On July 13, "Rocky" star Sylvester Stallone lost his 36-year-old son, Sage Stallone. Los Angeles coroner's office announced that the actors son did not suffer from the speculated drug overdose, but rather a heart attack. 

Reuters reports that Sage Stallone suffered from atherosclerosis, a coronary heart disease that had caused his heart attack. According to the American Heart Association, atherosclerosis is the term for a "buildup of fatty substances, cholesterol, cellular waste products, calcium and fibrin " in the inner lining of an artery. The buildup in that artery is called plaque, and can block the blood flow.

Sage was found dead in his Los Angeles apartment on July 13. The filmmaker and actor  was found with prescription bottles, causing many to speculate that Sylvester Stallone's son died of a drug overdose. However, Lt. Fred Corral revealed that a small and "acceptable level" of hydrocodone, a sedative, showed up in Sage's toxicology report.

"There was no signs of an overdose," Lt. Corral explained. "It was just a natural death."

Sage Stallone was the youngest of Sylvester's two sons with Sasha Czack. The pair had been married for 10 years, divorcing in 1985. 

The "Expendables 2" actor recently lost his half-sister as well, Toni-Ann Filiti. Filiti died of lung cancer this past sunday at the age of 48, reported the Huffington Post

Sylvester Stallone, 66, has kept a low profile since the death of his son. According to Reuters, the actor had no comment on Thursday after the coroner's office revealed the results of Sage's death.