CT angiography after positive stress tests is cost-effective
MedWire News: Non-invasive computed tomography angiography (CTA) is a cost-effective alternative to invasive cardiac catheterization in patients who have a positive stress test result, no other symptoms, and a less than 50% chance of having significant coronary artery disease (CAD), report researchers.
Ethan Halpern (Thomas Jefferson University, Philadelphia, Pennsylvania, USA) and colleagues 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.
They note that patients who test positive for CAD on stress tests but show no other symptoms of the disease are often referred for diagnostic catheter angiography, but very few have CAD.
The researchers therefore investigated whether referring such patients to CTA may be a cost-effective alternative.
Costs for coronary CTA and diagnostic catheterization were obtained from the 2009 physician Medicare fee schedule, while sensitivity, specificity, and radiation dose were obtained by literature review.
The average cost to Medicare was US $508 [€382] for coronary CTA and $2,948 [€2,216] for cardiac catheterization.
Halpern et al report in the American Journal of Roentgenology that cost reduction with coronary CTA depends on the prevalence of CAD, but overall costs are reduced compared with cardiac catheterization as long as the prevalence is less than 85%.
They add: “At a 50% prevalence of CAD, performing coronary CTA before cardiac catheterization results in an average cost saving of $789 [€593] per patient with a false-negative rate of 2.5% and average additional radiation exposure of 1–2 mSv.”
The false-negative rate with this strategy compares favorably with the false-negative rate of stress testing, the researchers note.
They comment: “We do not recommend coronary CTA when the probability that the patient has significant CAD is greater than 50%, because these patients are more likely to have calcified CAD, which is difficult to evaluate with coronary CTA.”
However, “for a patient at low risk who has no symptoms and has a positive stress test result, our results suggest that preliminary coronary CTA rather than direct triage to cardiac catheterization is a cost-effective alternative,” they conclude.
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By James Taylor