Marcello Giordani, a heartfelt, stalwart and, at his best, inspired tenor who was a fixture at the Metropolitan Opera and other major houses around the world, died on Saturday at his home in Augusta, Sicily. He was 56.

The cause was a heart attack, his manager, Katherine Olsen, said.

Mr. Giordani appeared more than 240 times with the Met in 27 roles, including in two company premieres, five new productions and the opening nights of two seasons.

When he opened the 2006-7 season, the first of Peter Gelb’s tenure as general manager, in Puccini’s “Madama Butterfly,” Anthony Tommasini wrote in The New York Times that Mr. Giordani sang “with full-bodied Italianate passion; warm, rich tone; and clarion top notes.”