The leader of the world's Orthodox Christians underwent stent surgery in New York on Wednesday after feeling unwell during a US visit, the church said.
Ecumenical Patriarch Bartholomew I, 81, "successfully underwent stent placement at Mount Sinai Hospital," the Greek Orthodox Archdiocese said in a statement.
The patriarch will be discharged Thursday after spending the night at the Manhattan hospital, it said.
A stent placement is a common procedure in clogged arteries to increase blood flow to the heart.
Bartholomew has maintained his schedule and before his hospital visit Wednesday met Eric Adams, who was elected mayor of New York the evening before.
The patriarch on October 25 met at the White House with President Joe Biden hours after being discharged from a Washington hospital.
The archdiocese said at the time that the Istanbul-based religious leader was feeling unwell after his long flight and was put under observation "out of an abundance of precaution."
The patriarch has sought US support amid a renewal of tensions in Turkey, where President Recep Tayyip Erdogan last year controversially reconverted Hagia Sophia -- originally the Byzantine Empire's main cathedral -- into a mosque from a museum.
Elected in 1991, Bartholomew has been outspoken on the environment and has cultivated closer relations both with Islam and Roman Catholicism.
In 2013, he attended the investiture of Pope Francis, the first patriarch to do so since the 1054 schism between Byzantium and Rome.