After the 1968 Aldeburgh Festival, Britten came down with an infection, which was diagnosed as sub-acute bacterial endocarditis. This disease had killed Mahler, but Britten had the advantage of massive doses of antibiotics. The illness led to the discovery of a valvular heart-lesion, which was probably caused by rheumatic fever as a child. In 1971-72, symptoms of a heart disease recurred. For several years during the latter period of his life Britten had complained of a pain in his left arm when conducting.
During Britten's year off composing, Peter Pears wished that Britten should never lose faith in music, so he resumed composing after taking a year off. Britten desperately wanted to finish his last opera, Death in Venice. He did not want to have surgery until he had completed it. Eventually he gave in, though. In 1973, he had an operation to replace a heart valve. He had to be wheeled in on a cart to see its performance for the first time.
According to Pears, Britten had no fear of dying, and no convictions as to what followed death. He died 4 December 1976, in Aldeburgh.