Appropriate Use Criteria for Cardiac Computed Tomography: Does Computed Tomography Have Incremental Value in All Appropriate Use Criteria Categories?

Purpose: Cardiac imaging expenditures have come under scrutiny, and a focus on appropriate use criteria (AUC) has arisen to ensure cost-effective resource utilization. Although AUC has been developed by clinical experts, it has not undergone rigorous quality assurance testing to ensure that inappropriate indications for testing yield little clinical benefit. The objective of the study was to evaluate the potential incremental prognostic value of coronary computed tomographic angiography (CCTA) in the different AUC categories. Materials and Methods: Consecutive patients enrolled into a cardiac CT Registry were collated. Patient indications were reviewed and based on the 2010 AUC (appropriate, uncertain, and inappropriate). Patients were followed-up for death, myocardial infarction (MI), and late revascularization, with the primary composite endpoint being cardiac death, nonfatal MI, and late revascularization. The prognostic value of CCTA over clinical variables in each of the AUC categories was assessed. Results: Indications for CCTA were appropriate, uncertain, and inappropriate in 1284 (66.5%), 312 (16.2%), and 334 (17.3%) patients, respectively. Rates of all-cause of death, cardiac death, nonfatal MI, and late revascularization were similar across patients with appropriate, uncertain, and inappropriate indications for CCTA. Moreover, in each AUC category, CCTA had incremental prognostic value over a routine clinical risk score (National Cholesterol Education Program) with hazard ratios of 9.98, 7.39, and 5.61. Conclusions: CCTA has incremental prognostic value in all AUC categories, even when the reason for the study was deemed "inappropriate." This suggests that CCTA may still have clinical value in "inappropriate" indications and that further quality assurance AUC studies are needed.