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CCTA vs. Nuclear Stress for Chest Pain
Study Questions:
Does coronary computed tomography angiography (CCTA) or stress radionuclide myocardial perfusion imaging (MPI) provide superior selection of patients for invasive angiography and decreased length of stay?
Methods:
The investigators conducted a single-center unblended randomized controlled trial among 400 patients admitted to a telemetry unit for evaluation of chest pain who were determined to require some form of noninvasive imaging. Patients were randomized 1:1 to CCTA or stress MPI. All patients had negative electrocardiogram (ECG) or serum biomarkers for acute ischemia. All subjects had at least one intermediate risk characteristic for death or myocardial infarction in the short term: pain more than 20 minutes, exertional pain arising within past 2 weeks, age >70 years, elevation of troponin T below diagnostic threshold, and/or nonspecific ECG changes. Patients with recent CCTA, MPI, or cardiac catheterization or with contraindications to either CCTA or MPI were excluded. CCTA was performed on a 64-row CT scanner. Stress MPI was performed with either Bruce treadmill exercise or with adenosine or regadenoson vasodilator stress. Attenuation correction was used for MPI. All subjects had rest/stress imaging with either Tl-201/Tc99m-sestamibi or with Tc99m-sestamibi alone. The primary outcome was catheterization not leading to revascularization within 1 year. The secondary outcome of length of hospital stay was computed from randomization to discharge. Subjective patient experience and radiation exposure were also assessed.
Results:
There were no differences in the rate of cardiac catheterization within 1 year between CCTA and MPI (n = 30 vs. n = 32, p = 0.89). More than one half of these did not have revascularization (n = 15 for CCTA and n = 20 for MPI, p = 0.44). Even among significantly abnormal scans, 5 of 20 CCTA patients and 16 of 31 MPI patients did not have revascularization (p = 0.08). Median length of stay was marginally lower in the CCTA group (28.9 vs. 30.4 hours, p = 0.057). Nine CCTA patients and 15 MPI patients died or had nonfatal major adverse cardiovascular events during approximately 40 months of follow-up (p = 0.29). Radiation doses for CCTA were significantly lower than for MPI (9.6 mSv vs. 27 mSv, p < 0.001). Although, overall patient experience scores were comparable for the two tests, more MPI subjects rated their experience as “OK” or worse (p = 0.038).
Conclusions:
CCTA and MPI result in similar diagnostic yield and time to discharge. However, compared with MPI, CCTA was associated with less radiation burden and a more positive patient experience.
Perspective:
This study adds to the literature regarding the evaluation of acute chest pain. Two prior randomized controlled trials (ROMICAT2 and ACRIN-PA) focused on lower-risk patients recruited from the emergency department. The patients in this study were considerably higher risk, as evidenced by the higher event rates seen in follow-up. The equivalence of CCTA and MPI for diagnostic yield is reassuring, although anticipated decreases in time to discharge were not seen. This is particularly surprising, as the rest-stress protocol used for MPI in this study typically requires at least 4 hours to complete, whereas a CCTA study can be completed in <30 minutes. One important caveat to the primary differences found in this study was that a rest-stress protocol was used for all patients. Current radiation reduction recommendations suggest some of these patients could have undergone the more modern approach of stress first imaging, which would have dramatically reduced radiation exposures (typically by 75%), resulting in comparable radiation burdens for both modalities. This approach also reduces study times by several hours, which may have resulted in better patient experiences for MPI.
Keywords: Acute Coronary Syndrome, Adenosine, Angiography, Biomarkers, Catheterization, Chest Pain, Diagnostic Imaging, Electrocardiography, Myocardial Infarction, Myocardial Perfusion Imaging, Radiation Dosage, Telemetry, Tomography, Troponin T, Vasodilator Agents
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