Arthur Agatston, the South Beach diet doctor, came to town last week and, in between bites of filleted fish, he was trying to persuade me that his patients rarely have heart attacks anymore.

As he is quick to tell almost anyone — as he told me before we had even sat down for our Greek lunch — he is an accidental diet doctor. By training, he’s a cardiologist. He spent 20 years doing research and seeing patients in Miami before his little nutrition manifesto was published in 2003. It and its various spinoffs have since sold close to 20 million copies.

But Dr. Agatston still spends much of his time as a working cardiologist. After the first book came out, he opened a private practice where he treats everyone from locals who knew him when he was just another doctor to wealthy South Americans who fly in to see the famous South Beach doctor.

The practice has 2,800 patients, and, as best as Dr. Agatston can recall, only three of them had a heart attack last year. “Heart attacks are essentially disappearing from my practice,” he says in his Long Island-tinged accent.

It is a fairly stunning claim, the sort of claim that you might expect to hear from someone who knows how to sell a product. If Dr. Agatston were to do a thorough review of his files, I wonder if he might come across a few more heart attacks, perhaps among patients he doesn’t see regularly.

But his larger point is a perfectly good one: we now know an enormous amount about how to prevent heart attacks, with powerful drugs like statins, smoking cessation, exercise and diet. With the right preventive care, people can cut their risk of a heart attack by up to 80 percent, cardiologists estimate.

“We have made major improvements in prevention,” Dr. Gregg W. Stone, the director of cardiovascular research at Columbia University, says. “But it’s difficult. It takes frequent visits, a close relationship between a physician and a patient and a very committed patient.”

Which is exactly the atmosphere Dr. Agatston’s practice tries to create. Nurses there give patients specific cholesterol goals to meet and help them deal with the side effects of the drugs they are taking. A nutritionist, Marie Almon, meets with patients frequently enough to discuss real-life issues like how to stick to a high-fiber Mediterranean diet even on a cruise or a business trip.

There is only one problem with this shining example of a medical practice: it is losing money.

See, preventive medicine just doesn’t pay in the current American medical system. “The time we spend with patients — we get rewarded almost zilch,” Dr. Agatston says. Or as Dr. Valentin Fuster, a former president of the American Heart Association, puts it: “There is no incentive at all. It’s a disaster.”

This is obviously an exciting time for health care reform. In California and Massachusetts, state officials have announced plans to provide universal health insurance. Last week, the head of the Business Roundtable, a major corporate lobbying group, and Andy Stern, a union leader, held a news conference together to call for universal coverage. President Bush devoted a big part of last night’s State of the Union address to his own health insurance ideas. The push to reduce the number of uninsured, now approaching 50 million, is long overdue.

But a lack of insurance is only one of the two huge problems with health care. The other is the perverse system of incentives that nudges doctors and patients toward expensive tests and procedures when cheaper preventive measures might actually produce better results. Partly as a result, costs are rising rapidly for the 250 million people who do have insurance.

In cardiac care, nuclear scans and invasive procedures like bypass surgery bring in the money. Medicare alone paid almost $15 billion, or about 5 percent of its total budget, for bypasses, stents and other invasive cardiology in 2005, according to Jonathan Skinner of Dartmouth. Yet for many patients, there is no scientific evidence that stents or surgery prolong life.

Dr. Agatston doesn’t need Medicare reimbursements to make a living. His books, the latest being “The South Beach Heart Program,” have given him “an outside income,” as he delicately puts it. “I can afford to be holier than thou,” he says.

Absent a wealthy patron, many other clinics that focus on preventing heart disease are struggling to survive, Dr. Richard Pasternak, a Harvard Medical School cardiologist and Merck & Company executive, says. Family doctors, doctors who treat back pain and doctors who treat diabetes all face similar challenges.

It’s important to note that the economic gains from preventive care are sometimes exaggerated. Sadly, the cheapest patients are often the ones who receive no care whatsoever, because many die before they reach their medically expensive golden years.

But the political case — the moral case — for prevention is unassailable. And to the extent that drugs and lifestyle changes replace surgery, rather than merely supplement it, preventive care can help pay for itself.

Given the way the universal insurance movement has taken off, the most likely path to reform probably runs through local governments or other pilot programs, and some of this is beginning to happen.

Humana, the insurer, and Dr. Fuster will soon begin studying 6,000 high-risk patients, in part to get a better understanding of how they can be persuaded to take the preventive steps they should be taking. Medicare, meanwhile, is experimenting with some pay-for-performance stipends for doctors.

“We still pay more when patients have more complications and get more services than when they get better results,” Dr. Mark McClellan, Medicare’s former director, told me recently.

The prevention push is still waiting for its Massachusetts moment — a signature event to make it a topic of national conversation, as Massachusetts’s health insurance plan did for universal coverage last year. Dr. Agatston, who does have a track record of getting people’s attention, has one idea.

“My dream has been to go to a corporation and say, ‘Have all your executives and all your high-risk employees come to our practice, and if they hit our goals and still have a heart attack, we’ll give you a million dollars,’ ” Dr. Agatston said. “My wife and our lawyers say, ‘You can’t do that!’ But that’s frankly my dream.”

Any takers?