After more than a decade-long decline, is heart bypass surgery poised for a comeback?

Some doctors say it may be time to give bypass operations a second look. They include even some cardiologists who specialize in the far more popular alternative — using stents to keep coronary arteries open.

No one is predicting a sudden surge back to bypass, which is still a far more invasive and initially riskier way to treat plaque-clogged heart arteries, a condition that afflicts millions of Americans.

But in light of new safety concerns over the long-term risks of stents, as well as accumulating data indicating that the sickest heart patients may live longer if they receive bypass surgery instead, some well-known stent specialists say the pendulum may have swung too far away from bypass surgery.

“We as cardiologists have probably pressed forward on stent technology a little faster than we should have,” said Dr. Kirk Garratt, the director of research into stents and related heart therapies at Lenox Hill Hospital in New York, one of the nation’s leading stenting centers.

It is a remarkable acknowledgment, considering the medical and financial stakes in play. In the last decade, the number of bypass surgeries in this country has fallen by a third — to about 365,000 last year. Meanwhile, the number of patients receiving stents has soared, to nearly a million in 2006.

To some extent, the stent preference has been propelled by patients themselves, who have an understandable aversion to major surgery.

“Most of the time that I recommend bypass surgery, the patient begs me to put in stents instead,” said Dr. Ralph Brindis, senior cardiovascular adviser for the network of Kaiser Permanente hospitals and clinics in Northern California.

But stents are also big business, with powerful advocates like Boston Scientific and Johnson & Johnson, whose stent sales totaled about $2.9 billion last year. They, along with competitors trying to catch up, have invested heavily in expanding the use of stents.

And cardiologists, the specialists who are most likely to diagnose artery disease, are in many cases also the doctors who implant stents. Their judgment heavily influences which patients get referred to surgeons.

Meanwhile, as Medicare and other insurers have curbed their payments for bypass surgeries, the cost of stenting has risen with the introduction of newer devices. Surgery and stent procedures are now comparably priced for patients with multiple blockages — an average of around $30,000, according to the American College of Cardiology and the American Heart Association. Both procedures are generally covered by insurers.

As a result of these forces, surgeons, once the kings of the cardiac ward, have seen their annual incomes dwindle. They averaged $425,000 last year, down from $1.02 million in 1990, after adjusting for inflation, according to John O. Goodman, a leading consultant to cardiovascular doctors.

Meanwhile, Mr. Goodman said, the average income of an interventional cardiologist, as a stent specialist is known, has risen to $550,000 from an inflation-adjusted $392,000 in 1990.

But Mr. Goodman says he expects the number of bypass surgeries to begin rising this year, although he declines to forecast by how much.

What has changed most recently in the stents-versus-surgery calculus is new evidence that surfaced in clinical trials last year. The data disclosed a previously undetected risk with stents, which are tiny mesh cylinders that are placed in arteries via filament-thin catheters threaded from a tiny incision in the thigh.

The new evidence showed that patients receiving the most popular form of stents — ones coated with drugs to reduce the likelihood that the artery will close again — have a slight risk of forming potentially fatal blood clots in the stents long after they have been implanted.

That changed the cost-benefit calculus of stents versus surgery in cases where patients have multiple blockages in two or more arteries or have other complications.

Bypass surgery is the recommended treatment for such patients, according to the guidelines of the American Heart Association and the American College of Cardiology. But some doctors say too many patients never hear about those recommendations from their cardiologists.

A joint committee of the heart association and cardiology society expects to release new guidelines within the next month that could clarify the proper boundary between stenting and surgery, according to Dr. Sydney C. Smith Jr., the head of the committee.

One controversial factor in such assessments is the accumulating data suggesting that surgery may help the sickest heart patients live longer.