Assessment of Apolipoprotein(a) Isoform Size Using Phenotypic and Genotypic Methods

The functions of apolipoproteins and lipoproteins in health and disease

Lipoproteins and apolipoproteins are crucial in lipid metabolism, functioning as essential mediators in the transport of cholesterol and triglycerides and being closely related to the pathogenesis of multiple systems, including cardiovascular. Lipoproteins a (Lp(a)), as a unique subclass of lipoproteins, is a low-density lipoprotein(LDL)-like particle with pro-atherosclerotic and pro-inflammatory properties, displaying high heritability. More and more strong evidence points to a possible link between high amounts of Lp(a) and cardiac conditions like atherosclerotic cardiovascular disease (ASCVD) and aortic stenosis (AS), making it a risk factor for heart diseases. In recent years, Lp(a)'s role in other diseases, including neurological disorders and cancer, has been increasingly recognized. Although therapies aimed at low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) have achieved significant success, elevated Lp(a) levels remain a significant clinical management problem. Despite the limited efficacy of current lipid-lowering therapies, major clinical advances in new Lp(a)-lowering therapies have significantly advanced the field. This review, grounded in the pathophysiology of lipoproteins, seeks to summarize the wide-ranging connections between lipoproteins (such as LDL-C and HDL-C) and various diseases, alongside the latest clinical developments, special emphasis is placed on the pivotal role of Lp(a) in cardiovascular disease, while also examining its future potential and mechanisms in other conditions. Furthermore, this review discusses Lp(a)-lowering therapies and highlights significant recent advances in emerging treatments, advocates for further exploration into Lp(a)'s pathogenic mechanisms and its potential as a therapeutic target, proposing new secondary prevention strategies for high-risk individuals.

Advantages of using Genetically Elevated Lipoprotein(a) Levels in Predicting 5-Year Major Adverse Cardiovascular Events Relating to Coronary Artery Disease in Women

Background

This study aimed to investigate major adverse cardiovascular events (MACE) in patients with coronary artery disease (CAD) over 5 years, in general, and depending on sex, lipoprotein(a) level, and number of kringle IV type 2 (KIV-2) repeats in the Lipoprotein(A) (LPA) gene.

Methods

This study comprised 216 patients (120 women and 96 men) hospitalized with a diagnosis of "CAD, unstable angina IIB class". The three-point risk of MACEs was assessed over 5 years: cardiovascular death, non-fatal myocardial infarction, and stroke. The number of KIV-2 repeats in the LPA gene was determined by quantitative real-time polymerase chain reaction (qPCR).

Results

The relative risk of MACE in patients with elevated lipoprotein(a) (Lp(a)) was 2.0 (95% CI 1.04-3.87, p < 0.05) for quartile 4 (Q4) ≥ 48 mg/dL versus quartile 1 (Q1) ≤ 6 mg/dL. This was mainly attributable to an increase in men-relative risk (RR) 2.6 (95% CI 1.10-6.16, p < 0.05)-but not in women: RR 1.4 (95% CI 0.50-3.92). Mean lipoprotein(a) levels were inversely correlated with 42.5 and 7.5 for Q1 and Q4 KIV-2 repeat numbers, respectively. The relative risks of MACE for Q1 vs. Q4 KIV-2 repeats were as follows: 3.0 (95% CI 1.48-6.08, p < 0.001) for all patients; 3.0 (95% CI 1.20-6.55, p < 0.01) for men; 3.3 (95% CI 1.02-10.4, p < 0.05) for women.

Conclusions

Quantifying kringle IV type 2 repeat copy number in the LPA gene using qPCR more accurately reflects the risk of major adverse cardiovascular events within 5 years in women with coronary artery disease.

Recommendations of the Experts of the Polish Cardiac Society (PCS) and the Polish Lipid Association (PoLA) on the diagnosis and management of elevated lipoprotein(a) levels

Lipoprotein(a) [Lp(a)] is made up of a low-density lipoprotein (LDL) particle and a specific apolipoprotein(a). The blood concentration of Lp(a) is approximately 90% genetically determined, and the main genetic factor determining Lp(a) levels is the size of the apo(a) isoform, which is determined by the number of KIV2 domain repeats. The size of the apo(a) isoform is inversely proportional to the blood concentration of Lp(a). Lp(a) is a strong and independent cardiovascular risk factor. Elevated Lp(a) levels ≥ 50 mg/dl (≥ 125 nmol/l) are estimated to occur in more than 1.5 billion people worldwide. However, determination of Lp(a) levels is performed far too rarely, including Poland, where, in fact, it is only since the 2021 guidelines of the Polish Lipid Association (PoLA) and five other scientific societies that Lp(a) measurements have begun to be performed. Determination of Lp(a) concentrations is not easy due to, among other things, the different sizes of the apo(a) isoforms; however, the currently available certified tests make it possible to distinguish between people with low and high cardiovascular risk with a high degree of precision. In 2022, the first guidelines for the management of patients with elevated lipoprotein(a) levels were published by the European Atherosclerosis Society (EAS) and the American Heart Association (AHA). The first Polish guidelines are the result of the work of experts from the two scientific societies and their aim is to provide clear, practical recommendations for the determination and management of elevated Lp(a) levels.

Lifestyle and Lipoprotein(a) Levels: Does a Specific Counseling Make Sense?

Lipoprotein(Lp)(a) is a variant of low-density lipoprotein (LDL), bound to apolipoprotein B100, whose levels are associated with a significant increase in the risk of atherosclerosis-related cardiovascular events, but also to aortic stenosis and atrial fibrillation. Since plasma levels of Lp(a) are commonly considered resistant to lifestyle changes, we critically reviewed the available evidence on the effect of weight loss, dietary supplements, and physical activity on this risk factor. In our review, we observed that relevant body weight loss, a relatively high intake of saturated fatty acids, the consumption of red wine, and intense physical exercise seems to be associated with significantly lower plasma Lp(a) levels. On the contrary, foods rich in trans-unsaturated fatty acids are associated with increased Lp(a) levels. With regard to dietary supplements, coenzyme Q10, L-Carnitine, and flaxseed exert a mild but significant lowering effect on plasma Lp(a).

Estimating the Prevalence and Characteristics of Patients Potentially Eligible for Lipoprotein(a)-Lowering Therapies in a Real-World Setting

High lipoprotein(a) (Lp(a)) plasma levels are significantly associated with an increased risk of developing atherosclerotic cardiovascular diseases (ASCVD). The aim of this analysis was to estimate the prevalence and characteristics of patients potentially eligible for Lp(a)-lowering therapies in a real-world setting (i.e., patients with ASCVD and Lp(a) levels > 70 mg/dL). For this reason, we pooled data from a large cohort of Italian outpatients (N = 5961; men: 2879, women: 3982) with dyslipidemia. A binary logistic regression analysis was used to determine the significant predictors of ASCVD in the cohort, which were age (Odds Ratio (OR): 1.158, 95% Confidence Interval (CI): 1.114 to 1.203, p < 0.001), low-density lipoprotein cholesterol at entry (OR: 1.989, 95% CI: 1.080 to 1.198, p = 0.020) and Lp(a) (OR: 1.090, 95% CI: 1.074 to 1.107, p < 0.001). In our cohort, almost half of patients with ASCVD (44.7%) may be eligible to be treated with Lp(a)-lowering agents. Interestingly, patients who do not meet the treatment criteria despite high Lp(a) (50-70 mg/dL), respectively, account for 4.7% and 7.3% of those in primary and secondary ASCVD prevention. In conclusion, in our large cohort of outpatients with dyslipidemia, the prevalence of individuals with ASCVD and very high Lp(a) plasma levels is quite high, even with a conservative estimation.

Sex X Time Interactions in Lp(a) and LDL-C Response to Evolocumab

The aim of this study was to evaluate whether there were significant sex x time interactions in lipoprotein(a) (Lp(a)) and low-density lipoprotein cholesterol (LDL-C) response to treatment with the Proprotein Convertase Subtilisin/Kexin type 9 inhibitor (PCSK9i) Evolocumab, in a real-life clinical setting. For this purpose, we pooled data from 176 outpatients (Men: 93; Women: 83) clinically evaluated at baseline and every six months after starting Evolocumab. Individuals who had been on PCSK9i for less than 30 months and nonadherent patients were excluded from the analysis. Over time, absolute values of Lp(a) plasma concentrations significantly decreased in the entire cohort (p-value < 0.001) and by sex (p-value < 0.001 in men and p-value = 0.002 in and women). However, there were no sex-related significant differences. Absolute plasma concentrations of LDL-C significantly decreased over time in the entire cohort and by sex (p-value < 0.001 always), with greater improvements in men compared to women. The sex x time interaction was statistically significant in LDL-C (all p-values < 0.05), while absolute changes in Lp(a) were not influenced by either sex or time (all p-value > 0.05). Our data partially reinforce the presence of differences in response to treatment to PCSK9i between men and women and are essential to gain a better understanding of the relationship between LDL-C and Lp(a) lowering in response to PCSK9i. Further research will clarify whether these sex-related significant differences translate into a meaningful difference in the long-term risk of ASCVD.

Cardiac Sarcoidosis: A Contemporary Concept of Forgotten Granulomatosis

Sarcoidosis is a complex multisystem inflammatory granulomatous disease that can affect any organ, with a wide range of clinical presentations. A significant number of patients with systemic sarcoidosis may also have cardiac involvement. Clinical manifestations of cardiac sarcoidosis can include various rhythm and conduction disturbances, as well as heart failure. The structure of sarcoid granulomas is similar to that of tuberculous granulomas, but in contrast, they lack caseous necrosis. Tissue changes in sarcoidosis tissues depend on the stage of development of the disease, progressing from pathological process: macrophage-lymphocytic infiltration to epithelioid cell granuloma formation, and fibrosis. Granulomas can be found in any part of the myocardium, with the most common locations being the free wall of the left ventricle, the basal part of the interventricular septum, and the interatrial septum. Vasculopathy of the pulmonary circulation and coronary arteries is often observed. Advancements in diagnostic imaging techniques, such as computer tomography and magnetic resonance imaging, have facilitated the verification of cardiac sarcoidosis. This article presents an analysis of updated information on cardiac sarcoidosis by a multidisciplinary working group.