Repeated cocaine use has been proven to raise the risk of heart attack risk, according to a 2008 report from the Beth Israel Deaconess Medical Center in Boston. Ten percent of heart attacks in people 18 to 45 years old were associated with more than 10 uses of cocaine over their lifetime.
The study led the American Heart Association to issue a statement urging doctors to consider the use of cocaine in young people with unusual cardiovascular or lung complaints.
Although Houston had been a chronic cocaine user throughout her life, as noted Thursday by the chief coroner, Fishbein said even a person with a normal heart can die of cocaine use and that if someone takes too much cocaine, he or she can die from even one exposure.
Perhaps the biggest mystery still surrounding Houston's death is whether the singer died before or after she was submerged underwater in her hotel bathtub: was she incapacitated and alive when she went under water, or was she already dead?
Medical examiners tend to say that someone has died of drowning if they are found in the water, and it is likely that water was found in Houston's lungs. In the report released Thursday, the coroner lists drowning first.
Fishbein says there are two possibilities in Houston's case.
"People can have what is called agonal respirations. That is, you can have a gasping breath, even after the heart is stopped. There are two possibilities: that she was incapacitated and alive when she went under the water, or she was basically dead, and the water got in with these respirations."
"How does someone die in a bathtub?" he asked. "It's not like they're swimming the English Channel. So she had to have been incapacitated. And I think that was due to the cocaine causing an abnormal cardiac rhythm."
Dr. Drew Pinsky, an addiction specialist and host of "Dr. Drew" on HLN, says that while the official cause of death was drowning, he believes Houston died from addiction.
"The cocaine probably caused some sort of cardiac arrhythmia or damage to the heart muscle, which resulted in her losing blood pressure and consciousness, and slipping into the water and drowning," Pinsky said.
It is still possible that these questions will be answered, and much of the mystery surrounding the star's death might still become clear, when the final coroner's report is released. It is expected within the next two weeks.