Centralized Triage of Suspected Coronary Artery Disease Using Coronary Computed Tomographic Angiography to Optimize the Diagnostic Yield of Invasive Angiography

Background: Coronary computed tomographic angiography (CCTA) is preferable to invasive coronary angiography (ICA) for coronary artery disease (CAD) diagnosis in elective patients without known CAD. Methods: We conducted a nonrandomized interventional study involving 2 tertiary care centres in Ontario. From July 2018 to February 2020, outpatients referred for elective ICA were identified through a centralized triage process and were recommended to undergo CCTA first instead of ICA. Patients with borderline or obstructive CAD on CCTA were recommended to undergo subsequent ICA. Intervention acceptability, fidelity, and effectiveness were assessed. Results: A total of 226 patients were screened, with 186 confirmed to be eligible, of whom 166 had patient and physician approval to proceed with CCTA (89% acceptability). Among consenting patients, 156 (94%) underwent CCTA first; 43 (28%) had borderline/obstructive CAD on CCTA, and only 1 with normal/nonobstructive CAD on CCTA was referred for subsequent ICA against protocol (99% fidelity). Overall, 119 of 156 CCTA-first patients did not have ICA within the following 90 days (i.e., 76% potentially avoided ICA, due to the intervention). Among the 36 who underwent ICA post-CCTA per protocol, 24 had obstructive CAD (66.7% diagnostic yield). If all patients who were referred for and underwent ICA at either centre between July 2016 and February 2020 (n = 694 pre-implementation; n = 333 post-implementation) had had CCTA first, an additional 42 patients per 100 would have had an obstructive CAD finding on their ICA (95% confidence interval = 26-59). Conclusion: A centralized triage process, in which elective outpatients referred for ICA are instead referred for CCTA first, appears to be acceptable and effective in diagnosing obstructive CAD and improving efficiencies in our healthcare system.