Only 18 percent of U.S. hospitals now offer angioplasty, and only 5 percent of those hospitals have the staff and facilities available to provide immediate coronary bypass surgery in the event that an emergency develops during angioplasty.

Angioplasty involves threading a balloon-tipped wire through the blood vessels, into the coronary artery, where the balloon expands, compressing the clots against the artery wall. It is one of the standard treatments for blockages of the coronary arteries, which provide blood to the heart muscle.