At Michael's time of death, "In fact, the Los Angeles County coroner's report shows Jackson was a fairly healthy 50-year-old before he died of an overdose. His 136 pounds were in the acceptable range for a 5-foot-9 man. His heart was strong with no sign of plaque buildup. And his kidneys and most other major organs were normal.
Still, Jackson had health issues: arthritis in the lower spine and some fingers, and mild plaque buildup in his leg arteries. Most serious was his lungs, which the autopsy report said were chronically inflamed and had reduced capacity that might have left him short of breath.
However, according to the document, the lung condition was not serious enough to be a direct or contributing cause of death.
"His overall health was fine," said Dr. Zeev Kain, chairman of the anesthesiology department at the University of California, Irvine, who reviewed a copy of the autopsy report for the AP. "The results are within normal limits."
Jackson died at his rented Los Angeles mansion June 25 after his personal physician, Dr. Conrad Murray, administered the anesthetic propofol and two other sedatives and requires constant monitoring.
Aside from propofol and the sedatives, the only substances found in his system were the local anesthetic, Lidocaine, sometimes used to numb injection sites and ephedrine, a commonly used resuscitation stimulant.
No other drugs — legal or otherwise — were detected, nor was any alcohol.
Kain said he was surprised that three other sedatives, known as benzodiazepines, were present with propofol. Anesthesiologists sometimes mix one "benzo" with propofol to help put a patient under, but using three increases the danger for the patient.
"People don't mix the benzodiazepines together because they interact with each other and increase the risk of respiratory arrest," Kain said, adding it was likely Jackson first stopped breathing and then suffered cardiac arrest."
http://www.cbsnews.com/news/autopsy-michael-jackson-was-healthy/
As this article brings out, the three sedatives found in Michael's system increased the risk of respiratory arrest. Conrad Murray failed to monitor Michael constantly. Thus Michael died.