Indian American cardiologist KP Shah said on Thursday that it was difficult to know the precise cause of pop star Michael Jackson's death, but it appeared to be a heart attack - the most common cause of sudden death in a 50-year-old individual.
Jackson, whose life of stardom and scandal kept him permanently in the headlines, was found unconscious at his rented Bel Air mansion in Los Angeles and was rushed to the UCLA Medical Centre, where his death was announced on Thursday.
Appearing on CNN Larry King Live, Shah, the director of cardiology at the Cedar Sinai Heart Institute, said: "My understanding, at least watching from the news reports, is that a physician had come to see him the night before, presumably for some symptoms. It's difficult to guess what they might have been. Sometimes before a heart attack, you may have some warning symptoms of either chest pain or shortness of breath or things of that nature."
"But I don't really know what exactly was the reason," he added.
Shah said sudden cardiac arrest is usually triggered by a blockage in an artery of the heart, but can also occur from a rupture of an aneurysm, a massive stroke, a massive blood clot in the lung and/or a massive blood loss. He also said use of recreational, sedative drugs or narcotics, such as amphetamine or cocaine, could also be a cause of sudden death.
The precise cause of death was unlikely to be detected even by an autopsy, the cardiologist said.
"If there is a structural abnormality of the heart muscle or the arteries of the heart that one would find in a traditional case of a heart attack, then we will have some clues from the autopsy. But sometimes, even with an autopsy, you cannot completely figure out the mechanism for sudden death," he said.
According to the doctor, prompt resuscitation would offer the only chance for survival.
"If somebody is standing by and starts CPR and summons the paramedics and if they can arrive and defibrillate, using a defibrillator within the first couple minutes of collapse, they have a reasonable chance to survive," he said, stressing it has to be immediate.
Shah said it appeared the paramedics arrived fairly promptly, but it was not clear how long it had been since Jackson collapsed.