Less than half of all Americans who undergo non-emergency artery-opening procedures for heart disease get the recommended cardiac stress tests, a study published in today’s Journal of the American Medical Association shows. The American Heart Association and other medical groups recommend the cardiac stress test to determine whether the patient needs the angioplasty. The test is used to measure blood flow to the heart during exercise.

Only 44.5 percent of Medicare patients surveyed in the study had a stress test before the surgery. The results varied by patient characteristics and the age of the doctor performing the PCI. Patients with a previous history of heart disease were less likely to receive a test. In other cases, doctors choose to use another test, called coronary angiography, which uses special dye and X-rays to identify the artery blockages.

One of the reasons for the differing rates of stress testing, the researchers said, is that the guidelines are not as clear as they should be.

“That situation may be clarified by new guidelines expected to be released shortly by the American College of Cardiology, said Dr. Rita F. Redberg, professor of medicine at the University of California, San Francisco and co-author of the study. “The college is about to release appropriateness criteria that say that in such-and-such a situation, a PCI would be appropriate,” she said.

Previous studies have shown that drug therapy performed equally well in treating people with heart disease. The advantages for angioplasty at relieving pain for patients that suffer from chronic chest pain tend to fade over the years and vanish after three years, a study published earlier this year in the New England Journal of Medicine showed.