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-19 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-19 and how serious those heart issues might 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 might 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-19 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 the total 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-19 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-19 -- might have developed myocarditis. The Gainesville Sun reported that month that he had been diagnosed with myocarditis, but his family issued a statement in February saying the incident was not COVID-related and declined to release additional details.
Consequences Still Unclear
Doctors still don't know how significant those MRI findings of myocarditis might be for athletes. Tests looking for rare medical events often generate more false positives than true positives. And without comparing the results with those of athletes who didn't have COVID-19, it is hard to determine which changes to attribute to the virus and which might just be an effect of athletic training or other causes.
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-19, 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-19, 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."
Falling Through the Cracks
Those screening guidelines, published by a group of leading sports cardiologists in October, call for cardiac tests only for athletes with moderate or severe COVID-19 symptoms. Athletes with asymptomatic cases or those with mild symptoms that have gone away can return to play without the additional testing. The National Federation of State High School Associations and the American Medical Society for Sports Medicine have put out similar guidelines for high school athletes.
But that approach would not flag players such as Demi Washington.
Washington, a 19-year-old sophomore on Vanderbilt's women's basketball team, had a rather mild case of COVID-19. She had shared a meal with two teammates, one of whom later turned out to be infected. Seven days into a two-week quarantine in a hotel off campus, Washington also tested positive, and she had to isolate with a stuffy nose for an additional 10 days. She waited for her symptoms to get worse, but they never did.
"It felt like allergies," she said.
But when her symptoms cleared and she returned to practice, the university required her to undergo several tests to ensure the virus had not affected her heart. The initial tests raised no concerns. An MRI, though, showed acute myocarditis.
Her season was over, but, more importantly, Washington, an athlete in prime physical condition, faced the possibility of losing her life. She learned about Hank Gathers, a 23-year-old Loyola Marymount basketball star who collapsed during a game in 1990 and died within hours. His autopsy confirmed an enlarged heart and myocarditis.
"That really put me on the edge of my seat," Washington said. "I was like, 'OK, I have to take this seriously, because I don't want to end up like that.'"
For months, she had to keep her heart rate under 110 beats per minute. Before, she ran 5 miles a day. With the myocarditis diagnosis, she had to wear a heart monitor, and even a brisk walk could push her above that threshold.
"One time I was walking to the gym and I might have been walking a little fast," Washington recalled. "My chest got really, really tight."
By mid-January, however, another MRI showed the inflammation had cleared, and she has since resumed working out.
"I'm so grateful that Vanderbilt does the MRI, because without it, there's no telling what could have happened," she said.
She wondered how many other athletes have been playing with myocarditis and didn't know it.
Cases like Washington's raise questions about how aggressively to screen. Her condition was found only because Vanderbilt took a much more conservative approach than that recommended by current guidelines: It screened all athletes with cardiac MRIs after they had COVID-19, regardless of the severity of their symptoms or their initial cardiac tests.
Of the 59 athletes screened post-COVID, the university found two with signs of myocarditis. That's just over 3%.
"Is the current rate of myocarditis that we're seeing high enough to warrant ongoing cardiovascular screening?" asked Dr. Daniel Clark, a Vanderbilt sports cardiologist and lead author of an analysis of the school's screening efforts. "Five percent is too much to ignore, in my opinion, but what is our societal threshold for not screening highly competitive athletes for myocarditis?"
Even though myocarditis is rare, studies have found that non-COVID-related myocarditis causes up to 9% of sudden cardiac deaths among athletes, said Dr. Jonathan Drezner, director of the University of Washington Medicine Center for Sports Cardiology, who advises the NCAA on cardiac issues. Thus COVID-19 adds a new risk. The NCAA alone reports more than 480,000 athletes. To provide a sense of scale: If all of them got COVID-19 and even 1% were at risk of heart problems, that's 4,800 athletes.
Waiting for More Data
Doctors are now waiting for the release of data pooled from thousands of college athletes screened after having COVID-19 last year. The American Heart Association and the American Medical Society for Sports Medicine have created a national registry to track COVID-19 cases and heart disease in NCAA athletes, with more than 3,000 athletes enrolled, while the Big Ten conference is running its own registry.
That registry data might eventually help parse who is most at risk for heart complications, target who needs to be screened and improve the reliability of the tests. Doctors might discover that some symptoms are better indicators of risk than others. And down the road, genetic testing or other types of tests could identify who is most vulnerable.
But will smaller schools have the resources and know-how to screen all their athletes?
"How about all the junior colleges, all the Division III programs, the Division II programs?" Martinez said. "A lot of them are saying, 'Look, forget it. If we have do all this extra testing, we can't do it.'"
He said the new pro sports data should reassure those colleges and even high schools because the vast majority of young, healthy athletes who contract COVID-19 generally have mild or asymptomatic infections and won't need further testing.
The same guidelines apply to recreational athletes. Those with mild or asymptomatic COVID-19 can slowly resume exercising once their symptoms resolve without much concern. Those with moderate or severe cases should talk to their doctors before returning to sports.
Concerns for Small Schools
Large, wealthy universities such as Vanderbilt have cutting-edge medical facilities with the resources and expertise to properly interpret cardiac MRIs. Smaller schools could struggle to get their athletes screened.
"There's only a small number of centers around the country that have the true expertise to be able to effectively do cardiac MRIs on athletes," said Dr. Dermot Phelan, a sports cardiologist with Atrium Health in Charlotte, North Carolina. "And the reality is that those systems are already stretched trying to deal with normal clinical data. If we were to add a huge population of athletes on top of that, I think we would stretch the medical system significantly."
Some schools with limited resources for testing could decide to bench athletes recovering from moderate or severe COVID-19 rather than risk a devastating event. Others could allow athletes to resume playing once they've recovered and monitor them for signs of cardiac complications. Many NCAA schools added automated external defibrillators after Gathers' death in case an athlete collapses during a game or practice.
"You think about all the 100,000 high school athletes out there whose parents are concerned: Do they even have access to anyone who knows something about this? On the other hand, they're younger people who don't get really sick with COVID," said Dr. James Udelson, a cardiologist with Tufts Medical Center in Boston. "There's a concern about how much we don't know."
Some schools might also worry about the liability of allowing players to return after a COVID-19 infection if they can't get the proper cardiac screening.
"No matter what precautions a college or university takes in that regard, they can always be sued," said Richard Giller, an attorney with the Pillsbury Winthrop Shaw Pittman law firm in Los Angeles. "The real question is, do they have liability? I think that's going to depend on a number of factors, not the least of which is who recommended that student-athletes who contracted COVID-19 return to play."
He recommends that colleges not rely solely on doctors affiliated with the university but have student-athletes see their own private physicians to make return-to-play decisions. Teams might also ask players to sign waivers to the effect that they understand that if they return to play after a COVID-19 infection, they might face cardiac complications.
Some colleges asked students to sign waivers absolving the school if a player contracted COVID-19. But the NCAA ruled that schools couldn't make those waivers a requirement to play.
Doctors don't know what might happen over the long run. With barely a year's worth of experience with COVID-19, it's not clear whether the myocarditis seen on MRIs will resolve quickly, or whether there might be lingering effects that cause complications years later.
That leaves many concerned about what we still don't know about COVID-19 and the athlete's heart, as well as the handful of cases that might elude detection.
"You can take a cohort of athletes and put them through every single cardiac test and come out the other end, and one of them will die someday," Phelan said. "The reality is there's nothing we can do to be 100% guaranteed."
Markian Hawryluk is a reporter for KHN. ESPN's Paula Lavigne and Mark Schlabach contributed to this report.
KHN (Kaiser Health News) is a national newsroom that produces in-depth journalism about health issues. Together with Policy Analysis and Polling, KHN is one of the three major operating programs at KFF (Kaiser Family Foundation). KFF is an endowed nonprofit organization providing information on health issues to the nation.