Just over one month after R&B supernova Whitney Houston was found dead in the bathtub of a Beverly Hilton hotel room, the Los Angeles County Coroner's Office is offering an official cause of death: Drowning due to heart disease and cocaine use. The singer's history of drug abuse is well-known, but how big of a role did drugs play in her death? Here, a brief guide:

What did we already know about Houston's death?
The "I Will Always Love You" singer was discovered in the bathtub, "underwater and apparently unconscious." Paramedics rushed to the scene and performed CPR for 20 minutes, but were unable to revive her. Small quantities of prescription drugs were found in Houston's suite, and the singer's most recent room service order included a Heineken and a glass of champagne. In the days before her death, Houston was spotted at the hotel "acting strangely, skipping around a ballroom, and doing handstands near the hotel pool," leading to speculation that she had been using drugs.

And now the coroner has an official cause?
Yes. L.A. County Coroner's chief Craig Harvey revealed that Houston suffered from atherosclerotic heart disease, which left her with a 60 percent occlusion in the arteries. The heart condition combined with chronic cocaine use resulted in a "cardiac event," which ultimately led to her drowning. Harvey confirms that Houston used cocaine immediately before her death.

How does cocaine use lead to heart disease?
The chronic use of cocaine accelerates the formation of plaques inside blood vessels, which over time can lead to the "severe narrowing of the vessels," says Brian Alexander at MSNBC. Eventually, as the condition develops, it can cause a heart attack, stroke, or a transient ischemic attack, better known as a "ministroke." Such a ministroke can leave victims disoriented, causing them to faint — a deadly event if the person happens to be in the bathtub. These ministrokes occur when bits of the built-up plaque break off and block a vital vessel, the result of "something stimulating, like exercise" — or, in Houston's case, taking a hit of a stimulating narcotic like cocaine.

Were their other drugs at play?
In addition to the cocaine, toxicology reports also showed that Houston had marijuana, Xanax, the muscle relaxant Flexeril, and the allergy medication Benadryl in her system at the time of her death. The drug cocktail is "not believed to have contributed to her death," but Today show chief medical editor Dr. Nancy Snyderman cautions that the drug interactions shouldn't be ignored. "It doesn't have to be one drug in a whopping amount; it can be a lot of little things, and when you compound it, it can be enough to cause death."

Are there other unanswered questions?
For one, it's not known how long Houston suffered from her heart condition. Also unclear: The exact amount of cocaine found in her system, but the full coroner's report, to be released in two weeks, should clarify that. But "perhaps the biggest mystery still surrounding Houston's death," says Kevin Dolak and Eileen Murphy at ABC News, is whether she died before or after she became submerged in the bathtub. "Was she incapacitated and alive when she went under water, or was she already dead?"

Sources: ABC News, Huff. Post, LA Times, MSNBC, Wash. Post, TMZ