Harvey Weinstein Rushed to Hospital for Emergency Heart Surgery

1:31 PM PT -- Harvey Weinstein is "not doing great," his rep Juda Engelmayer tells TMZ.

We're told the fallen film legend is having "major heart surgery" today after he first began experiencing chest pains at Rikers Island prison.

However, Weinstein still plans to appear in court on Thursday ... but will only attend if he's well enough to do so.

Harvey Weinstein is undergoing emergency surgery mere days before he is due in court in NYC ... TMZ has learned.

The controversial film producer was rushed to Bellevue Hospital in New York from Rikers Island prison Monday for emergency heart surgery after experiencing pains in his chest, his lawyer confirmed to TMZ.

Weinstein was held at Rikers ahead of his court appearance, where prosecutors are hoping to secure a new indictment against Weinstein after his prior rape conviction in NYC was overturned in April.

Weinstein has been accused of sexual misconduct by more than 80 women ... though he maintains his innocence, claiming his past sexual encounters were consensual.

Ahead of this health crisis, Weinstein had appeared in court in a wheelchair ... and specifically asked to stay at Rikers, as he was receiving medical care there.

He was previously hospitalized this summer to deal with a variety of issues, including diabetes, high blood pressure, spinal stenosis, and fluid on his heart and lungs. While in the hospital, he contracted COVID-19 and double pneumonia ... which required further medical care.

In April, his attorney, Arthur Aidala, confirmed to TMZ his client's health issues were a "train wreck," and shared the Oscar winner had been hospitalized in Manhattan at the time.

We're sure more developments are likely ... so, stay tuned.