Abstract 19162: Impaired Segmental Coronary Artery Distensibility is Associated with Vulnerable Plaque Composition Measured by Virtual Histology Intravascular Ultrasound
Background: Vascular dysfunction and atherosclerosis are systemic disorders, but are often characterized by segmental involvement and complications. We recently reported that impaired coronary distensibility index (CDI), a marker of vascular function, is associated with the severity of coronary artery disease (CAD). This study investigates the association between the composition of coronary atherosclerotic plaque and CDI within coronary artery segments using virtual histology intravascular ultrasound (VH-IVUS).
Methods: One hundred and forty coronary artery segments of 54 symptomatic subjects without obstructive CAD (luminal stenosis <50%, age 59±6 and 100% male) who underwent invasive angiography and VH-IVUS, were analyzed. The four VH-IVUS plaque components [dense calcium (DC), necrotic core (NC), fibrous (FI) tissue, and fibro fatty (FF)] were analyzed in each segment. Segmental CDI was defined as: [(early-diastole CSA — end-diastole CSA)/ (lumen CSA in end-diastole x central pulse pressure) x 103]. Coronary wall thickness (CWT) was measured at mid-diastole. CDI below median was defined as an impaired CDI.
Results: There was excellent inverse correlation between CDI and CWT (r= −0.83, p=0.0001). CDI decreased proportionally form normal segments (5.91±0.42) to diseased segments (3.54±0.41) (P<0.001). The relative portion of NC (32% vs. 11%) and FF (23% vs. 13%) was higher in segments with impaired CDI as compared to normal CDI. (Figure) After adjustment for cardiovascular risk factors, the relative risk for each standard deviation decrease in CDI was 2.2 (95%CI 1.5–2.8, p=0.0001) for NC and 1.6 (95%CI 1.2–2.1, p=0.001) for FF as compared to normal segments.
Conclusions: This study documents that impaired segmental coronary distensibility is associated with plaque characteristics that are typical of vulnerable plaques in subjects without obstructive CAD.
- Vulnerable plaque
- Endothelial function
- Intravascular ultrasound/Doppler
- Coronary artery disease
- © 2010 by American Heart Association, Inc.