According to his autopsy report, Stallone died from atherosclerotic coronary artery disease—a form of heart disease, according to Craig R. Harvey, Chief Coroner Investigator and Chief of Operations for the Los Angeles coroner's office.
Contrary to previous speculation that the filmmaker passed away from a drug overdose, Stallone's toxicology report was negative except for a "sub-therapeutic" level of hydrocodone.
The full report is expected to be released next week.
It is unclear if Sage had been suffering from heart problems in the past, but this isn't the first time one of Sylvester Stallone's children has suffered from a heart condition. In 1996, one of Sylvester's daughter with wife Jennifer Flavin, Sophia, underwent successful surgery to repair a hole in her heart, just a few months after she was born.
Sage's private, family-only funeral was held July 21 at St. Martin of Tours Catholic Church in Los Angeles.