Tony Coton is recovering at home after undergoing a quintuple heart bypass last month.
Sunderland's Head of Recruitment thanked staff at BMI the Alexandra Hospital for their care.
Coton joined the club, where he played as a goalkeeper in the 1996-97 season, in the summer and has been a vital part of the club's overhaul under Jack Ross.
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The Black Cats brought in 12 senior players for the League One campaign and saw 15 depart.
Coton previously worked as Steve Bruce's Chief Scout at Aston Villa.