A man has been found guilty of manslaughter for killing a heart surgeon in a one-punch attack at Box Hill Hospital in Melbourne’s east last year.

Joseph Esmaili, 24, punched Dr Patrick Pritzwald-Stegmann in the head during an argument in the foyer of the hospital in May 2017.

The 41-year-old surgeon was knocked unconscious and fell backwards, hitting his head on the tiled floor.

He died in hospital a month later.

The pair began arguing after the surgeon asked Esmaili and his friends to stop smoking in a non-smoking area outside the hospital, the Victorian Supreme Court trial was told.

CCTV was played to the jury which showed the men arguing in the moments leading up to the punch.

Witnesses gave evidence Esmaili was asked to leave the hospital, but responded by telling Dr Pritzwald-Stegmann, “You need to suck my d––”.

Dr Pritzwald-Stegmann was then overheard angrily retorting: “You just spat in my face.”

The families of both Dr Pritzwald-Stegmann and Esmaili were in court to witness the verdict being handed down and did not react when it was read out.

Esmaili has been remanded in custody and will return to court in March for a plea hearing.

-ABC