Correlation between frequency-domain optical coherence tomography parameters and fractional flow reserve in angiographically intermediate coronary lesions: A prospective observational study

Background: Intermediate coronary lesions (ICLs) are challenging to assess using angiography alone. While fractional flow reserve (FFR) is the physiological gold standard, frequency-domain optical coherence tomography (FD-OCT) provides detailed anatomical insights. The relationship between FD-OCT metrics and FFR-defined ischemia remains unclear. Aim: This study aims to evaluate the correlation between FD-OCT-derived anatomical parameters and FFR in patients with ICLs, and to identify morphological features predictive of physiological significance. Materials and Methods: In this prospective, single-center observational study, 58 patients with angiographically defined ICLs (50%–80% diameter stenosis) underwent both FD-OCT imaging and FFR assessment. OCT parameters – including Minimum lumen area (MLA), Minimum lumen diameter (MLD), percentage area stenosis (AS), and plaque morphology – were compared between lesions with FFR ≤0.80 and >0.80. Correlations with anthropometric variables were also examined. Results: Of the 58 lesions, 23 (39.7%) were physiologically significant (FFR ≤ 0.80). These lesions showed significantly lower MLA (1.84 ± 0.36 mm 2 vs. 2.31 ± 0.26 mm 2 ), lower MLD (1.24 ± 0.13 mm vs. 1.54 ± 0.17 mm), and higher AS (64.56% ±5.59% vs. 51.72% ±5.67%) compared to FFR-negative lesions (all P < 0.05). Fibroatheromatous and calcified plaques with arc >180° were more prevalent in FFR-positive lesions. MLA showed significant positive correlations with height, weight, waist, and wrist circumference (P < 0.05), but not with body mass index. Conclusion: FD-OCT-derived MLA and AS strongly correlate with FFR and can serve as reliable anatomical indicators of lesion significance. Morphological features further enhance risk assessment, supporting the combined use of OCT and FFR for evaluating ICLs.