P3648Prevalence of thin-cap fibroatheroma in relation to the physiological stenosis severity determined by fractional flow reserve and instantaneous wave-free ratio

Abstract

Background: The relationship between the features of morphologically unstable plaque and physiological lesion severity remains elusive. Invasive physiologic indices, such as fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR), are used in clinical practice and no comparisons have been reported between the coronary flow characteristics derived from concordance or discordance of FFR/iFR and optical coherence tomography (OCT)-derived high-risk plaque features. Method(s): We investigated 259 de novo intermediate and severe coronary lesions in 259 patients who underwent OCT and FFR, IFR examinations. Patients were eligible for the analysis if lesions with stable angina pectoris or acute coronary syndrome with non-culprit lesion observations. Established cutoff values of pressure-derived physiologic indices (FFR <0.89) were used to dichotomize stenoses into concordantly classified (FFR+/iFR+ and FFR-/iFR-) and discordantly classified (FFR+/iFR- and FFR-/iFR-) groups. OCT-derived plaque characteristics were compared across 4 vessel groups; FFR+/iFR+ (153 vessels, 59.1%), FFR-/iFR+ (16 vessels, 6.2%), FFR+/iFR- (60 vessels, 23.2%), FFR-/iFR- (30 vessels, 11.6%). OCT analysis included the presence or absence of plaque rupture, thin-cap fibroatheroma (TCFA), lipid-laden neointima, calcification, intraluminal thrombus, macrophage accumulation. Result(s): FFR-based decision making disagreed with that of iFR in 29.3% (76 vessels). TCFA was found in 15.4% (40 vessels). Frequency of plaque rupture, thrombus, macrophage accumulation, and calcification was not significantly different among 4 vessel groups. However, prevalence of TCFA was significantly different among 4 vessel groups (P=0.036); FFR+/iFR+ (n=32, 20.9%), FFR-/iFR+ (n=1, 6.2%), FFR+/iFR- (n=4, 6.7%), FFR-/iFR- (n=3, 10.0%). On univariable logistic regression analysis, both FFR and iFR were significantly associated with the presence of TCFA. [FFR: HR 0.002, 95% CI 3.87x10-5-0.06, P<0.001, iFR: HR 0.102, 95% CI 0.014-0.754, P=0.025] In FFR+/iFR+ concordant group, the prevalence of TCFA was significantly greater than the other 3 vessel groups combined (32/153 vs 8/106, P=0.005). Conclusion(s): Physiological severity of coronary stenosis evaluated by FFR and iFR was associated with plaque instability regarding the presence of TCFA. Lesions with positive FFR and iFR concordance may identify high probability of the presence of TCFA.