Adults with anomalous aortic origin of a coronary artery: Impact of invasive functional testing on clinical decision making – insights from the MuSCAT registry

Background In line with the contemporary ESC and AHA/ACC guidelines, the work-up for anomalous aortic origin of a coronary artery (AAOCA) should include anatomical and functional evaluation. Objective This study aims to evaluate the impact of invasive functional testing versus real-world non-invasive functional testing on the management strategy for adults with potentially malignant AAOCA. Methods In this multicenter prospective study, all AAOCA patients, ≥16 years, with an interarterial or intraseptal course underwent diagnostic work-up, including anatomic and non-invasive functional evaluation. Invasive functional testing followed the MuSCAT protocol with fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR)/resting full-cycle ratio (RFR), and intravascular ultrasound (IVUS) at baseline and during pharmacological stress. Results Seventy-six patients (53% female, median age 53 [44-59] years) were included. Sixteen (21%) initially presented with cardiac chest pain. High-risk anatomy, e.g. acute take-off angle <30°, was present in 75 (99%) patients. Non-invasive functional testing was positive in 10 (13%), negative in 59 (78%) and inconclusive in 2 (3%). Invasive functional testing showed discrepant results compared to non-invasive testing in 21 (28%) patients. In 15 (20% of the overall cohort) patients the treatment recommendation was altered based on the invasive functional testing results. Conclusions This study in adult AAOCA patients revealed a 28% discrepancy between non-invasive and invasive functional testing, altering management recommendations for 20% of the overall cohort. Implementing optimal functional testing modalities may enhance risk stratification for ischemic events and sudden cardiac death, enabling tailored treatment strategies for AAOCA patients. Further prospective research with long-term follow-up is needed to evaluate clinical outcomes. Registered in the Dutch Trial Register #NL8777; https://onderzoekmetmensen.nl/en