Abstract 428: Progression Patterns of Carotid Atherosclerotic Plaques with and Without Intraplaque Hemorrhage Monitored for 6 Months: A Multicenter Magnetic Resonance Imaging Study

Background: Carotid magnetic resonance imaging (MRI) is emerging as an effective tool for monitoring plaque progression noninvasively. However, data from multi-center studies are scarce. Intraplaque hemorrhage (IPH) has been shown to promote plaque growth. In this multi-center study over 6 months, we sought to study plaque progression in subjects with and without IPH. Methods: As the placebo arm of a multi-center clinical trial, 59 subjects with 16-79% carotid stenosis by ultrasound and a lipid core (LC) on baseline MRI completed a follow-up MRI at the end of a 6-month period. Thirty-nine (66.1%) were on concurrent rosuvastatin therapy. Lumen, wall and LC volumes, and IPH presence were measured on both scans blinded to time sequence at a core lab. Plaque progression was calculated as annualized changes within the common coverage between scans using the carotid bifurcation as a landmark. Results: IPH was present on 14 slices from 3 (5.1%) subjects at baseline. Subjects without IPH (n=56) showed a significant reduction in LC volume (p=0.031), a trend towards reduction in wall volume (p=0.215) and no apparent change in lumen volume (p=0.910). Although all subjects with IPH were on rosuvastatin during the study period, compared to subjects without IPH, they had increased LC (62.9±46.2 mm3/year vs. -8.8±29.9 mm3/year, p<0.001) and wall (100.1±78.1 mm3/year vs. -12.7±75.8 mm3/year, p=0.015) volumes, but decreased lumen volume (-93.4±114.7 mm3/year vs. 0.90±59.7 mm3/year, p=0.014). Conclusion: This multi-center study over 6 months demonstrated significant regression in LC volume in plaques without IPH. By contrast, plaques with IPH may be poorly controlled despite statin therapy.