According to 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.
