He was 82.
Clark had undergone an outpatient procedure last night and was at LA's St. John's hospital at the time of his heart attack.
Famed host of such shows as American Bandstand and Pyramid, the veteran TV producer and personality was forced to retire from hosting his long-running New Year's Rockin' Eve special in 2005 after he suffered a serious stroke.
Clark leaves behind his third wife, Kari Wigton, and three children from previous marriages.
[photo via AP]