In a bypass operation, doctors move healthy segments of blood vessels from other parts of the body to create detours around clogged arteries supplying blood to the heart. Angioplasty repairs the damage through a tube pushed through a blood vessel. A tiny balloon is inflated to flatten the clog and a mesh scaffold, a stent, is placed to prop the artery open.

Researchers compared these approaches using Medicare records on 190,000 patients with two or three clogged arteries — the largest study ever of this issue. Death rates were similar one year after either treatment. But after four years, nearly 21 percent of the angioplasty patients had died versus about 16 percent of those who had bypass surgery.

Doctors say differences in the overall health of people who had surgery versus the less drastic procedure could account for some of the results. They say angioplasty remains a good and safe option for many people.