Los Angeles ? Tens or even hundreds of thousands of Americans are having coronary artery angioplasty and stenting every year when they should be having bypass grafts, and the result is an extra 5,000 or more deaths annually, researchers said Sunday.

Patients and cardiologists frequently prefer angioplasty and the insertion of a stent to keep arteries open because it is quicker and easier, and patients go home sooner and return to work more quickly.

But new data from a major European-American study on more than 1,800 patients show that three years after the procedure, those who got stents were 28 percent more likely to suffer a major event, such as a heart attack or stroke, and 46 percent more likely to require a repeat procedure to reopen arteries. They were 22 percent more likely to die.

“This is one of the strongest studies yet demonstrating that, in advanced coronary disease, bypass has a real patient advantage,” said Dr. Robert Guyton, chief of cardiothoracic surgery at the Emory University School of Medicine, who was not involved in the study.

Coronary-artery bypass grafts, commonly called CABG (pronounced cabbage), were the first treatment for blocked arteries. In the procedure, a blood vessel removed from elsewhere in the body, most often the chest or the leg, is used to bypass the blocked area, providing a new channel for blood to flow to the heart.

Hospital stays generally last five or six days, and the patient can return to work after a few weeks.

In recent years, however, cardiologists have turned more and more to balloon angioplasty, in which a catheter is threaded through a blood vessel in the groin to reach the blockage and a balloon is inflated at the site to compress the plaque. Originally, that was all that was done. Then physicians began inserting bare-metal stents, spring-like devices that hold the artery open.

Hospital stays are typically overnight, and the patient can return to work after a couple of days.