Abstract 5092: Effects of Intensive Lipid Therapy on Atherosclerotic Plaque Burden and Time-course: A Prospective, Randomized, Double Blinded Study With Magnetic Resonance Imaging (MRI)
Background: Intensive lipid lowering therapy has been associated with regression of atherosclerotic disease burden. However, the time-course for response to therapy has not been established. In this study, we examined the effects of intensive lipid-lowering therapy on atherosclerosis burden and its time course over 3 yrs in the carotid artery.
Methods: Subjects (N=112) with coronary or carotid artery disease, apoB >= 120 mg/dl, received intensive lipid lowering therapy for 3 yrs. Subjects underwent carotid MRI scans at baseline and annually for 3 yrs. Expert reviewers, blinded to clinical information and scan time sequence, analyzed the atherosclerosis burden (percent wall volume (PWV) =100% × wall volume/[lumen volume + wall volume]). The burden change, expressed as ΔPWV, between pre- and post-therapy and the time course of changes over 3 yrs were compared. We also modeled (ΔPWV) as a function of the extent of maximum wall thickness (MaxWT) to assess association between the degree of disease in selected patients and ΔPWV.
Results: 84 subjects completed 3 yr follow-up scans with acceptable image quality. After 3 yrs of therapy, PWV significantly regressed (−3.8%, p<0.001). The time course over 3 yrs showed that PWV did not change significantly after the 1st yr (−0.3 %, p=0.7), but showed significant regression during the 2nd yr (−3.6 %, p<0.001). In this sample population, an additional year of therapy did not result in significant change from the reduction that occurred during the second year (+0.1 %, p=0.9). Average MaxWT at baseline was 2.27 mm (range: 1.0 to 5.6 mm). More thickened arteries showed significantly more reduction in atherosclerosis burden over 3 yrs compared to thinner arteries (p<0.001 for MWT slope, fitted linear regression model for ΔPWV: mean ΔPWV =0.46 – 0.41*MWT).
Conclusions: Maximal effect of intensive lipid-lowering therapy on atherosclerotic burden was observed after 2 years of therapy. This regression was mainly demonstrated in thickened arteries, but not in relatively normal (thinner) arteries. Our findings suggest that efficacy of lipid-lowering therapy on carotid plaque burden may be best evaluated in a population with pre-existing carotid atherosclerotic disease and 2 years of therapy.