"He had a relatively routine quadruple bypass operation. We left the operating room around noon, and he is recovering normally at this point. So, I think now everything looks straightforward," said Dr. Craig R. Smith, chief of cardiothoracic surgery, who led the surgical team.
Sen. Hillary Rodham Clinton, who was at the hospital with daughter Chelsea before the surgery, released a press statement thanking the doctors.
"These past few days have been quite an emotional rollercoaster for us," Clinton said in a statement read by New York Presbyterian Hospital President and CEO Dr. Herbert Pardes. "We are so deeply thankful for the good news we have received today."
Clinton is awake, though sedated in the hospital's intensive care unit, and has a breathing tube in his chest so he is still unable to speak. Doctors said based on his progress, Clinton would probably be able to head home by the weekend, but recovery will take weeks. It takes two to three months for patients to be back at 100 percent, the doctors said.
Preparations for the surgery began at about 6:45 a.m. EDT and surgery began around 8:00 a.m. EDT. Prior to surgery, Clinton had seemed in a good mood and ready to proceed, and "approached the operation in a very positive way," Smith said.
Clinton, 58, was hospitalized Friday after suffering chest pains and shortness of breath. Dr. Allan Schwartz, chief of cardiology at New York Presbyterian, said that Clinton's arteries were 90 percent blocked and it is likely that had he not been treated, he would have had a "substantial" heart attack.
Doctors not involved in caring for the president said Clinton's age and general health raised the chances of a successful surgery, which has become a fairly routine procedure. Doctors say Clinton should recover within a month or two.
"This is an operation which is performed about 500,000 times a year and patients do very well, particularly in his age group," Dr. Tony Parente told FOX News, adding that the first 24 hours after surgery are the most precarious.
Schwartz said that Clinton, who is very physically active and "extremely healthy," first noticed a few months ago that he was becoming short of breath and feeling chest constrictions while exerting himself. After angiography, or pictures of his arteries, were taken, doctors confirmed extensive blockage in the vessels supplying blood to his heart and a strong heart muscle.
Schwartz said that the surgery had been delayed for several days because the former president had been given Plavix, a blood thinner frequently used to reduce symptoms associated with clogged arteries.
"The reason that we waited several days ... he had been placed on a blood-thinning medication as part of his treatment and it was our decision that it would be safest to wait until the medication had decreased to greatly cut down the chance of bleeding during surgery," Schwartz said.
Clinton may have been misled into thinking that his symptoms were caused by acid reflux, Schwartz said, adding that in the past the former president had been put on a cholesterol-reducing medication. Schwartz said Clinton would be put on aspirin, as is typical for heart surgery patients, but Smith said he sees no need for a nurse to tend to him at home.
The doctors also said it's likely the president will be back to his active schedule in short order.
"I would encourage him to resume all activities, including campaigning, as we both deem that it is safe and appropriate in consultation with his entire health care team," Schwartz said.
In bypass surgery, doctors remove a blood vessel from elsewhere in the body and attach it to the heart, detouring blood around blockages. The vessel typically comes from the leg, although doctors sometimes take it from an arm, stomach or chest wall.
In a telephone call Friday evening to "Larry King Live," Clinton said he was "a little scared, but not much."
"I'm looking forward to it," Clinton said of the surgery. "I want to get back. I want to see what it's like to run five miles again."
Clinton and his family issued a statement on the Clinton Foundation's Web site on Sunday, saying they felt "blessed and grateful for the thousands of prayers and messages of good will we have received these past few days." They also expressed thanks that the medical problem was detected in time. The Web site had received more than 30,000 well-wishes by Monday.
According to the American Heart Association, six risk factors often contribute to heart disease: high blood pressure, high cholesterol, diabetes, genetics, smoking and inactivity.
Doctors in the press conference said that in order to prevent future problems, including a possible heart attack, Clinton will have to maintain a low-saturated fat, low-sodium diet.
Parente added that Clinton's observing the South Beach Diet (search) is unlikely to have contributed to his condition. While the South Beach Diet, which cuts out carbohydrates, has been likened to other diets that are more reliant on fat, Parente said the South Beach Diet is heart-friendly.
The hospital where Clinton underwent the procedure is one of the country's premier hospitals for heart surgery, ranked seventh in the nation this year by U.S. News & World Report.
In 2001, New York Presbyterian's Columbia center, where Clinton is being operated on, had the highest death rate in New York state for heart bypass surgeries, according to a state Health Department report — 3.7 percent, or 3.9 percent when adjusted for various risk factors.
But the hospital's death rate for bypasses has dropped each year since then — to 1.9 percent in 2002, 0.8 percent in 2003 and 0.6 percent in the first half of 2004, hospital spokeswoman Myrna Manners said.
Dr. Robert Gallino, a cardiologist and director of vascular interventions at George Washington University, told FOX News that often the rate of death is higher in hospitals like Columbia/Presbyterian, where the best doctors are available to take care of the worst and most extreme cases.
Clinton has blamed the blockage in part on genetics but also said he "may have done some damage in those years when I was too careless about what I ate."
As president, Clinton was an avid jogger but also known for his love of fast food. He has appeared much slimmer since early in the year, when he said he had cut out junk food, started the South Beach Diet and begun a workout regimen.
Clinton had a cancerous growth removed from his back shortly after leaving office, and had a precancerous lesion removed from his nose earlier.
But otherwise, Clinton suffered only the usual problems that often accompany normal aging and a taste for junk food — periods of slightly elevated cholesterol and hearing loss. In 1997, he was fitted with hearing aids, and he also battled allergies.
In her statement, Sen. Clinton said that the family had spent recent days "talking, playing games, and just being with each other." But the former president did not set aside work altogether. On Saturday night, Clinton had a long telephone conversation with Sen. John Kerry (search) on presidential campaign strategy, a Democratic official familiar with the talk who spoke on condition of anonymity said.
The Associated Press contributed to this report.