Fluid dynamics informed CCTA-derived geometric parameters in right coronary artery anomalies predict abnormal invasive Adenosine FFR and Dobutamine FFR

Abstract

Background: Right anomalous aortic origin of coronary arteries (R-AAOCA) involves fixed compression, assessable with adenosine-derived fractional flow reserve (FFRAdnosine), and additional stress-induced dynamic compression captured by dobutamine-derived FFR (FFRDobutamine). We hypothesized that coronary CT angiography (CCTA)-derived fluid dynamics-informed parameters outperform conventional metrics in predicting both FFR types. Methods: We retrospectively analyzed CCTA data from R-AAOCA patients who underwent invasive FFRAdnosine and FFRDobutamine assessment. Parameters were categorized as: (1) conventional metrics (cross-sectional area, perimeter, minor/major axis, intramural lumen area [ILA], effective diameter, area and diameter stenosis ratios) and (2) fluid dynamics-informed metrics (hydraulic diameter, elliptic ratio, circularity, hydraulic diameter stenosis ratio, resistance index [RI], ostial angulation penalty [OAP], and comprehensive stenosis score [CSS]). Hemodynamic relevance was defined as FFR$\leq$0.80. Results: 81 patients were included. FFRAdnosine$\leq$0.80 occurred in 5 (6.2%) and FFRDobutamine$\leq$0.80 in 16 (19.8%) patients. For FFRAdnosine, top discriminators were RI (AUC=0.97), OAP (AUC=0.97), ostial area (AUC=0.96), and CSS (AUC=0.95). For FFRDobutamine, ostial minor diameter led (AUC=0.85), followed by RI (AUC=0.83) and ILA minor diameter (AUC=0.81). RI explained 45% and 43% of FFRAdnosine and FFRDobutamine variance, respectively. At optimal thresholds, RI achieved 100% sensitivity and 95% specificity for FFRAdnosine; ostial minor diameter achieved 100% sensitivity and 57% specificity for FFRDobutamine. Conclusions: In R-AAOCA, CCTA-derived fluid dynamics-informed metrics provide excellent and superior performance compared with conventional geometric parameters in predicting hemodynamic relevance of fixed compression.