Patrick Muldoon’s sister has described his death as a “nightmare” she can’t wake up from.

Muldoon, who rose to fame via his roles on TV shows including Saved by the Bell and Days of Our Lives, as well as films such as Starship Troopers, passed away suddenly on Sunday, April 19.

Aged just 57 at the time of his death, reports have speculated that Muldoon succumbed to a heart attack. His sister, Shana Muldoon Zappa, has now offered further details as to the moments that immediately preceded the end of his life.

Shana described her brother as the ‘sunshine in every room’ and the ‘life of the party’, explaining that he had been having a “normal morning coffee” with his partner of two years – ex-entertainment lawyer and film producer Miriam Rothbard – when the fatal medical incident unfolded.

“He went into the bathroom while she was on the phone,” Shana told the Daily Mail. “‘And she just thought it seemed [like he’d been in there] a little long…it was probably 10 minutes.”

Shana continued: “So she went in and he was on the floor, not breathing. She called 911 and she was trying to bring him back, then the paramedics got there.

“My parents were at our house because we’re all in LA and we all ran over there. But by the time we got there, he was gone.”

According to Shana, Patrick’s father, Patrick Muldoon Sr, “fell and fractured his shoulder” attempting to rush to Patrick’s home. He is currently in hospital receiving treatment.

Speaking to the sudden nature of his passing, Shana said that Patrick had appeared well the night before.

“We have videos the night before he was sending us and he was happy as can be,” the surviving subling said. “It’s just a shock.

“He’s so healthy. He’s an ex-athlete. He goes to jiu-jitsu. He’s a martial artist. He runs, he works out. It seems like he was in a highlight in his life. And then to just [die] suddenly, it’s just unbelievable.

“We just had this beautiful Easter together,” Shana continued. “I talked to him – he was supposed to have lunch with my husband yesterday. It’s just all good old high stress of Hollywood and always on the go, certainly.”

The 48-year-old also claimed that there had been no warning signs, stating: “There was no other signs of anything.

“So the good news is, it seems like it was sudden and there was no suffering. He didn’t hit his head or anything.”

According to the Centers for Disease Control and Prevention, one person gets a heart attack every 40th second in the US. More than 800,000 people suffer from a heart attack in the country each year.