NEW YORK - Former President Bill Clinton is in good spirits and his prognosis is excellent after undergoing a procedure Thursday to restore blood flow in one of his coronary arteries, his doctor said. Clinton, 63, was hospitalised at New York-Presbyterian Hospitals Columbia campus after experiencing chest pains over several days, according to Dr Allan Schwartz, the hospitals chief of cardiology. Clinton has been discharged from the hospital on Friday. Two stents were used to restore blood flow to a coronary artery Thursday after images revealed that a bypass graft part of a quadruple bypass surgery that Clinton underwent in 2004 was blocked, Schwartz said. An electrocardiogram and a blood test showed no evidence of a heart attack, Schwartz said. Hes in good spirits, and we hope to have him go home tomorrow, Schwartz told reporters Thursday night. Schwartz said the need for the procedure had nothing to do with Clintons post-bypass diet or exercise, which Schwartz called excellent. Rather, Schwartz said, this is part of the natural history of the bypass treatment. He really toed the line in terms of diet and exercise. He really followed the programme, Schwartz said, adding he told Clinton that hed be allowed to return to work Monday. The stents have opened the artery that the blocked bypass graft was supposed to service, Schwartz said. Stents are tiny balloons that are threaded into a patients heart vessels where they are inflated, pushing plaque against the vessel wall and increasing blood flow. The grafts blockage isnt unheard of, because that particular type of graft has a 10 percent to 20 percent failure rate after six years, Schwartz said. However, a bypass graft at a different artery the main artery in the front of Clintons heart still looks pristine, Schwartz said. We know from multiple studies that if that bypass is open at this point ... it will remain open, he said. Schwartz said Clinton was up and walking about two hours after Thursdays procedure. In a written statement, Douglas Band, counsellor to the former president, said: President Clinton is in good spirits and will continue to focus on the work of his foundation and Haitis relief and long-term recovery efforts. Clintons daughter, Chelsea Clinton, and wife, Secretary of State Hillary Clinton, were with him at the hospital Thursday night, Schwartz said. Hillary Clinton was scheduled to leave Friday on a planned trip to the Middle East, but her departure has been delayed until Saturday, a senior US official said.