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.”
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 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.