Ex-NBA player and 76ers assistant coach Sean Rooks died of heart disease... this according to the Philadelphia Medical Examiner's Office.
Sources told TMZ Sports ... the 46-year-old suffered a heart attack during dinner on Tuesday night.
Now, a rep for the M.E.'s office says the coroner has examined Rooks' body and "believes Rooks died of heart disease."
We're told additional testing will take place to confirm that finding.
Heart disease makes it difficult for blood to flow through the heart -- and can often lead to a heart attack.