Abstract 18072: Symmetrical Plaque Progression Rates in Bilateral Carotid Atherosclerosis: The Impact of Local Plaque Factors
Background: The development and progression of atherosclerosis is governed by systemic and local factors. Carotid magnetic resonance imaging (MRI) allows volumetric measurement of plaque burden and composition, and is emerging as an effective tool for monitoring plaque progression. The purpose of this study was to evaluate the symmetry of progression or regression of bilateral carotid atherosclerosis during a seven month follow-up period.
Methods: As the placebo arm of a multi-center clinical trial, 54 subjects with 16-79% carotid stenosis by ultrasound and presence of a lipid core on baseline MRI underwent follow-up carotid MRI at seven months. Wall, lipid core, and plaque components such as intraplaque hemorrhage (IPH) and ulcer were assessed on both sides on the baseline and follow-up scans. Readers were blinded to demographic and clinical risk factor data, as well as the time sequence of the scans. Progression between bilateral carotid plaques was calculated as changes within the common coverage between scans.
Results: Forty-three (79.6%) of the subjects were on lipid-lowering therapy. Mean low-density lipoprotein cholesterol decreased from 86.1 ± 26.8 to 76.5 ± 24.8 mg/dL during the course of the study (p = 0.002). Bilateral wall volume progression or regression was found in 31 subjects (57.4%) and unilateral IPH was present in six (11.1%) subjects at baseline. In the sample as a whole, there was little correlation in wall volume progression between sides (r=-0.02, p=0.883). However, progression was significantly correlated between sides in the group without IPH (r=0.31, p=0.034) and was significantly different (p=0.011) than in the group with unilateral IPH (r=-0.60, p=0.208). In those with IPH, mean progression was 29.9 ± 55.7 mm3 on the side with IPH and -26.9 ± 29.3 mm3 on the non-IPH side (p=0.131).
Conclusions: In the absence of intraplaque hemorrhage, carotid atherosclerotic lesion volume tends to change in the same direction bilaterally, potentially due to systemic processes. The presence of intraplaque hemorrhage disrupts this association. Our findings suggest that this local factor can override systemic factors, and should be accounted for in the design of clinical trials intended to assess the effect of novel therapy on plaque regression.
- © 2012 by American Heart Association, Inc.