Jackson's Death Puts Spotlight on Sudden Cardiac Arrest

June 29 -- FRIDAY, June 26 (HealthDay News) -- Pop star Michael Jackson probably did not die on Thursday of a heart attack but perhaps something even more deadly -- sudden cardiac arrest, experts say.

It's not yet clear whether Jackson went into sudden cardiac arrest in his Los Angeles home, but that assumption has been made by many experts "on the basis of the report that his heart stopped, and he received resuscitation attempts," said Dr. Stephen Nicholls, a cardiologist at the Cleveland Clinic.

"The ultimate question is whether death was due to a problem with the heart or another problem," Nicholls said. An autopsy was performed Friday, but additional tests are to be performed and the results aren't expected for six to eight weeks, the Los Angeles County coroner's office said.

A heart attack happens when a coronary artery is blocked and some heart muscle dies. In sudden cardiac arrest, the heart simply stops beating, and the ventricles, the two blood-pumping chambers at the bottom of the heart, go into fibrillation, a useless fluttering.

When that happens, survival time is measured in minutes. The usual estimate is that the chance of survival goes down 10 percent for every minute that the heart stops beating. That means that Jackson probably could not have been saved, even though he was staying in a home that is only a six-minute drive from the UCLA Medical Center, where paramedics brought him for treatment.

The underlying causes of heart attacks and sudden cardiac arrests are often the same, said Dr. Kirk Garratt, director of the Heart and Vascular Institute of Lenox Hill Hospital in New York City.

"Most cardiac arrest is related to ischemic heart disease," Garratt said. Ischemia is blockage of an artery. "Most of the time, ventricular fibrillation takes place when an artery is blocked off. When that happens, if you don't get the rhythm corrected right away, you lose cardiac function and everything stops quite quickly."