The study was published in the May 2010 issue of the American Journal of Roentgenology (AJR). CAD is a narrowing of the blood vessels that supply blood and oxygen to the heart. If left untreated, it can lead to a heart attack. "Patients with positive stress test results but no heart-related symptoms, as well as patients with a positive stress test with atypical chest pain often receive referrals for cardiac catheterization for the evaluation of CAD,” said the study's lead author, Ethan J. Halpern, M.D., professor, department of radiology at Jefferson Medical College (Philadelphia, PA, USA), and director, cardiac CT at Thomas Jefferson University Hospital. "Coronary CTA is an alternative, noninvasive diagnostic imaging test that can be used to effectively triage these patients.”

The study compared the false-negative rates, false-positive rates, costs, and radiation exposure of direct referral of patients for cardiac catheterization with the values associated with performing coronary CTA before catheterization. "At a 50% prevalence of CAD, we found that performing coronary CTA before cardiac catheterization results in an average cost saving of US$789 per patient with a false-negative rate of 2.5% and average additional radiation exposure of 1 mSv - 2 mSv, which is minimal,” said Dr. Halpern.

According to the study results, when a patient with an expected CAD prevalence less than 85% is found to have a positive stress test result, coronary CTA is a less expensive alternative to direct performance of cardiac catheterization. Recent studies have demonstrated that diagnostic cardiac catheterization of patients with atypical symptoms will demonstrate significant CAD less than half of the time. If the pretest probability of CAD is low, the coronary CTA findings are more likely to obviate cardiac catheterization and thereby reduce both the cost and effective radiation dose of the workup.

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