'Whitney Houston's died of heart attack', says source

The LA County Coroner has released Whitney Houston's autopsy report and official cause of death is - accidental drowning.

From TMZ

The L.A. County Coroner has just released the singer's official cause of death -- accidental drowning ... but the report also notes heart disease and cocaine use were contributing factors to Whitney's demise.

A source connected to the investigation tells us it is "very possible" Whitney had a heart attack that caused her to lose consciousness and drown. The heart attack may have been triggered by hardening of the arteries as a result of cocaine use.

Investigators found no evidence of cocaine in the hotel room.