Kalas, who died Monday, had high blood pressure and suffered from atherosclerotic cardiovascular disease, a spokeswoman at the Washington D.C. chief medical examiner's office said. The disease, in which plaque buildup restricts blood flow in arteries, is a major cause of heart attacks and strokes.
Known for his signature "Outta here!" home run calls, Kalas died after collapsing in the broadcast booth before the Phillies' 9-8 victory over the Washington Nationals. He was 73.
Kalas is survived by his wife and three sons, including one -- Todd -- who is a broadcaster for the Tampa Bay Rays.