Doctors often order heart test but no disease is found (USA)

"A big study says most patients without known heart disease who undergo coronary angiography don't have clogged arteries after all. In such patients angiograms reveal coronary disease only 40 percent of the time. Worse yet, another 40 percent have essentially clear coronaries. The upshot? Medicine's definitive test for diagnosing heart disease doesn't do a very good job in about 200,000 Americans who get it every year - at about $2,500 a pop. The results suggest the test may be used too often. To do an angiogram, or cardiac catheterization, doctors thread a thin tube from the groin up into the coronary arteries. Injecting a dye shows on x-rays whether arteries are gunked-up or clear. More than a million Americans get angiograms every year. One in five angiograms involves a patient without known heart disease - and often no symptoms. The new data come from the biggest study of the question so far - encompassing 400,000 patients with unknown coronary-artery status prior to their angiograms. It draws from a database of the American College of Cardiology, which funded the project. The findings were published in the current New England Journal of Medicine