Doctors inserted a balloon to help open his narrowed arteries to allow them to implant stents more easily. Altogether, the 84-year-old former president has had 11 stents implanted.

The surgery was a success, with Lee recovering well, but he will stay in the hospital for two or three days for observation, doctors said.

Doctors diagnosed Lee -- who has had heart surgery three times before -- with a narrowed coronary artery last month during the former president's routine checkup at the hospital.

Doctors ruled out a coronary bypass surgery considering his age, and instead conducted less invasive cauterization surgery.