Andy Griffith Cause of Death -- Actor Suffered Heart Attack

Andy Griffith passed away from a heart attack he suffered roughly 24 hours before his death ... so says the actor's death certificate.

According to the document, filed in Dare County, North Carolina and obtained by the AP, the 86-year-old Hollywood legend died Tuesday at 7:00 AM.

The document shows Griffith suffered a variety of illnesses for years ... including coronary artery disease, hypertension and hyperlipidemia.

As we previously reported, Griffith was buried in his family cemetery in N.C. just hours after he passed away.