Talabani, 79, was taken to a Baghdad hospital late Monday night and was treated for blocked arteries, the Voice of America reported Wednesday.
By Tuesday, officials said he was in stable condition.
A statement issued by his office Tuesday night said tests "have shown that the health status of his excellency was caused by hardening of the arteries."
Initial reports said Talabani has suffered a stroke, but his office downplayed the term, calling his hospitalization the result of "fatigue and exhaustion," CNN said.
Deputy Health Minister Issam Namiq said Wednesday medical specialists from Germany and Iran had arrived to help with Talabani's care, and that a British team was expected.