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.