It has emerged that Sylvester Stallone's son Sage died of a heart disease and not a drug overdose as originally suspected. His official cause of death was released by the Los Angeles County Coroner today after an autopsy and toxicology tests were performed following his untimely death last month at the age of 36.No drugs were found in Sage's system aside from a sub-therapeutic level of Hydrocodone, more commonly known as Vicodin.Atherosclerotic coronary artery disease was cited as the official cause of death and the coroner's full report is expected next week. Friends told People magazine that Sage often indulged in junk food, soda and cigarettes, as well as prescription drugs. He was also diagnosed with a heart murmur at the age of 10.Following his death on July 13, there was much speculation that drugs were the cause. Sylvester's son was found dead in his home with bottles of pills scattered all over his room, the L.A. County Coroner reported at the time. There were also claims that law enforcement sources revealed that authorities investigating the death of Sage believed he was a drug dealer.Insiders apparently told TMZ that a 'likely scenario' was Sage was dealing Hydrocodone but not an addict himself.A key factor in the theory was said to be the late actor's weight.At 188lbs and 5'7", Sage didn't have the thin frame usually associated with addicts.TMZ was reportedly told, 'He was pudgy, and drug addicts are almost always rail thin.'The website's source claimed that no Hydrocodone tablets were found in Sage's house, but that there were over 60 gigantic empty prescription bottles.Scott Ross, a Stallone family friend, who was also assisting with the investigation, spoke out about his official cause of death.'Here are the facts: Sage was diagnosed at age 10 with a heart murmur, he led a very sedentary lifestyle and also had an addiction to cigarettes  - he smoked up to two packs a day - and drank a LOT of sugary soda,' Ross told Radaronline.com.'There was never any evidence that Sage was a drug dealer, a drug addict or suicidal. 'The empty prescription pill bottles recovered from Sage's house were going to be used as props in an upcoming movie he was going to work on.'The result may come as closure for Sage's famous father and the rest of his family. Since his son's death, the actor has been keeping busy by taking a holiday abroad with wife Jennifer Flavin and their three daughters, as well as promoting his movie The Expendables 2. Following his son's death, the Hollywood actor released an emotional statement, talking about his 'agonizing' loss.He said, 'When a parent loses a child there is no greater pain... This agonizing loss will be felt for the rest of our lives.’'Sage was our first child and the centre of our universe and I am humbly begging everyone to have my son's memory in full left in peace.'During a recent appearance on Good Morning America to promote Expendables 2, in reference to his son’s death, Stallone said, 'It's tough. It's very, very, tough.'The actor also admitted that family and friends helped him with his grief. He also added that being involved with promoting his latest movie helped keep him busy.Daily Mail