Clint Eastwood's longtime partner Christina Sandera died of a heart attack

A representative from the Monterey County Health Department confirmed the cause of death.

Atherosclerotic coronary artery disease was cited as an additional condition that led to Sandera's death.

It occurs when deposits of fat, cholesterol, calcium and other substances accumulate in artery walls, causing blood vessels to harden and narrow, which restricts blood flow around the body.

When they plaques rupture they form a blood clot that can block the flow of blood more dramatically, which can result in a heart attack or stroke.

A Warner Bros spokesperson told The Hollywood Reporter no further information would be given on Christina's death as Clint wants to privately grieve.

The Oscar-winner confirmed Christina had passed away in a statement issued on 18 July, in which he said: "Christina was a lovely, caring woman, and I will miss her very much."

He and Christina had been together since 2014 after meeting while she was working as a hostess at Clint's Mission Ranch Hotel and Restaurant in Carmel-by-the-Sea, California.

They made their red carpet debut at the 2015 Academy Awards and even though they lived a relatively private life, Christina was a regular plus-one with Clint to his red carpet events.

She was also very close to his large family and in 2018 joined three of his eight kids, as well as his granddaughter and first wife Margaret Johnson at the premiere of his film 'The Mule'.

Two years later, Clint's son Scott Eastwood, 38, said the whole clan planned to celebrate his dad's 90thbirthday.

He added: "We're going to do just a family thing. Very calm, very mellow.

"He doesn't like birthdays. He's just sort of like, 'I don't want to do birthdays ... we'll sneak a cake in there, definitely.

"He probably won't like it, but we'll put one in."