CORRESPONDENCE: LETTER TO THE EDITOR
Reply
Robert C. Hendel, MD, Chair* Writing Group for RNI Appropriate Use Criteria,
Michael J. Wolk, MD, Chair Appropriate Use Criteria Task Force
* Director of Cardiac Imaging, University of Miami Miller School of Medicine, 1120 Northwest 14th Street, Suite 118, Miami, Florida 33136 (Email: rhendel.cardio{at}yahoo.com).
We greatly appreciate the comments of Dr. Sethi and colleagues regarding the use of radionuclide imaging (RNI) in an asymptomatic but high-risk patient, such as one with diabetes mellitus, which constitutes one of the indications noted in the recently published RNI appropriate use criteria (AUC) (1). Their letter correctly describes the low event rate noted in the DIAD (Detection of Ischemia in Asymptomatic Diabetics) study (2). Furthermore, information from the BARI-2D (Bypass Angioplasty Revascularization Investigation in Type 2 Diabetes) study (3), as well as that from the COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) study (4), fails to support the benefit of revascularization, at least with regard to major cardiovascular events. At the present time, diabetic patients are still considered by clinical practice guidelines to be a high-risk/coronary artery disease-equivalent cohort, although that may change in the future. However, neither the BARI-2D study nor the DIAD study data were available at the time of the rating for the radionuclide AUC. Additionally, both of these trials had a highly selected population of diabetic patients, which may not be representative of the risk for cardiovascular events in the general diabetic population.
Perhaps more importantly, the method for development of AUC is rigorous and does not permit alteration of the final scores and classification by the technical (rating) panel. Additionally, the AUC do not state that testing "must" be performed, only that it is reasonable given the clinical scenario and the available medical knowledge/experience. AUC are therefore not equivalent to a Class I clinical practice guideline.
Although the COURAGE nuclear substudy was underpowered to detect differences in treatment approaches, those subjects who experienced a reduction of ischemia on single-positron emission computed tomography myocardial perfusion imaging had a superior outcome, although this difference was lost when further risk adjusted. Therefore, we agree with the opinion of Dr. Sethi and colleagues that "routine RNI can be of use, if we can identify a subgroup of asymptomatic patients ... who can benefit from revascularization." This thereby allows the indication to be considered "appropriate" or reasonable in the parlance of AUC.
We agree that, in light of the newer trials, it may not be accurate to place patients with only the risk factor of diabetes into the high-risk category. However, based on available information, we believe that the rating by the technical panel was reasonable. We await additional information on the best way for risk assessment of patients and will certainly consider revising the AUC as new evidence becomes available. Thank you for your thoughtful comments.
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References
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1. Hendel RC, Berman DS, Di Carli MF, et al. ACCF/ASNC/ACR/AHA/ASE/SCCT/SCMR/SNM 2009 appropriate use criteria for cardiac radionuclide imaging: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, the American Society of Nuclear Cardiology, the American College of Radiology, the American Heart Association, the American Society of Echocardiography, the Society of Cardiovascular Computed Tomography, the Society for Cardiovascular Magnetic Resonance, and the Society of Nuclear Medicine J Am Coll Cardiol 2009;53:2201-2229.[Free Full Text]2. Young LH, Wackers FJ, Chyun DA, et al. DIAD Investigators Cardiac outcomes after screening for asymptomatic coronary artery disease in patients with type 2 diabetes. The DIAD study: a randomized controlled trial. JAMA 2009;301:1547-1555.[Abstract/Free Full Text] 3. Frye RL, August P, Brooks MM, et al. BARI 2D Study Group A randomized trial of therapies for type 2 diabetes and coronary artery disease N Engl J Med 2009;360:2503-2515.[CrossRef][Medline] 4. Boden WE, O’Rourke RA, Teo KK, et al. COURAGE Trial Research Group Optimal medical therapy with or without PCI for stable coronary disease N Engl J Med 2007;356:1503-1516.[CrossRef][Medline]
Related Article
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Is Appropriate Use Criteria for Cardiac Radionuclide Imaging in Asymptomatic Diabetic Patients Evidence Based?
- Ankur Sethi, Amol Bahekar, and Rohit Bhuriya
J. Am. Coll. Cardiol. 2010 55: 260.
[Full Text]
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