Antonio Cassano underwent heart surgery this morning to correct a congenital defect which was uncovered this week.
The procedure, which took around 30 minutes to complete, is understood to have gone according to plan.
The Italian international has been in hospital since Saturday night after suffering an ischemic attack on the flight home from Milan's 3-2 win at Roma.
The 29-year-old subsequently underwent a series of tests after being admitted to the neurology wing of a Milan clinic.
During those investigations, it was discovered that the former Bari attacker would require surgery to fill a small hole between the atriums.
The operation was carried out by professor Mario Carminati.
It's expected that Cassano will be able to return to action, but that may not be for at least another six months.