Sage Stallone Cause of Death — Heart Attack … Not Drugs

exclusive 0830_sage_stallone_gettySylvester Stallone“s son, Sage Stallone, died from a heart attack … and no drugs were found in his system … our sources has learned.

The L.A. County Coroner has determined Sage died from natural causes.  As for why he had a heart attack, we”re told there was evidence of heart disease. 

A source connected with the Coroner tells our sources … it was “unusual” for a person Sage”s age — 36 — to have such advanced coronary problems, but that”s what killed him.

Sage”s body was found July 13, but he may have been dead days earlier.