Abstract 14014: Will Carotid Intima-Media Thickness Continue to Improve After Long-Term Lipid Therapy? A Carotid Ultrasound Study in the 20-Year Familial Atherosclerosis Treatment Study-Observational Study (FATS-OS)
Background: Carotid intima-media thickness (CIMT) has been established as surrogate marker for atherosclerosis and used to track treatment effect in populations that had not been treated intensively. Would CIMT still be reliable marker in prolonged intensively treated population?
Methods: We examined this question in 38 subjects with prolonged intensive lipid therapy in the 20-year FATS-OS. Carotid B-mode ultrasound was performed at the time of starting the triple therapy with Vytorin plus niacin and 2 years after. As previously reported that the triple therapy effectively lowers LDL-C to 68±32 mg/dl, triglycerides to 92±39, and non-HDL-C to 82±29, ApoB to 77±28, maintains HDL-C at 60±20 mg/dl and apoA1 at 154±37 in a group of subjects with untreated LDL-C at 200 mg/dl, triglycerides at 207 and HDL-C at 41 and have been intensively treated for near 20 years. All ultrasound scans of bilateral carotid arteries were performed using the SonoSite Micromaxx System. Both anterior and lateral view images were collected. CIMT measurements were performed using the SonoCal program. The CIMT of the 10mm adjacent segment distal to the carotid bulb of the far wall of the common carotid artery were measured from the most reprehensive images, blinded to the scan time points. CIMT of bilateral carotid arteries and both anterior and lateral views was compared between the 2 time points using paired t-test.
Results: Right CIMT at anterior view was 0.696±0.12 vs. 0.694±0.24 mm, p=0.8; lateral view was 0.727±0.17 vs. 0.731±0.16, p=0.9. Left CIMT at anterior view was 0.723±0.03 vs. 0.699±0.08 mm, p=0.6; lateral view was 0.776±0.01 vs. 0.786±0.14, p=0.7. The further statistical power analysis using the observed variation in this group showed that a minimum of 1239 subjects are required to be able to detect 0.01 mm difference over time and 2478 are required for 0.01 mm detectable difference between 2 treatment groups.
Conclusions: In subjects with prolonged intensive lipid therapy, CIMT did not change significantly over 2 years. Statistically, CIMT is no longer a sensitive marker for tracking atherosclerosis change in prolonged intensively treated population. These findings may help to explain the inconsistence results from the CIMT studies and have implication in future study design.
- © 2011 by American Heart Association, Inc.