Abstract 1730: Intraplaque Hemorrhage and Statin Therapy Alter the Natural History of Carotid Atherosclerosis: A Prospective Three Year Observational Magnetic Resonance Imaging Investigation
Purpose: Contrast enhanced magnetic resonance imaging (CE-MRI) has been validated with histology to accurately identify the lipid-rich necrotic core (LRNC), calcification (CA) and intra-plaque hemorrhage (IPH) in the carotid atherosclerotic lesion. The aim of this prospective, serial MRI study was to define the natural changes of the in vivo carotid plaque via high-resolution MRI in a population with moderate disease.
Methods: Twenty-two consecutive participants (95% males; mean age 59.9 yrs; 46% on statin therapy) with 50–79% stenosis by duplex ultrasound were enrolled in a prospective carotid disease observational study. CE-MRI was performed at 1.5T at baseline and 3 years. Two reviewers blinded to time point reached a consensus interpretation of each scan. Semi-automated image analysis tools were used to measure areas of the lumen (LA), wall (WA), CA, LRNC, fibrous tissue (FT) and IPH at each matched axial location. An ordinary bootstrap technique was applied to assess for mean (95% CI) arterial change in the identified metrics.
Results: Mean (SD) interval between scans was 2.9 (0.36) yrs. Table 1⇓ reports absolute mean (95% CI) annual change for each measurement of the entire population. LA decreased, whereas WA, LRNC and FT increased significantly. CA remained unchanged. In subjects without IPH during the observational period, statin users demonstrated no mean annual change in WA, while non-statin users progressed significantly at 3.5% per year (mean [95% CI] absolute change: 1.00 mm2/yr, 0.29 to 2.22). After controlling for statin use, the WA of participants with IPH had an increase in their mean (SE) annual progression rate of 1.31 (0.53) mm2/yr compared to subjects without IPH (p=0.02).
Conclusions: The carotid plaque appears to have a slow rate of change, which is reduced with statin therapy and advanced with IPH. These findings offer compelling evidence for the ability to non-invasively monitor temporal changes in the carotid lesion with MRI.