the players who had mild or asymptomatic cases of COVID, none was ultimately found to have myocarditis, and none experienced ongoing heart complications through 2020. Many completed their 2020 season and have already started their next one.
“We overcalled it,” Martinez said. “It shows what our guidelines reflected: The prevalence of cardiac disease in this condition is unusual in the athletic population…”