Abstract 1985: Increased Plaque Mass, but not Relative Plaque Composition, Distinguishes Culprit Coronary Artery Lesions in Patients with Acute Coronary Syndrome: A Lesion Analysis by Intravascular Ultrasound Histology
INTRODUCTION Intravascular ultrasound Virtual Histology (IVUS-VH) uses radiofrequency analysis to measure coronary artery plaque geometry and classify plaque components into one of four categories: fibrous, fibrofatty, necrotic or calcified. We hypothesized that patients with acute coronary artery syndrome (ACS) would have atherosclerotic plaque geometry and composition that differs from patients with stable, obstructive coronary artery disease.
METHODS In a crossectional study we used IVUS-VH to image 38 culprit lesions of 28 ACS patients and 104 lesions of 71 non-ACS patients prior to intervention. In both ACS and non-ACS patients, culprit lesions were defined as the site of percutaneous coronary intervention with at least 3 contiguous frames of > 40% percent plaque burden (100 × [external elastic membrane (EEM ) area − lumen area]/EEM area ) and a neointimal thickness > 600 um subtending an arc of > 10% vessel circumference. Plaque geometry and composition were measured with IVUS-VH software (pcVH v.2.2, Volcano Corp). A remodeling index was calculated as the ratio of the EEM area at the frame of the minimal lumen area to the EEM area of a reference frame (within 10 mm of MLA).
RESULTS Lesions of ACS patients were longer and had greater plaque volume than non-ACS patients (Table⇓). The proportions of IVUS-derived plaque components were similar in both ACS and non-ACS culprit lesions (Table⇓).
CONCLUSION Culprit coronary artery lesions in ACS patients have greater plaque mass than in non-ACS patients, but relative plaque composition is similar between these patient populations. Measurements of atherosclerotic plaque mass may discriminate better than plaque composition as to which patients with severe, obstructive coronary artery disease are at greatest risk of coronary artery thrombosis. Longitudinal studies using IVUS-VH will best resolve which IVUS-VH measurements of plaque geometry and composition have greatest predictive value.