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CT Angiography to Guide Management of Coronary Disease
Study Questions:
What is the impact of coronary computed tomography (CCTA) on utilization of invasive coronary angiography, institution of preventive medication, and clinical outcomes?
Methods:
Data were derived from the SCOT-HEART (Scottish Computed Tomography of the Heart Trial) study, in which 4,146 patients seen in a chest pain clinic for suspected angina were randomized to standard care or standard care plus CCTA. Standard care included cardiovascular stress testing. CCTA included coronary artery calcium scoring and assessment of coronary anatomy as normal (<10% cross-sectional stenosis), nonobstructive (mild 10-49%, moderate 50-70%), or obstructive (>70%) coronary artery disease. The national electronic health record was utilized to obtain information on medical resource utilization.
Results:
Average age was 57 ± 10 years and 56% of subjects were male. Patients were followed for 3-49 months (median 20). Of those randomized to CCTA, 1,778 (86%) had the study accomplished. CCTA revealed normal coronary arteries in 654 (37%), mild nonobstructive disease in 372 (21%), intermediate nonobstructive in 300 (17%), and obstructive in 452 (25%) of study subjects. At 6 weeks, CCTA was associated with a higher rate of referral for standard coronary arteriography (94 vs. 8; odds ratio [OR], 12.85; p < 0.0001). Over the total trial period, the number of standard coronary arteriograms performed did not differ between the CCTA and standard of care groups (409 vs. 401; hazard ratio [HR], 1.06; p = 0.451). Standard coronary arteriography demonstrated normal coronary arteries in 20 patients in the CCTA group versus 56 in the standard of care group (HR, 0.39; p < 0.001) and was more likely to show obstructive disease (283 vs. 30; HR, 1.29; p = 0.005) in the CCTA cohort. Compared to standard care, more patients were recommended initiation of cardiac-specific medical therapy in the CCTA group (293 vs. 84; OR, 4.12; p < 0.001). Rates of fatal and nonfatal myocardial infarction were lower in the CCTA cohort (26 vs. 42; HR, 0.62; p = 0.527). When considering events occurring ≥50 days after initial clinic visit, the rate of fatal versus nonfatal myocardial infarction was 17 versus 34 in the CCTA versus standard of care group (HR, 0.50; p = 0.00202). Over 6 months, the cumulative mean cost of treatment in the CCTA group was $1,900 versus $1,438 in the standard of care group.
Conclusions:
A strategy of early CCTA leads to more appropriate use of invasive angiography, modification of preventive medical therapy, and a reduction in fatal and nonfatal myocardial infarction compared to standard care.
Perspective:
The results of this study confirm a role for CCTA in the early initial evaluation of patients presenting with angina and suspected coronary artery disease. Because of the nature of the medical care system where this study was done, not all results will translate to care in the United States or other medical environments. A major conclusion from this study is that early CCTA results in a more appropriate utilization of invasive coronary arteriography and a more aggressive approach to medical management of patients with angina, presumably because of demonstration of a significant atherosclerotic burden on CCTA. The greater utilization of medical therapy in the CCTA cohort resulted in a decrease in events. As anticipated, the cost of the CCTA strategy exceeded that of the standard of care; however, the absolute dollar values reported in this manuscript will bear little relationship to cost of care in the healthcare system in the United States.
Keywords: Ambulatory Care, Angina Pectoris, Angiography, Chest Pain, Constriction, Pathologic, Coronary Angiography, Coronary Artery Disease, Diagnostic Imaging, Electronic Health Records, Myocardial Infarction, Primary Prevention, Standard of Care, Tomography
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