Relation between functional stenosis and tissue characterization of intermediate coronary plaques in patients with stable coronary heart disease

Background: Tissue characteristics of coronary plaques can be evaluated using integrated backscatter intravascular ultrasound (IB-IVUS), while fractional flow reserve (FFRmyo) is an index of functional coronary stenosis. We assessed the relation between functional stenosis and the characteristics of plaque tissue using FFRmyo and IB-IVUS.

Methods and results: A total of 17 lesions with 75%-stenosis assessed visually by coronary angiography from 17 stable angina patients (64.2+/-9.1 years old, 11 males) were studied. IB-IVUS was evaluated in the most stenotic cross-sectional area. Using commercially available software, coronary plaques were assessed for calcification (CA), fibrosis (F), and lipid pool (LP). Lesions were localized in the left anterior descending artery in 11 patients, the left circumflex in 3, and the right coronary artery in 3. On quantitative coronary angiography, the percent diameter stenosis (%DS) was 60.5+/-7.3%. Plaque burden was 71.4+/-9.1%, FFRmyo was 0.74+/-0.13. The tissue component of the plaques was: CA(%), 3.0+/-2.4%; F(%), 60.5+/-9.6%; LP(%), 37.2+/-11.0%. Significant correlation was not observed between %DS or plaque burden and FFRmyo, structural stenosis and plaque characterization, nor between CA(%) and FFRmyo. There was a positive correlation between F(%) and FFRmyo (r=0.62, p<0.01) and a negative correlation between LP(%) and FFRmyo (r=-0.52, p<0.05).

Conclusion: Our findings indicate that the tissue characteristics of coronary plaques in intermediate lesion affect functional stenosis.