Lay, 64, was admitted to the Aspen Valley Hospital late Tuesday suffering from a massive coronary, the TV station reported.
Physicians said Lay's heart simply "gave out" and the death was unexpected.
Lay was found guilty in May on six counts of conspiracy to commit securities and wire fraud in a case born from one of the biggest business scandals in U.S. history. His sentencing had been set for this fall.
At its peak, in 2001, Enron was one of the world's most lucartive and massive energy trading companies. But deceptive accounting sparked a massive sale of Enron stock late that year, forcing the company into bankruptcy and into the arms of federal prosecutors. A number of top executives have been convicted or pled guilty in the subsequent investigations.