A family statement read out on CNN on Wednesday said: "Ken Lay passed away early this morning in Aspen. Out of respect for the family we will release no further details at this time."
Pat Worcester, the executive assistant to the CEO at Aspen Valley Hospital, Colorado said Lay was admitted into the emergency room at 3:10am on Wednesday.
Steve Wende, the pastor of the First United Methodist Church of Houston, where Lay lived, said in a statement that Lay died unexpectedly of a "massive coronary."
Wende said Lay and his wife, Linda, were in Aspen, Colorado, for the week "and his death was totally unexpected. Apparently, his heart simply gave out."
Lay was 64 and was convicted in May of six charges of conspiracy and fraud. He was awaiting sentencing along with Enron's former CEO, Jeffrey Skilling, who was convicted on 19 charges of conspiracy, fraud, insider trading and making false statements.
The two were found guilty of setting up an elaborate scheme to deceive investors over Enron's crumbling finances prior to what was at the time the largest corporate bankruptcy in US history.
Their sentencing had been set for October 23.
Lay's early life was a rags to riches story. After being born into a poor Missouri family in 1942, he worked his way up in the business world and founded Enron in the 1980s after the merger of two pipeline companies.
He remained as chief executive except for a brief period in 2001, and then took back the post of CEO until the company filed for bankruptcy later that year.
Lay was a prominent Republican donor and used his vast fortune to garner political power.
He contributed generously to Geroge Bush's presidential campaign in 2000 and was often referred to by the president simply as Kenny Boy.