Five of 789 professional athletes infected with COVID-19 were later found to have suffered inflammatory heart disease in the largest study to date on the cardiac impact of the virus in sports.

The study was published in JAMA Cardiology, doctors affiliated with six U.S.-based leagues followed the 789 infected players last year between May and October.

Before returning to play, the athletes underwent three noninvasive tests that tracked heart rhythms, took an ultrasound of their hearts and measured a protein in their blood that can be a signal of heart damage.

Doctors diagnosed five cases of inflammatory heart disease (0.6% of the total), with three cases identified as myocarditis and two as pericarditis.