Raquel Welch suffered a cardiac arrest ... according to her death certificate.
The document, obtained by TMZ, also says one of the underlying causes of her death was Alzheimer's disease. The actress had not publicly revealed she was battling Alzheimer's.
We broke the story ... Raquel died Feb. 15 at her home in Los Angeles after what her family described as a "brief illness." The death certificate says she passed away at 2:25 AM, and she's since been cremated.
According to the National Institutes of Health, 90% of people who suffer cardiac arrest outside of a hospital die, typically within minutes.
82-year-old Raquel's long and successful Hollywood career is noted on the certificate ... the doc says she spent 60 years as an actress in the entertainment industry.
Remember ... Raquel became an international sex symbol way back in 1966 after back-to-back starring roles in "One Million Years B.C." and "Fantastic Voyage."