Cardiac MRI scans revealed that roughly a third of Big Ten athletes who tested positive for the coronavirus appear to have myocarditis, according to Penn State’s director of athletic medicine.

The sobering comment by Wayne Sebastianelli, the school’s director of athletic medicine, came Monday as pressure for the conference to play football this fall came from President Trump, fans and parents.

“When we looked at our COVID-positive athletes, whether they were symptomatic or not, 30 to roughly 35 percent of their heart muscles (are) inflamed,” Sebastianelli said during a State College Area school board of directors meeting. “And we really just don’t know what to do with it right now. It’s still very early in the infection. Some of that has led to the Pac-12 and the Big Ten’s decision to sort of put a hiatus on what’s happening.”

Myocarditis is an inflammation of the heart muscle that can lead to arrhythmia, cardiac arrest and death, especially in a person who doesn’t know they have it and performs rigorous exercise. Cardiovascular experts are becoming increasingly aware that COVID-19 can affect the heart and urge cardiac screening for athletes who are recovering from the virus. Two high-level athletes – Boston Red Sox pitcher Eduardo Rodriguez and Indiana offensive lineman Brady Feeney – made headlines when they experienced heart issues. Myocarditis causes about 75 deaths per year in athletes from 13 to 25, according to the Myocarditis Foundation.

“You could have a very high-level athlete who’s got a very superior VO2 max and cardiac output who gets infected with COVID and can drop his or her VO2 max (also known as maximal oxygen uptake) and cardiac output just by 10 percent, and that could make them go from elite status to average status,” Sebastianelli said. “We don’t know that. We don’t know how long that’s going to last. What we have seen is when people have been studied with cardiac MRI scans – symptomatic and asymptomatic COVID infections – is a level of inflammation in cardiac muscle that just is alarming.”

There were no details on the players or schools involved, but the conference’s 14 schools are in Nebraska, Minnesota, Iowa, Wisconsin, Illinois, Michigan, Indiana, Ohio, Pennsylvania, New Jersey and Maryland. Despite the economic consequences that will ensue in each place with no fall football seasons, presidents and chancellors from each school – and not Commissioner Kevin Warren – voted 11-3 not to play.

In an open letter last month, Warren wrote that the decision was “based on sound feedback, guidance and advice from medical experts” and mentioned myocarditis as a topic in meetings of presidents, chancellors, athletic directors and health advisory board members. Warren wrote that there is “simply too much we do not know about this virus.”

The Big Ten announced its decision to postpone the fall sports season on Aug. 11.