Title: Diagnostic Accuracy and Clinical Utility of Noninvasive Testing for Coronary Artery Disease
Topic: Noninvasive Cardiology
Date Posted: 5/28/2010
Author(s): Weustink AC, Mollet NR, Neefjes LA, et al.
Citation: Ann Intern Med 2010;152:630-639.
Clinical Trial: No
Study Question: What is the relative accuracy and clinical utility of stress testing and computed tomographic coronary arteriography (CTCA) for identifying patients who require invasive coronary angiography (ICA)?
Methods: This observational study was conducted in patients referred for chest pain in a single academic center. In 2004 to 2006, 297 patients underwent stress testing with electrocardiogram (ECG) and nuclear imaging (exercise or pharmacologic), CTCA, and ICA. In 2006 to 2008, all 220 patients who met eligibility criteria underwent stress testing and CTCA. The 141 patients with a normal stress ECG and imaging and normal CTCA were considered to have no coronary disease. Diagnostic accuracy of stress testing and CTCA was compared with ICA; pretest probabilities of disease by Duke clinical score; and clinical utility of noninvasive testing, defined as a pretest or post-test probability that suggests how to proceed with testing (no further testing if ≤5%, proceed with ICA if between 5% and 90%, and refer directly for ICA if ≥90%). For both CTCA and ICA, significant coronary stenosis was defined as >50% luminal narrowing in all coronary segments.
Results: Mean age was 58.9 years, and 61% were men; chest pain was typical angina in 43.1%, atypical angina in 21.5%, and nonangina in 35%. Significant obstructive CAD on ICA was present in 53%, nonsignificant in 11%, and no CAD in 35%. Stress testing was not as accurate as CTCA; CTCA sensitivity approached 100%. In patients with a low (≤20%) pretest probability of disease, negative stress test, or CTCA results suggested no need for ICA. In patients with an intermediate (20-80%) pretest probability, a positive CTCA result suggested need to proceed with ICA (post-test probability, 93%), and a negative result suggested no need for further testing (post-test probability, 1%). Physicians could proceed directly with ICA in patients with a high (≥80%) pretest probability (91%).
Conclusions: The authors concluded that CTCA seems most valuable in patients with intermediate pretest probability of disease, because the test can distinguish which of these patients need ICA. These findings need to be confirmed before CTCA can be routinely recommended for these patients.
Perspective: The authors correctly commented that referral and verification bias might have influenced findings; and stress testing provides functional information that may add value to that from anatomical (CTCA or ICA) imaging. The study does little to add to the decision process for invasive coronary arteriography, particularly in the post-COURAGE trial era, but does add to the body of literature that CTCA can be very useful in the evaluation of chest pain. If it were not for relatively high radiation exposure (8-13 mSv), it would be the diagnostic tool of choice both for accuracy and ability to identify plaque burden that is not hemodynamically significant. Melvyn Rubenfire, M.D., F.A.C.C.
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