Zsa Zsa Gabor Cause of Death ... Heart Attack

12/27/2016 8:56 AM PST

Zsa Zsa Gabor fell into a coma and died from a heart attack ... this according to the death certificate.

The death certificate -- obtained by TMZ -- says Zsa Zsa succumbed to cardiopulmonary arrest.  There were 2 other contributing factors ... coronary artery disease and cerebral vascular disease.

The document lists them as a "significant condition" contributing to her death as cerebrovascular accident coma.

TMZ broke the story ... Zsa Zsa died December 18th