Abstract 17843: Comparison of IVUS Findings Using Different Tissue Characterization System; VH-IVUS vs. iMAP-IVUS in Patients with Acute Coronary Syndrome

Background: Two different tissue characterization techniques are available in the real world IUVS-guided percutaneous coronary intervention, VH-IVUS gave clinical implication especially identification of thin-cap fibroatheroma (TCFA) that can predict clinical event. The iMAP-IVUS system is relatively new technology available since last year in Korea. Limited data associated with iMAP-IVUS and no systemized report for comparison of two different systems. Methods: We performed pre-PCI IVUS using both VH-IVUS and iMAP-IVUS system consecutively for 20 patients with acute coronary syndrom treated with stent implantation. We excluded the 4 patients who had lesions with acoustic shadow on grey scale IVUS; because iMAP read the all shadows as necrotic core, then we selected and compared 30 pairs of cross-sectional tissue characterization IVUS images without acoustic shadow. Results: The VH-IVUS interpreted as less fibrotic (10.7 ± 7.9 vs 64.0 ± 5.9 %, p=0.001) when compared to iMAP-fibrotic components and much more fibro-fatty tissue components (64.4 ± 7.0 vs 9.0 ± 1.8 %, p =0.001) when compared to iMAP-lipid pool components for similar cross-sectional pairs. Necrotic core (22.7 ± 6.9 vs 26.9 ± 7.5 %, p =0.342) and calcified (2.1 ± 1.4 vs 6.8 ± 10.9 %, p =0.474) tissue components was similar between two systems. VH-IVUS detected 2 TCFAs but iMAP-IVUS could not fulfill the VH-definition of TCFA. Exact concordant level of cross-sectional IVUS image could not compared in few cases because VH-IVUS images were captured by EKG gating whereas iMAP IVUS by 2 frames/mm interval. Conclusion: Large necrotic core components were detected in two tissue characterization IVUS systems, but there were significant discrepancies in discriminations between fibrotic and lipid tissue components in patients with ACS who had lesions without acoustic shadow. We need more detailed study such as pathology study to verify the accuracy of these tissue characterization system.