The surgery was successful and Gentiloni, 62, was likely to remain in hospital for a few days, aides said when announcing the news earlier in the day.
“Thanks for the affection and well-wishes. Doctors and medical staff were excellent. I'm well. Soon I'll go back to work,” Gentiloni said on Twitter on Wednesday evening.
The premier was taken to hospital after complaining of discomfort on his return to Rome on Tuesday from an official visit to Paris, with doctors deciding he should undergo an angioplasty.
This is a procedure to widen a blocked or narrowed blood vessel, usually an artery.
“We exchanged messages this morning and I am sure that he will be back at work very soon,” junior minister Benedetto Della Vedova had told reporters before the premier's tweet.
Gentiloni has been conducting a tour of European capitals following his appointment last month to replace Matteo Renzi, who resigned following a crushing referendum defeat.
He was in Paris on Tuesday to meet French President Francois Hollande and had been due to fly to London on Thursday to meet his counterpart Theresa May, a trip that has now been postponed.
However, Gentiloni is still due to meet Palestinian President Mahmoud Abbas in Rome on Friday.
With Hollande, the Italian premier discussed celebrations to mark the 60th anniversary in March of the Treaty of Rome, the accord that established what would eventually become the European Union.