Mr Talabani's operation was announced more than a week after the event
Iraqi President Jalal Talabani is recovering from heart surgery in the US, Iraqi politicians say.
The operation took place at the Mayo Clinic on 6 August, an official from his party said. News of the procedure was only released eight days later.
The 74-year-old Mr Talabani left Iraq on 2 August to undergo unspecified medical tests and for treatment on his knee, his website said.
Mr Talabani was treated in Jordan for dehydration and exhaustion in 2007.
At the time newspapers speculated Mr Talabani was being tested for a heart condition, but his aides denied it.
An official from Mr Talabani's Patriotic Union of Kurdistan party said the president would leave hospital on Saturday and would go to Washington to rest.
"He still needs to undergo knee surgery," the official added.
Correspondents say there is a growing list of senior Iraqi politicians with health problems.
Speaker Mahmoud Mashhadani was flown to Jordan on Tuesday for treatment for his "deteriorating health", an aide said.
Meanshile, Vice President Tariq al-Hashemi was in Turkey this week undergoing medical tests.
Prime Minister Nouri Maliki had medical tests in London for heart problems earlier in the year.