CORRESPONDENCE: LETTER TO THE EDITOR
Diagnostic Accuracy of 64-Slice Computed Tomography Coronary AngiographyA Flawed Comparison
Edward D. Nicol, MD, MRCP*,
James Stirrup, MRCP,
Simon P.G. Padley, FRCP, FRCR and
Michael B. Rubens, FRCR
* Royal Brompton Hospital and Harefield NHS Trust, Sydney Street, London SW3 6NP, United Kingdom (Email: e.nicol{at}rbht.nhs.uk).
We read with interest the recent paper by Meijboom et al. (1) and the corresponding editorial by Nissen (2). We wish to make 3 comments.
First, as with almost all previous validation studies comparing computed tomography coronary angiography (CTCA) with invasive coronary angiography (ICA), significant stenoses are defined as >50% on both quantitative assessment of ICA and visual estimation of CTCA, with the 2 techniques subsequently compared. The major flaw with this approach is that a measurement of 50% on quantitative coronary angiography is the equivalent of a visual stenosis of 70%, and therefore there is a systematic overestimation of stenosis severity by CTCA contributing to the large number of false-positive results. This high false-positive rate is then used to highlight the shortcomings of CTCA.
The argument for the use of a 50% stenosis cutoff for CTCA is due to the limited spatial resolution of CTCA as discussed in the Nissen editorial (2). However, the majority of symptomatic patients show stenoses well in excess of 70%, and our own previous work clearly shows an increase in the positive predictive value of CTCA as compared with single-photon emission computed tomography when using a visual cutoff of 70% (3). Furthermore, our own validation data demonstrate that this is also true for comparison with ICA. In this setting, the associated increase in specificity associated with using a 70% cutoff comes at a cost of significantly reduced sensitivity whilst delivering an identical area under the curve.
So, although we agree with Nissen's view (2) that there is no proven benefit for multimodality noninvasive assessment of coronary artery disease, the targeted use of a combined approach for patients with apparent lesions of 50% to 69% on CTCA would allow a more reliable determination of significance in these intermediate lesions.
Second, we absolutely share the view that the rapid proliferation of CTCA and so called "weekend accreditation" is not an appropriate strategy for high-quality patient care and therefore would argue that both more rigorous accreditation is needed and further research into the most appropriate use of the technology is paramount.
Third, we would agree that the current research on this technology does not support its use beyond the exclusion of significant coronary artery disease. Efforts should now focus on answering some of the more fundamental issues limiting the clinical use of CTCA rather than on the exploration of the latest new iteration of this seductive technology. We would agree that further real-world studies are required. These would include assessing the use of a visual 70% stenosis cutoff for defining significant lesions, with the use of a targeted functional testing for those with intermediate lesions (50% to 69%). We would also support longer-term studies assessing outcome data in patients evaluated with this technology compared with conventional assessment. However, we should not write off CTCA, because there are few medical tests that reliably offer a negative predictive value in excess of 90%, confirmed again by this study.
 |
References
|
|---|
1. Meijboom WB, Meijs MF, Schuijf JD, et al. Diagnostic accuracy of 64-slice computed tomography coronary angiography: a prospective, multicenter, multivendor study J Am Coll Cardiol 2008;52:2135-2144.[Abstract/Free Full Text]2. Nissen SE. Limitations of computed tomography coronary angiography J Am Coll Cardiol 2008;52:2145-2147.[Free Full Text] 3. Nicol E, Stirrup J, Reyes E, et al. 64-MDCT coronary angiography compared with myocardial perfusion scintigraphy in patients with low to intermediate likelihood of coronary artery disease J Nuc Cardiol 2008;15:311-318.[CrossRef]
Related Article
-
Reply
- W. Bob Meijboom, Matthijs F.L. Meijs, Joanne D. Schuijf, Maarten J. Cramer, Nico R. Mollet, Carlos A.G. van Mieghem, Koen Nieman, Jacob M. van Werkhoven, Gabija Pundziute, Annick C. Weustink, Alexander M. de Vos, Francesca Pugliese, Benno Rensing, J. Wouter Jukema, Jeroen J. Bax, Mathias Prokop, Pieter A. Doevendans, Myriam G. Hunink, Gabriel P. Krestin, and Pim J. de Feyter
J. Am. Coll. Cardiol. 2009 53: 1825-1826.
[Full Text]
[PDF]
|
Top
References