Outside of heart attacks, doctors are often too quick to use a common $20,000 procedure to treat patients suffering from coronary artery disease, a new study suggests. About 600,000 angioplasty procedures, which almost always involve placement of a stent, are done in the U.S. each year. Roughly 70% of these procedures are performed on patients suffering symptoms of a heart attack and aren't medically controversial. But the remainder are done on stable patients who are suffering mild symptoms or no symptoms at all. Of those, 50% are deemed appropriate, 38% uncertain and 12% inappropriate, the report says. The results, published in the Journal of the American Medical Association Tuesday, come amid rising concern about the overuse of big ticket medical technology. Such concerns are rising not only in cardiology, but in other major specialties as state and federal governments and health insurers seek to contain healthcare costs.