Koch spokesman George Arzt said the former mayor, 84, underwent the surgery at New York-Presbyterian/Columbia hospital, where he was already recovering from a heart valve replacement and quadruple bypass surgery, The New York Times reported.
The bypass procedure was performed June 19 to repair damage Koch had sustained from a heart attack suffered 10 years ago, the newspaper said. Koch had been active while recuperating from that surgery, reportedly taking a call from President Barack Obama and issuing political endorsements.
Koch represented New York in Congress from 1969 until 1977, when he resigned following his election as New York mayor. He was re-elected mayor twice but lost his bid for a fourth term in 1989.