Comparison between minimum lumen cross-sectional area and intraluminal ultrasonic intensity analysis using integrated backscatter intravascular ultrasound for prediction of functionally significant coronary artery stenosis.

Intravascular ultrasound (IVUS)-derived minimum lumen cross-sectional area (MLA) is useful to predict myocardial ischemia using fractional flow reserve (FFR). Recent studies reported an increase in the intraluminal ultrasonic integrated backscatter (IB) value using IVUS across the coronary artery stenosis (CAS) was significantly correlated with FFR. However, these details have not been fully understood. We evaluated the utility of intraluminal IB analysis for predicting myocardial ischemia based on FFR measurements by comparing that with conventional IVUS-derived MLA. A total of 65 patients with 75 intermediate lesions underwent both FFR and IB-IVUS simultaneously were analyzed. We measured IVUS-derived MLA and intraluminal IB value at the coronary ostial site, 5 mm distal site to the CAS, and far distal site, which is the same as the position of the pressure wire sensor. The increase in IB values was calculated as the distal IB value - the ostial IB value (focal ∆IB) and the far distal IB value - the ostial IB value (total ∆IB). MLA did not show a significant correlation with FFR (p = 0.13); however, focal ∆IB and total ∆IB showed significant correlations with FFR (p = 0.008 and p < 0.001, respectively). The receiver operating characteristic curve analysis shows that the best cut-off value of focal ∆IB and total ∆IB was 8 and 14, respectively. Although the diagnostic abilities to predict FFR ≤ 0.75 among IVUS-derived MLA ≤ 3.0 mm2, focal ∆IB ≥ 8, and total ∆IB ≥ 14 were similar, a multivariate analysis showed that total ∆IB was the most useful index (p < 0.001). In conclusion, total ∆IB, which is measured at the same as the position of FFR measurement, might be useful for functional assessment of intermediate CAS.