Three-time world surfing champion Andy Irons died at age 32 from a heart attack he suffered 30 hours after apparently taking cocaine, his family members said in releasing results of an autopsy and toxicology report.

Irons, regarded as one of the world's greatest competitive surfers and big-wave riders, was found dead in November in a hotel home in Dallas, Texas.

It was reported then that he was suffering from the severe tropical disease dengue fever.

An autopsy conducted by a medical examiner in Texas ruled out dengue fever and found Irons died from cardiac arrest due to a severe blockage of a main artery of the heart, his family said in a statement.

The family asked independent forensic pathologist Dr Vincent Di Maio to review the autopsy report, and he concluded Irons suffered from hardening of the arteries.

"A plaque of this severity, located in the anterior descending coronary artery, is commonly associated with sudden death," Di Maio said in a statement.

The doctor also said that while hardening of the arteries usually begins to appear in people nearing the age of 50, Irons had a "genetic predisposition" to early development of the disease.

The family said Irons caught typhoid fever five years ago, which could have resulted in damage to his heart muscle.

The autopsy report lists a secondary cause of death as "acute mixed drug ingestion," and cited the presence of Xanax, which Irons used to treat anxiety and insomnia, in his system, according to the family.

Also found in Irons' body was the substance benzoylecgonine, which a second independent expert, forensic toxicologist Gary H7. Wimbish, described as a byproduct from the metabolism of cocaine, according to the statement.

Wimbish said it appears Irons used cocaine about 30 hours before he died, his family said.

"The family believes Andy was in some denial about the severity of his chemical imbalance and tended to blame his mood swings on himself and his own weaknesses, choosing to self-medicate with recreational drugs," the Irons family said in the statement.

A spokesman for the medical examiner said the official autopsy and toxicology report will be released once an injunction sealing those records expires on June 20.

The Irons family said in December they sought a court order to delay the report's release because Irons' widow, Lyndie, was about to give birth to the couple's son and they wanted to avoid unnecessary stress on her.

Before his death, Irons pulled out of the Rip Curl Search surf contest in Puerto Rico with flu-like symptoms, and he was put on an intravenous drip for hydration, his family said.

He then boarded a plane from Miami to try to reach his home in Hawaii and rejoin his wife, but missed a connecting flight and ended up checking into the Dallas hotel where he died.

He won three consecutive world titles from 2002 to 2004.

- Reuters