During a 1985 appearance on Good Morning America, Rivers, then 52, confessed to host Joan Lunden that she had heart arrhythmia.
“Every once in a while on stage, you’ll hear va-voom!” she says in the video. “I go, ‘Uh oh’…It scares the hell out of me.”
She then admits that due to her condition, she gets nervous about going under anesthesia.
"When you go under, say for plastic surgery or something like that, that's when your heart can go out of kilter,“ she explains. “So I'm always very careful."
“Certainly, they suspect the anesthesia was the issue, based on conversations between the staff and city medics,” an insider close to the investigation told Radar.
Rivers will be remembered with a red carpet-lined star-studded funeral in New York on Sunday.
Watch the comedienne’s health confession in the clip below.