Performance of functional and morphological evaluations of intermediate coronary lesions during long-term follow-up

Abstract Introduction Coronary CT angiography (CCTA) has become one of the main imaging modalities for stable coronary artery disease (CAD) 1. The evaluation of atherosclerotic plaque can now be improved through detailed coronary artery plaque (CAP) analysis using dedicated CCTA software. Quantitative flow ratio (QFR) is a novel, angiography (ICA) based technique that allows for the evaluation of the functional significance of coronary artery stenosis 2. Purpose The aim of this study was to compare detailed CAP features with QFR based functional analysis of the same lesion, with a long-term perspective on lesion revascularization (PCI). Methods A total of 45 patients with no previous history of CAD were enrolled in this study. All patients underwent CCTA and were diagnosed with intermediate stenosis (IS) (defined as 50-69%), followed by ICA and QFR analysis. For CAP analysis in IS, a semi-automated, dedicated CCTA program (QAngio CT) was used. For the same IS lesion post-ICA QFR analysis was performed (QAngio XA-3D QFR analysis solution version 2.0). 7-year follow-up (FU) was conducted to evaluate the prognostic value of significant CAP features for IS PCI. QFR analysis was performed after the decision to proceed with IS PCI had been made (median time to PCI: 2178.0±747.40). Results We studied 45 lesions and categorized them as non-significant (QFR-negative, QFR≥0.80; n=29) and functionally significant (QFR-positive, QFR0.80, n=16) based on QFR values. CAP morphologic parameters (44 evaluated) did not differ significantly between the QFR groups. However, correlation analysis revealed a moderate positive correlation between QFR values and both lumen area (mm2) and mean lumen diameter (mm) at the site of maximal obstruction (Table 1). More than one-third of FU patients underwent IS PCI (37.8%). In whole-lesion analysis, lower lumen volume (mm3) and greater minimal plaque thickness (mm) were significantly associated with IS PCI. Additionally, analysis at the site of maximal obstruction showed that smaller lumen area, mean lumen diameter, and minimal diameter were significantly associated with PCI (Table 2). Significant predictors of PCI included lumen volume, lumen area, and mean lumen diameter (Table 3). Furthermore, the frequency of PCI was significantly higher in the QFR-positive group (Table 4) and QFR values were significantly lower in the PCI group compared to the no-PCI group (0.78 0.076 vs. 0.90 0.100, p0.001). Conclusion Our study demonstrated a moderate correlation between QFR and anatomical vessel parameters, suggesting that the functional severity of stenosis is associated with the anatomical narrowing. Over a 6-year FU period, both morphological and functional parameters emerged as significant predictors of IS PCI. These findings underscore the importance of integrating both types of measurements in clinical decision-making. Future studies with larger cohorts are warranted to validate these results.