Objective: Common carotid artery (CCA) intima-media thickness (IMT), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C), but not triglyceride levels, are markers of future cardiovascular events. The relationship between these three factors is, however, unclear.
Methods: We included six large observational studies that used the same harmonized, B-mode ultrasound protocol, the same software for IMT measurement by automatic edge detection on CCA in a plaque-free region, following the Mannheim consensus, and certification of all sonographers. Using the best view of the CCA, the sonographer had to confirm that the quality index was ≥ 0.5 on a measurement performed on 10-mm length. We used individual data meta-analysis to estimate the cross-sectional associations of lipids with CCA-IMT.
Results: Overall, 21,587 patients with complete information on lipids and CCA-IMT were available. Age- and sex-adjusted CCA-IMT differed by -7.8 μm (95% CI -9.1 to -6.5 μm, P < 0.001) per 1 SD higher HDL-C level. After further adjustment for other atherosclerosis risk factors, the relationship was attenuated, but remained significant (regression coefficient, -3.7 μm; P < 0.001). This was found regardless of LDL-C levels (P for heterogeneity = 0.70). After adjustment for age and sex, triglycerides were positively associated with CCA-IMT, overall and in each LDL-C subgroup, but not after further adjustments for other risk factors.
Conclusions: Relationships between HDL-C and triglyceride levels and CCA-IMT were consistent with that previously observed with clinical events by the Emergency Risk Collaboration group, including at low LDL-C levels. This reinforces the need to verify whether raising HDL-C levels decreases both CCA-IMT and future clinical events.
Keywords: Carotid arteries; Lipids; Meta-analysis.
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