NBA's Sean Rooks: 'Died of Heart Disease' ... Coroner Says

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.