Association of elevated lipoprotein(a) levels with impaired arterial elasticity and endothelial glycocaclyx

Background Lipoprotein (a) is liver-generated lipoprotein which consists of LDL-particles attached apolipoprotein (a). Increased Lp(a) levels are implicated in the clinical course of atherosclerosis. Purpose We investigated whether participants with increased Lp(a) levels demonstrate altered arterial wall stiffness and thickness of endothelial glycocalyx. Methods we included participants from the primary prevention clinic of the Cardiology Department of our University Hospital. We performed propensity score matching for age, sex, diabetes, hypertension and smoking. We totally enrolled 90 participants of which a) n=30 participants had elevated Lp(a) levels as defined by Lp(a) >50mg/dl with the rest lipids within near optimal range b) n=30 participants with increased Total Cholesterol and non-HDL levels with normal Lp(a) and c) n=30 participants with lipid levels within reference range as controls. We measured at enrollment a) perfused boundary region (PBR) of the sublingual microvessels with a lumen diameter ranging from 4 to 25 μm, as a marker of endothelial glycocalyx integrity and b) carotid-femoral pulse wave velocity, Pulse Pressure (PP) and central systolic blood pressure (cSBP) as markers of arterial stiffness. Results We included participants aged 54±9 years, 43/90 (47.7%) were males. Participants with increased lipid levels had higher total cholesterol and non-HDL levels compared to Lp (a) and control group (p<0.05). The Lp (a) and the hyperlipidemia group showed similar PBR values and both groups higher than the control group (PBR 4-25: 2.28± 0.26 vs 2.26±0.25 vs 2.11±0.18; PBR 4-9: 1.25±0.17 vs 1.23±0.15 vs 1.15±0.10; PBR 10-19: 2.42±0.35 vs 2.47±0.33 vs 2.28±0.26; PBR 20-25: 3.07±0.52 vs 2.85±0.46 vs 2.60±0.36μm, respectively, p<0.05). The Lp (a) and the hyperlipidemia group demonstrated similar arterial stiffness and both groups greater than the control group (PWV: 11.96±2.41 vs 12.31±2.35 vs 9.98±2.29 m/sec; PP: 46.15±14.12 vs 48.27±14.52 vs 38.24±10.27mmHg; cSBP: 128.09±11.53 vs 130.27±11.72 vs 119.92±10.56 mmHg, respectively, p<0.05). Conclusion Participants with elevated Lp (a) levels present impaired arterial elasticity and glycocalyx integrity, similar to those with increased total cholesterol levels but normal Lp(a).