Objectives: Low-density lipoprotein cholesterol (LDL-C) is the main laboratory parameter used for the management of cardiovascular disease. The aim of this study was to compare measured LDL-C with LDL-C as calculated by the Friedewald, Martin/Hopkins, Vujovic, and Sampson formulas with regard to triglyceride (TG), LDL-C and non-high-density lipoprotein cholesterol (non-HDL-C)/TG ratio. Methods: The 1,209 calculated LDL-C results were compared with LDL-C measured using ultracentrifugation-precipitation (first study) and direct (second study) methods. The Passing-Bablok regression was applied to compare the methods. The percentage difference between calculated and measured LDL-C (total error) and the number of results exceeding the total error goal of 12% were established. Results: There was good correlation between the measurement and calculation methods (r 0.962–0.985). The median total error ranged from −2.7%/+1.4% (first/second study) for Vujovic formula to −6.7%/−4.3% for Friedewald formula. The numbers of underestimated results exceeding the total error goal of 12% were 67 (Vujovic), 134 (Martin/Hopkins), 157 (Samspon), and 239 (Friedewald). Less than 7% of those results were obtained for samples with TG >4.5 mmol/L. From 57% (Martin/Hopkins) to 81% (Vujovic) of underestimated results were obtained for samples with a non-HDL-C/TG ratio of <2.4. Conclusions: The Martin/Hopkins, Vujovic and Sampson formulas appear to be more accurate than the Friedewald formula. To minimize the number of significantly underestimated LDL-C results, we propose the implementation of risk categories according to non-HDL-C/TG ratio and suggest that for samples with a non-HDL-C/TG ratio of <1.2, the LDL-C level should not be calculated but measured independently from TG level.

BACKGROUND: Lipoprotein apheresis (LA) is an extracorporeal treatment that transiently reduces lipoprotein (a) [Lp(a)] by 60% and leads to an 80-92% reduction in major adverse cardiovascular events. LA has a significant impact on lipid profile in serum of patients with atherosclerotic cardiovascular disease. OBJECTIVE: To investigate the effects of LA on the composition of serum fatty acids (FAs), focusing on those which could have an impact on cardiovascular disease (CVD). METHODS: This is a prospective study in the First Department of Cardiology of the Medical University of Gdansk, Poland. Serum samples were collected from 28 patients before LA, just after the procedure, and 7 days after LA. Additionally, in a smaller group of patients, the samples were collected after a second tour of LA (2 weeks later), as well as after 1 year from the first procedure. The serum FA profile was analyzed using gas chromatography-mass spectrometry. RESULTS: After the LA procedure, a substantial change in serum FA composition along with lowdensity lipoprotein cholesterol (LDL-C) and Lp(a) decrease were observed 7 days after procedure, but these parameters returned to the values similar to those before procedure after 14 days. Very long-chain FAs (VLCFAs) and very long-chain monounsaturated FAs (VLC-MUFAs) were eluted at 57% and remained low even 7 days after LA (p = 0.027 and p < 0.001, respectively). We also observed an increase in the percentage of total branched-chain FAs (BCFAs) (p = 0.004) and anteiso BCFAs (p = 0.012) after LA. After 1 year of regular LA, a substantial decrease in serum VLC-MUFAs and n3 polyunsaturated LA (PUFAs) were noted. CONCLUSIONS: Decreased VLCFAs and VLC-MUFAs involved in CVD development remained low even 7 days after LA. An acute increase in the levels of anti-inflammatory BCFAs was observed. In turn long-term regular administration of LA substantially decreased VLC-MUFA and n3 PUFA. (c) 2023 National Lipid Association. Published by Elsevier Inc. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

Oxidative modifications of lipoproteins play a crucial role in the initiation of atherosclerotic cardiovascular diseases (ASCVDs). Nowadays, the one effective strategy for the treatment of patients with hyperlipoproteinemia(a) is lipoprotein apheresis (LA), which has a pleiotropic effect on reducing the risk of ASCVDs. The significance of oxidative susceptibility of the LDL fraction in ASCVDs has been extensively studied. Whether LA alters the susceptibility of lipoprotein(a) to oxidative modifications remains an unresolved issue. In this study, we isolated lipoprotein fractions by ultracentrifugation in patients with hyperlipoproteinemia(a) undergoing apheresis (LA group) at three time points and patients who were qualified for LA but did not consent to the procedure (non-LA group). We performed copper-mediated oxidation of Lp(a) and LDL fractions and determined autotaxin activity. After apheresis, we observed a lower susceptibility to oxidation of the Lp(a) and LDL fractions as expressed by the extended value of oxidation lag time, decreased slope of the oxidation curve, and decreased final concentration of conjugated dienes. No significant differences were found between these parameters before and 7 days after LA. Additionally, both patients undergoing and not undergoing LA had a significant correlation between autotaxin activity and all parameters characterizing susceptibility to oxidation in the Lp(a) fraction. Our results demonstrate that the pleiotropic effect of apheresis may be related to the reduced oxidative susceptibility of Lp(a) and LDL particles, which may influence the reduction in ASCVD risk in patients undergoing apheresis. The results of the rebound effect 7 days after LA will contribute to a better definition of apheresis frequency guidelines.