Actor Sylvester Stallone's son Sage Stallone's cause of death has been ruled a heart attack.  The Los Angeles County Coroner, who had delayed the release of the toxicology reports prior, said on Thursday that the 36-year-old had been suffering from heart disease, as he been diagnosed with a blockage of the arteries.

However, the late Stallone was also found to have "sub-therapeutic" levels of Vicodin in his body, according to TMZ.

A source closely connected with the Coroner stated that although it was "unusual" for someone of Sage's age to have such bad coronary issues, the problem was what ultimately led to his unexpected death, according to the gossip site.

Sage's body had been discovered at his residence in Los Angeles on July 13th, but many believe he may have been dead a lot longer. There had been previous speculation that he may have passed away from a drug overdose.  

The abrupt passing of Sage caught both his friends and family off guard. Due to his son's passing, Stallone had voluntarily skipped many of the promo events for his upcoming film "Expendables 2."  

The 66-year-old's publicist had described the star as "devastated and grief-stricken."  

While appearing on "The Tonight Show with Jay Leno" on Aug. 15th, Sly had been queried by the host on if doing the promotion for the movie aided in keeping his mind off of the horrific event.

"When life hits you pretty hard you can either go into a dark corner or you can say, 'Okay, fine, I'm going to find something to focus on,'" he responded.

Sage Moonblood Stallone had co-starred with his dad in two flicks; "Rocky V" and "Daylight."  He also had directing ambitions as he shot the film "Vic," which was showcased at the Palm Springs Film Festival.  

Sage was the oldest son of Stallone's first wife Sasha Czack.