Abstract 18548: Validation of a New Imaging Parameter, Ultrasonic Intensity of Blood Speckles, Measured by Intravascular Ultrasound for Assessment of Coronary Stenosis Severity Comparing with Fractional Flow Reserve

Abstract

Background : Little is known regarding intravascular ultrasound (IVUS) criteria to determine functional severity of coronary stenosis. Ultrasonic intensity of blood speckles (IBS) increases as blood flow decreases below coronary stenosis in clinical observation of gray-scale IVUS. The present study was conducted to determine IVUS parameters indicating functional significance of intermediate coronary stenotic lesions. Methods and Results : Thirty consecutive patients with angiographically single intermediate stenotic lesion in left anterior descending coronary artery were enrolled in this study. They were evaluated by means of IVUS and intracoronary pressure measurements. In IVUS analysis conventional gray-scale images were recorded and averaged integrated backscatter (IB) values of blood speckles were measured in cross-sectional vessel lumens at left main trunk (proximal) and 5 mm distal of targeted lesion (distal) using Terumo radiofrequency IVUS (RF-IVUS) system. IBS was defined as difference of IB values between the proximal and the distal sites (distal IB - proximal IB). Fractional flow reserve (FFR) was measured at maximal hyperemia induced by intravenous adenosine infusion. FFR < 0.80 at maximum hyperemia was seen in 19 (63%) of total 30 lesions. IBS had significantly negative correlation with FFR (r = - 0.57, p = 0.001). The optimal cutoff value of IBS for FFR < 0.80 was 10.0 which was obtained from receiver operating characteristic curve (area under curve 0.88; p = 0.001) (Figure). Sensitivity and specificity at the cutoff were 85 % and 70 %, respectively. Also, IBS wasan independent determinant of FFR (H.R. 1.23; 95% confidence interval [CI], 0.008 to 0.031; p = 0.008) in multivariate analysis. Conclusion : IBS, a brand-new IVUS parameter, obtained by RF-IVUS analysis showed a significant correlation to FFR values and can be a predictor for functional significance of epicardial coronary stenosis.