Abstract 9917: The Site of Greatest Vulnerability is Most Often Located Proximally to the Site of Most Severe Narrowing: A Virtual Histology Intravascular Ultrasound Study

Abstract

Introduction: Previous angiographic studies have shown that almost two-thirds of vulnerable plaques are located in non-obstructive lesions. However, the spatial relationship between the location of most severe narrowing and vulnerable rupture sites has not been fully elucidated. Probably, the site of greatest vulnerability is not always identical to the site of most severe stenosis. Therefore, the aim of the present study was to assess the spatial relationship between the location of the site of greatest vulnerability and the location of most severe narrowing with VH IVUS. Methods: Overall, 77 patients (139 vessels) underwent VH IVUS. The site of greatest vulnerability was defined as the cross-section with the largest necrotic core area per vessel, the maximum necrotic core (Max NC) site. The site of most severe narrowing was defined as the minimum lumen area (MLA). Per vessel the distance from both the Max NC site and MLA site to the origo of the coronary artery was evaluated. In addition, the presence of a thin cap fibroatheroma (TCFA) was assessed. Results: The mean difference (mm) between the MLA site and Max NC site was 10.8±20.6mm (P<0.001). Interestingly, the Max NC site was located at the MLA site in 7 vessels (5%) and proximally to the MLA site in 92 vessels (66%). Besides, a higher % of TCFA was demonstrated at the Max NC site as compared to the MLA site (24% versus 9%, P<0.001). Conclusion: The present findings demonstrate that the site of greatest vulnerability is rarely at the site of most severe narrowing. Most often, the site of greatest vulnerability is located proximally to the site of most severe narrowing. Furthermore a higher percentage of TCFA (plaque phenotype with high-risk of rupture) was demonstrated at the site of greatest vulnerability. Figure 1 Difference in distance (mm) and distribution between Max NC site and MLA site. In the majority of vessels the site of Max NC is located proximal to site of MLA.