A common heart bypass surgery technique appears to raise patients' risk of dying or suffering a heart attack in the three years following the procedure, according to a study published Thursday in the New England Journal of Medicine.

For decades, the method — in which a leg vein is cut up and moved to the chest to create detours around clogged heart arteries — involved a long incision, sometimes from groin to toe, that was painful, left a big scar and often led to infections as well as a long hospital stay.

About 13 years ago, doctors altered the procedure to make it less invasive. The new method involved making small "porthole" cuts, and using a tiny scope and tools to pull the vein out through the small openings.

While the less invasion technique spared patients pain and problems upfront, they were significantly more likely to die, suffer a heart attack or need another artery-opening procedure in the three years after surgery. The likely cause is that the vein suffers damage from being pulled out and doesn't hold up well over time.

More than nine per cent of people whose veins were removed this way died or suffered a heart attack in the following three years, compared to fewer than eight percent of those who underwent the traditional method.

The research involved 3,000 patients at more than 100 sites in the United States who were part of another study for an experimental drug. The results are not considered definitive because its primary aim wasn't to evaluate the leg artery removal technique. However, it is the largest study, with the longest followup, to look at this method.

'This is a very worrisome finding'

The results surprised doctors.

The study leader, Dr. John Alexander of Duke University Medical Center, called it "a wakeup call" to rethink the approach.

While more research is needed to confirm the results, doctors should use the technique more sparingly or handle the vein more carefully when they do pull it out, said Dr. Timothy Gardner, a heart surgeon at Christiana Care Health Services in Wilmington, Del.

"This is a very worrisome finding," he said.

The results are a cautionary tale about rushing to adopt approaches that seem better for patients but may have hidden dangers, said Dr. Robert Guyton, cardiothoracic surgery chief at Emory University Hospital in Atlanta.

"There is a big push, both from patients and from cardiologists, for small incisions, minimally invasive techniques," he said. "That push sometimes pushes surgeons to adopt these types of procedures that have not been vetted as well as they might be."

With files from The Associated Press