Sage Stallone Died of Heart Disease, Not Drug OD Small amount of Hydrocodone did not contribute to death By Mary Papenfuss, Newser User Posted Aug 31, 2012 12:04 AM CDT Updated Aug 31, 2012 1:00 AM CDT 16 comments Comments Sage Stallone was found dead in his California home last month. (seleena581) (Newser) – Sylvester Stallone's son Sage died of heart disease, not a drug overdose, an autopsy has determined. There were no significant amounts of drugs found in the 36-year-old actor's system, reports the Los Angeles Times. The official cause of death was atherosclerotic coronary artery disease—hardening of the arteries—that caused a heart attack, chief coroner investigator Craig Harvey told the New York Daily News. Stallone had a small amount of the pain killer Hydrocodone in his system, but it did not contribute to his death, officials said. Sage's grandmother remained skeptical, saying that her grandson told her he was depressed and intended to overdose on drugs shortly before he was found dead last month in his California home. "How do you suddenly have a heart attack at 36? I don't believe it," Jackie Stallone told the News. "He was very depressed." Jackie's daughter Toni Ann Filiti, 48—Sylvester Stallone's half sister—died over the weekend from lung cancer.