Can American doctors say “No” to an aggressive and high-tech treatment they’re used to providing even when it turns out a less heroic and cheaper one works just as well?

It’s an important question.

The affordability of American medical care in the future will depend, in part, on the ability of physicians to simplify and economize, which are two things they’ve never been good at. With national health expenditures amounting to $2.6 trillion a year — 45 percent of it paid by government — prosperity and political stability may also be at stake.

Different versions of this question are behind the debate about whether women should get mammograms annually or every other year; whether cancer patients should be denied the expensive and usually ineffectual drug Avastin; and whether curative surgery should be attempted in most cases of prostate cancer.

“Medicine is often not agile in incorporating new knowledge into practice, and as a result many patients are treated in anachronistic ways,” said Harlan M. Krumholz, a cardiologist and outcomes researcher at Yale School of Medicine. “The health-care system of the future must be able to adapt more quickly, and also have a way to evaluate how the changes it makes actually affect people.”

The question is being posed to cardiology — the medical specialty that treats heart disease, the nation’s leading cause of death — in a most interesting way.

At issue is how to treat about 500,000 Americans who each year develop “stable angina,” which is chest pain that occurs in predictable fashion and is caused by blockages in the heart’s coronary arteries. There are two common treatment approaches. One is angioplasty with stenting, in which a catheter is threaded into the narrowed artery, which is then propped open with a tube made of metal mesh. The other is medication and changes to lifestyle.

In many people’s minds, this issue is settled. The answer came in a $33.5 million clinical trial called COURAGE, whose results were announced five years ago.

In that experiment, 2,300 people with stable angina were given “optimal medical therapy” consisting of aspirin, beta blockers and statin drugs, along with help losing weight, quitting smoking and keeping blood pressure under control. Half were also randomly assigned to get angioplasty and stenting. (The varieties of the procedure are known collectively as “percutaneous coronary intervention,” or PCI.)

After nearly five years, the rate of heart attack and death in the two groups was essentially the same: 18.5 percent in those getting only medical therapy and 19 percent in those who also got stents. The only difference between the groups was that people getting stents were slightly more likely to be angina-free (66 percent vs. 58 percent after one year).

The financial stakes

Stable angina isn’t the main reason Americans get angioplasty and stents. It accounts for about 30 percent of patients receiving the procedure. Most who get it have rapidly worsening chest pain (“unstable angina”) or are having a heart attack.

Consequently, the results of the COURAGE study weren’t going to empty out cardiac procedure suites. Nevertheless, the amount of money in play was — and is — considerable.

A PCI procedure costs about $17,000. More than 500,000 are done each year in this country. Medicare pays for about 350,000 a year; this treatment alone accounts for at least 10 percent of Medicare’s total spending growth since the mid-1990s.

COURAGE sent shock waves through the cardiology community. There were immediately efforts to refine or discredit it. Some commentators said it was old news, citing previous smaller studies that showed the same thing. Others pointed to subgroups of patients (women, people with severely limited coronary blood flow) that seemed to do better with the more aggressive treatment.

But the message has remained clear: Cardiologists are jumping to angioplasty and stenting too quickly in lots of patients.

“The use of PCI in certain settings can be lifesaving; however, PCI is clearly being performed more often than appropriate,” cardiologist Rita F. Redberg of the University of California at San Francisco wrote last fall in the Archives of Internal Medicine.

A small shift

In the half-decade since the study came out, things have changed a little. But not much.

The annual number of PCI procedures in the United States has gone down slightly. How much of that is a change of practice and how much a consequence of the steady 50-year decline in heart disease isn’t clear.

It may be that fewer people are getting PCI for stable angina now. That was the case in a registry of 26,000 patients in northern New England, where that diagnosis was given in 21 percent of procedures in the year before COURAGE was published but in only 16 percent in the years just after it. Whether that reflects a national trend also isn’t known.

On the other hand, physicians’ willingness to give “optimal medical therapy” a real try before taking a patient to the procedure room hasn’t budged. A study published last year showed that before COURAGE, 44 percent of patients with stable angina getting PCI had fully attempted drug-and-lifestyle treatment before turning to the procedure. After COURAGE, that went up one click, to 45 percent.

Why hasn’t there been more change?

“It’s easier to get people to start something new than to give up something they’ve been doing for a long time,” said Mark A. Hlatky, a cardiologist at Stanford University. Change also comes more readily if something causes actual harm rather than just doesn’t do any good.

(That was the case when studies in the 1950s showed that routinely giving extra oxygen to premature babies was causing thousands of them to go blind. Pediatricians wised up quickly.)

As a rule, “nothing changes that fast in medicine,” said Hlatky, who writes widely on health policy. “It’s not enough to just prove that something works. There’s a whole secondary task of getting it into practice.”

The problem, though, may be deeper than that. It may lie in the culture of American medicine, which with little exagerration can be summed up by the sentence: “Don’t just stand there, do something!”

When cardiologists see a big blockage in an artery during cardiac catheterization, most want to go after it. Hlatky and another cardiologist, Eric J. Topol, of Scripps Reseaerch Institute in California, have dubbed it the “oculostenotic reflex”: Seeing (“oculo”) a narrowed (“stenotic”) vessel leads to a reflex to open it — even if there’s no evidence that doing so will prevent a heart attack or save a life.

A year after the COURAGE study came out, Rita F. Redberg and Grace A. Lin of the University of California at San Francisco held three focus groups of cardiologists to talk about the study results. Regardless of what type of practice they were in — private, academic, managed-care — many said they simply had a hard time putting the study’s results into practice because it clashed so much with their beliefs in the value of PCI. Many said that patients expect and want interventions. Some talked about the fear of lawsuits.

“It really spoke to how difficult it can be to change established practice even with good data,” said Redberg, who is a cardiologist herself.

The physicians also talked about their emotions. A big one was the regret they would feel if they didn’t offer angioplasty to a patient and then something bad happened.

“They consistently told us that an error of commission was better than an error of omission,” Redberg said. That was echoed in a survey of 500 cardiologists last year in which a majority said it was “easier to accept” the death of a patient getting an angioplasty than the death of a patient sent home without the procedure.

The Obama health-care law — if it survives this year’s election and Supreme Court review — has many incentives aimed at making doctors do a better and more economical job.

Physicians may get more money if they adhere to guidelines (unless there’s a good reason not to). Medical organizations may get a “bundled payment” for a patient’s care, giving them reason to try cheaper, equally good therapies first. Quality ratings — and the status that comes with them — may be linked to following “best practices.”

The federal government also now officially sponsors the emerging field of “comparative effectiveness” research, which is built on the assumption that doctors can, and should, change their practices based on evidence and also what patients actually want.

It seems clear, though, that it will take more than incentives and new studies to make lessons like the one taught by COURAGE stick. It will require changing minds.