The triple line pattern on carotid intima media thickness imaging and its relationship to cardiovascular risk factors in patients on lipid lowering therapy

BACKGROUND Carotid intima media thickness (CIMT) infrequently identifies a triple line pattern (TLP) in the visualization of the internal elastic lamina. We examined the prevalence and predictors of the TLP among a consecutive series of subjects enrolled in a CIMT clinical trial, and also the effects of lipid lowering therapy. METHODS Baseline CIMT studies of subjects with known heart disease, or high risk for heart disease, were evaluated from a single site of the Arterial Biology for the Investigation of the Treatment Effects of Reducing Cholesterol 6-HDL and LDL Treatment Strategies in Atherosclerosis trial (N=120). One sonographer obtained four views of the right and left far wall common CIMT, using a 13 MHz ultrasound probe. Images were blindly reviewed for the presence of the TLP. The TLP was defined as absent (0), possible (1), or definite (2). A composite score from all four views was calculated. A patient was defined as having the TLP if the composite score was ≥4. Univariate predictors of the TLP were explored. Follow-up ultrasounds at 14 months were also reviewed for presence of the TLP. RESULTS The prevalence of the TLP at baseline was 22.5%. Among cardiovascular risk variables, systolic blood pressure was significantly higher in subjects displaying the TLP (141.3±15.6 mmHg versus 133.1±18.4 mmHg; P=0.036). There were no differences among those with, and without, the TLP, with respect to other cardiovascular risk variables (age, sex, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, C-reactive protein, glucose, weight, waist girth, tobacco use, medications, quantitative CIMT), or image quality. During ongoing lipid lowering therapy, the prevalence of the TLP increased to 54.2% (P<0.001). However, it was unrelated to changes in lipid concentrations or cardiovascular risk variables. CONCLUSION The TLP in CIMT imaging is commonly identifiable using high-frequency ultrasound, and appears to be associated with higher systolic blood pressure. Its prevalence and incidence is unrelated to lipid parameters.