Silvio Berlusconi has been placed in intensive care to recover after four-hour heart surgery to replace a defective heart valve, Milan’s San Raffaele hospital said giving no further details.
Sources told Ansa news agency the operation had been a success.
The 79-year-old former Italian prime minister is likely to take a month to recover.
Silvio Berlusconi served as prime minister four times but has since been convicted of tax fraud and bribery.
He was admitted to hospital last week after suffering a heart attack his doctor said could have killed him.
Silvio Berlusconi is expected to remain in intensive care for another 48 hours.
“Everything is okay guys, now I can speak more calmly,” Gianni Letta, an ally of Silvio Berlusconi, told AGI news agency.
On June 13, Silvio Berlusconi wrote on his Facebook page he was “concerned” by the looming operation.
“But I am also very moved by the very many demonstrations of appreciation, support and affection which I have received from everywhere, even from political rivals,” Silvio Berlusconi added.