CLEMSON -- Former Clemson football star Gaines Adams died Sunday morning in his hometown of Greenwood.
Greenwood County coroner Jim Coursey said Adams, 26, was dead upon arrival at the Self Regional Memorial Hospital emergency room.
An autopsy performed on Sunday indicated the former All-American player died of cardiac arrest caused by an enlarged heart. Drug use isn't suspected in Adams' death, according to reports, though toxicology tests are being run.
According to an NFL.com report, Adams' girlfriend called for an ambulance Sunday morning after Adams was suffering from what Coursey called "health issues." Adams' family was unaware of his enlarged heart condition
Adams, one of three players in Clemson history to be named a unanimous All-American, was the fourth overall pick in the 2007 NFL Draft by Tampa Bay.
He was traded from Tampa Bay to Chicago this season.
Former Clemson coach Tommy Bowden said he was "shocked and saddened" when hearing the news Sunday.
"When I heard the news I thought it was his father because he has the same name," Bowden said. "I just couldn't believe it was Gaines.
"I will always remember the smile he had on his face and I will always remember his patience. He showed his patience when he came back for his senior year and could have gone pro after the 2005 season. This is a great loss and our prayers go out to his family."
Clemson coach Dabo Swinney was the Tigers receivers coach during Adams' career.
"He was a great example of how you could progress through hard work," Swinney said. "He played eight-man football in high school, then became a top-five pick. How many people have done that? I was an offensive assistant coach during his career, and we all took notice of his considerable skills."
Prior to college, Adams played eight-man football at Cambridge Academy, and then played a year at Fork Union Military Academy.
Adams earned All-American honors as a senior at Clemson in 2006, recording 12 1/2 sacks. He finished with 28 career sacks, tying the Clemson record held by Michael Dean Perry.
He was named was named the 2006 ACC Defensive Player of the Year, as was second in the ACC Player of the Year voting behind Georgia Tech's Calvin Johnson.
Adams' signature play as a Tiger came against Wake Forest in 2006, when he returned a fumble 66 yards for a touchdown.
No funeral arrangements have been announced.