Plaque Characteristic by Coronary CT Angiography Predict Abnormal Invasive Fractional Flow Reserve

Background:
Fractional Flow reserve (FFR) is considered the gold standard for detecting myocardial ischemia. We explored whether coronary CT angiography (CCTA) based plaque characteristics can predict an abnormal invasive FFR.

Methods:
Symptomatic patients undergoing both CCTA and invasive coronary angiography with FFR within 90 days of each other were included. CCTA images of the vessel evaluated with invasive FFR were analyzed for: lesion length (LL), lesion volume (LV), maximum plaque area (MPA), plaque burden (PB), plaque attenuation4 index (LL/MLD⁴). The associations of these parameters with abnormal FFR (<0.8) were examined.

Results:
Twenty seven vessels among 23 patients (age 58±11.8 years, 74% male) were included for analysis. Of the 27 vessels evaluated, 7 were abnormal by FFR. When compared with FFR negative lesions, FFR lesions positive for ischemia had smaller MLD (1.043±0.24 vs. 1.510±0.47mm, p=0.008), smaller MLA (1.09 ± 0.59 vs.2.49 ± 1.56 mm², p=0.011) and greater value of LL/MLD⁴ index (35.07 vs.10.91, p=0.022) and PB (80.86±12.61 vs.62.65±18.13%, p=0.031). For other plaque characteristics, no significant differences were found between ischemic lesion and non-ischemic lesions.

Conclusions:
Several non-invasive CCTA-based plaque characteristics (MLD, MLA, LL/MLD⁴ index and PB) were associated with abnormal invasive FFR. CCTA which allow a better appreciation of coronary plaques than conventional invasive angiography may be useful for assessing the hemodynamic significance of coronary plaques.