Hybrid Myocardial Perfusion SPECT/CT Coronary Angiography and Invasive Coronary Angiography in Patients With Stable Angina Pectoris Lead to Similar Treatment Decisions

Feb 28, 2013
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Authors:
Schaap J, de Groot JA, Nieman K, et al.
Citation:
Heart 2013;99:188-194.
Summary By:
Troy M LaBounty, MD, FACC

Study Questions:

Does evaluation of combined single-photon emission computed tomography (SPECT) and coronary computed tomography angiography (CCTA) findings result in a difference in revascularization rates, as compared to evaluation of combined SPECT and coronary angiography (CA)?

Methods:

This study prospectively evaluated 107 patients with stable angina and intermediate-high pretest probability of coronary artery disease, who underwent hybrid SPECT/CCTA imaging prior to CA. A panel of one cardiothoracic surgeon and two interventional cardiologists evaluated cases based on SPECT and CCTA findings, and made a decision about revascularization strategy; at least 4 weeks later, the panel reviewed SPECT and CA images and made a separate decision on treatment strategy. Revascularization strategy was compared between imaging by SPECT/CCTA and SPECT/CA.

Results:

Mean age was 63 ± 10 years; 69% were male. Mean radiation doses were 4.2 ± 1.0 mSv, 6.8 ± 2.4 mSv, and 10.5 ± 4.9 mSv for CCTA, SPECT, and CA, respectively. Reversible defects by SPECT and stenosis >50% by CCTA were observed in 57% and 59% of patients, respectively. Matched SPECT/CCTA findings were noted in 37% of patients, whereas unmatched findings were observed in 41% of individuals, and the remaining had normal findings on both SPECT and CCTA. Agreement for revascularization was observed for both SPECT/CCTA and SPECT/CA in 50 individuals (47%), with agreement for no revascularization observed in 48 individuals (45%); overall, agreement was observed in 92% of patients. In cases without agreement between strategies, SPECT/CCTA alone suggested an indication for revascularization in four patients (4%), whereas SPECT/CA suggested an indication in five patients (5%).

Conclusions:

A diagnostic approach using combined SPECT/CCTA imaging results in similar rates of recommended revascularization, as compared to an approach using combined SPECT/CA.

Perspective:

This study finds that combined CCTA/SPECT versus SPECT/CA imaging results in comparable rates of patients meeting indications for revascularization, with the former strategy associated with significantly less exposure to ionizing radiation. However, the clinical relevance of this study is somewhat limited, as it tests a hybrid imaging approach that is not commonly practiced, and may be associated with increased cost and radiation exposure. Future research is needed to determine indications for which hybrid imaging may be clinically appropriate.

Keywords: Radiation, Constriction, Coronary Artery Disease, Coronary Angiography, Tomography, Diagnostic Imaging, Radiopharmaceuticals, Probability


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