Abstract 1980: Coronary Artery Plaque Mass Increases but Relative Plaque Composition Remains Constant in Patients with Greater Framingham Estimate of Cardiac Risk: An Analysis by Intravascular Ultrasound Virtual Histology
BACKGROUND Intravascular ultrasound Virtual Histology (IVUS-VH) measures coronary artery plaque geometry and classifies plaque components into one of four categories: fibrous, fibrofatty, necrotic or calcified. It is not well established whether imaging by IVUS-VH identifies coronary arteries vulnerable to thrombosis and, thus, a patient at higher risk for myocardial infarction or sudden death. In lieu of longitudinal studies that employ IVUS-VH, we compared whole vessel IVUS-VH measurements of plaque burden and plaque composition to Framingham estimates of 10-year cardiac risk.
METHODS We performed an interim analysis of IVUS-VH measurements from one vessel per patient enrolled in the multicenter IVUS-VH Global Registry. Each patient was stratified into one of three groups based on a Framingham 10-year cardiac risk of < 10%, 10 to 20%, or > 20%. Patients were excluded from analysis if angioplasty preceded IVUS-VH imaging or if missing data precluded calculation of Framingham risk.
RESULTS The final study population consisted of 565 patients. Vessel (external elastic membrane) area, plaque + media area (vessel area − lumen area) and percent plaque burden (100 × plaque + media area/vessel area) significantly increased with increased Framingham estimate of cardiac risk. The proportion of each plaque component defined by IVUS-VH was similar across categories of Framingham cardiac risk.
CONCLUSION Whole vessel analysis by IVUS-VH revealed that an increase in coronary artery plaque mass was associated with greater estimated cardiac risk. However, no significant relationship existed between relative plaque composition and estimated cardiac risk. Longitudinal studies will best resolve whether IVUS-VH-derived measurements of coronary artery plaque geometry and composition have predictive value.