Albert L. Ortega/WireImage
08/30/2012 at 07:00 PM EDT
Heart disease, not drugs, was the major cause of Sage Stallone's untimely death
earlier this summer at age 36, the Los Angeles County coroner announced Thursday.
After conducting an autopsy as well as a full toxicology screen, the coroner cited atherosclerotic coronary artery disease as the cause of death, and said that the drug test was negative except for a small, "sub-therapeutic" level of hydrocodone, more commonly known as Vicodin.
The department's full report is expected next week.
Friends of the horror movie distributor and actor told PEOPLE
that Sage lived a very different life from his famous father, avoiding the gym and consuming little more than junk food, soda and cigarettes. They also said he routinely took various prescription medications.
Los Angeles police said they found large empty prescription bottles at Sage's home on July 13 while investigating his death
Sage was laid to rest
on July 21 in Los Angeles.
Sylvester Stallone said after his son's death, "It's very, very tough. It's a horrible situation, but time hopefully will heal, and you try to get through it."