Tyler Christopher, an actor best known for his long-running role on the TV soap opera “General Hospital,” has died. He was 50.

A former co-star, Maurice Benard, said on Instagram that Mr. Christopher had died Tuesday morning in his San Diego apartment because of a “cardiac event.” Mr. Christopher’s death was also confirmed by his manager, Chi Muoi Lo.

Mr. Christopher won a Daytime Emmy Award in 2016 for best lead actor as Stefan DiMera on “Days of Our Lives,” another soap opera. He is best known for playing Nikolas Cassadine on “General Hospital” from 1996 to 2016, while also appearing in several other TV shows and movies.

“Tyler was a truly talented individual that lit up the screen in every scene he performed and relished bringing joy to his loyal fans through his acting,” Mr. Benard said. “Tyler was a sweet soul and wonderful friend to all of those who knew him.”

He described Mr. Christopher as a mental health advocate, adding that he spoke openly about his struggles with bipolar disorder, depression and alcohol.

Mr. Christopher wrote about his struggles with bipolar disorder and alcohol abuse in Reader’s Digest. He said he regularly saw a psychiatrist and a therapist and took medications to treat his mental health conditions.

In a social media post from last year, he reflected on how far he had come since turning 40.

“In the decade since then my daughter was born, I won an Emmy, was the lead actor in 4 television shows, completed a dozen movies, lived in a half dozen states, relapsed and recovered, survived a traumatic brain injury,” he wrote.

But he said he was looking forward to a “quieter life” with his two children.

He is survived by his children and his father, Mr. Benard wrote.

Mr. Lo said the news of his death “was incredibly shocking”

“He was a very gifted actor, and more importantly, an amazing friend,” Mr. Lo said. “My heart goes out to his friends and family who loved him so much.”