Sage Stallone's cause of death has been attributed to a heart attack possibly brought on by the 36-year-old's smoking. The son of Sylvester Stallone was suffering from coronary artery disease, and Sage had a history of heavy smoking, reports the Los Angeles Times.

The L.A. County coroner's office released details of the autopsy this week, though a coroner adding that toxicology tests came back "negative except for a sub-therapeutic level of hydrocodone", ruling out the possibility of a drug overdose. Smoking is among the chief causes of coronary artery disease because it can cause elevated blood pressure, raising the risk of clots. Sage's family said he had been cutting back on smoking lately, and had begun using an electric cigarette. The Los Angeles Police Department's North Hollywood Division arrived at Sage Stallone's home when he was found dead in July, though the case was quickly reassigned to the elite Robbery-Homicide Division. According to several sources, numerous pills will found at the scene, though the toxicology results confirm that they played no part in Sage's death.

Sage - who appeared in numerous movies with his father - was involved in a 2011 television documentary about the Rocky movies. He was also the co-founder of Grindhouse Releasing, specializing in video releases of restored B movies from the 1970s and 80s.