Pennsylvania Lt. Gov. John Fetterman, who won the Democratic nomination for U.S. Senate in May, was diagnosed with cardiomyopathy, a condition that causes the heart muscle to become weakened and enlarged, his doctor disclosed Friday.

The Democrat suffered a stroke in mid-May, just days before winning the nomination for Senate in Pennsylvania, a key swing state in the midterm elections in November. The statement Friday was the first public comment about the lieutenant governor’s condition since being released from the hospital. Fetterman was released more than a week after he suffered a stroke.