German playwright Bertolt Brecht may have died due to an undiagnosed childhood illness, new research claims.
After looking through medical records, University of Manchester professor Stephen Parker found Brecht suffered from rheumatic fever as a child.
Documents showed the illness attacked his heart and motorneural system, triggering chronic heart failure.
There has long been speculation about Brecht's sudden 1956 death, officially attributed to a heart attack.
Rheumatic fever was a little understood condition in the early 1900s.
As a result, the future poet and theatre director was simply labelled a nervous child with an enlarged heart.
But records show Brecht, born in Bavaria in 1898, also suffered from Sydenham's chorea, a disease linked to rheumatic fever.
Further research showed his condition was compounded by urological complaints.
"Brecht was a physical mess, whose chronic conditions would eventually kill him," claims Professor Parker.
"Yet he had an extraordinary poetic and theatrical talent, which enabled him to transform his wretched physical weakness into a peerless strength.
"We can now be sure that virtually all his life he suffered from an organic condition, which proved fatal as heart failure.
"I never believed his problems were merely the result of neurosis - as some have argued," he continued.
"It's just that no one had ever taken the trouble to investigate his medical history."
Brecht is best known for such plays as Mother Courage, The Threepenny Opera and The Caucasian Chalk Circle.
The 1983 death of rock star Billy Fury was also attributed to rheumatic fever he contracted as a child.