Elevated apolipoprotein B as a risk-enhancing factor in 2018 cholesterol guidelines

Role of apolipoprotein B in the clinical management of cardiovascular risk in adults: An expert clinical consensus from the national lipid association

This National Lipid Association (NLA) Expert Clinical Consensus provides an overview of the physiologic and clinical considerations regarding the role of apolipoprotein B (apoB) measurement to guide clinical care based on the available scientific evidence and expert opinion. ApoB represents the total concentration of atherogenic lipoprotein particles in the circulation and more accurately reflects the atherogenic burden of lipoproteins when compared to low-density lipoprotein cholesterol (LDL-C). ApoB is a validated clinical measurement that augments the information found in a standard lipoprotein lipid panel; therefore, there is clinical value in using apoB in conjunction with a standard lipoprotein lipid profile when assessing risk and managing lipid-lowering therapy (LLT). ApoB has been shown to be superior to LDL-C in risk assessment both before and during treatment with LLT. In individuals, there can be discordance between levels of LDL-C and apoB, as well as LDL-C and non-high-density lipoprotein cholesterol (non-HDL-C), despite high levels of population-wide correlation. When there is discordance between LDL-C and apoB, or LDL-C and non-HDL-C, atherosclerotic cardiovascular disease risk generally aligns better with apoB or non-HDL-C. Additionally, apoB can be used in tandem with standard lipoprotein lipid measurements to diagnose distinct lipoprotein phenotypes. ApoB testing can inform clinical prognosis and care, as well as enable family cascade screening, when an inherited lipoprotein syndrome is identified. The NLA and other organizations will continue to educate clinicians about the role of apoB measurement in improving clinical risk assessment and dyslipidemia management. An urgent need exists to improve access and reimbursement for apoB testing.

European guidelines for the treatment of dyslipidaemias: New concepts and future challenges

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of mortality and morbidity worldwide. Low-density lipoprotein cholesterol (LDL-C) is one of the most important causal factors for ASCVD. Based on the evidence of the clinical benefits of lowering LDL-C, the current 2019 European Society of Cardiology (ESC) and European Atherosclerosis Society (EAS) guidelines provide guidance for optimal management of people with dyslipidaemia. These guidelines include new and revised concepts, with a general tightening of LDL-C goals to be achieved, especially for patients at high and very high cardiovascular risk, based on the results of clinical trials of the recently approved drugs for the treatment of hypercholesterolaemia. However, some issues are still open for discussion. Among others, the concept of lifetime exposure to elevated LDL-C levels will probably drive the pharmacological approach and future guidelines. In addition, other factors such as non-HDL-C, apolipoprotein B, and lipoprotein(a) are becoming increasingly important in determining cardiovascular risk. Finally, there is the question of whether combination therapy should be used as the first step to maximise the effectiveness of the pharmacological approach, avoiding the stepwise approach, which is likely to have a detrimental effect on adherence. Given the ever-changing landscape and the availability of new drugs targeting other important lipids, future guidelines will need to consider all these issues.

Best practice for LDL-cholesterol: when and how to calculate

The lipid profile is important in the risk assessment for cardiovascular disease. The lipid profile includes total cholesterol, high-density lipoprotein (HDL)-cholesterol, triglycerides (TGs) and low-density lipoprotein (LDL)-cholesterol (LDL-C). LDL-C has traditionally been calculated using the Friedewald equation (invalid with TGs greater than 4.5 mmol/L and is based on the assumption that the ratio of TG to cholesterol in very- low-density lipoprotein (VLDL) is 5 when measured in mg /dL). LDL-C can be quantified with a reference method, beta-quantification involving ultracentrifugation and this is unsuitable for routine use. Direct measurement of LDL-C was expected to provide a solution with high TGs. However, this has some challenges because of a lack of standardisation between the reagents and assays from different manufacturers as well as the additional costs. Furthermore, mild hypertriglyceridaemia also distorts direct LDL-C measurements. With the limitations of the Friedewald equation, alternatives have been derived. Newer equations include the Sampson-National Institutes of Health (NIH) equation 2 and the Martin-Hopkins equation. The Sampson-NIH2 equation was derived using beta-quantification in a population with high TG and multiple least squares regression to calculate VLDL-C, using TGs and non-HDL-C as independent variables. These data were used in a second equation to calculate LDL-C. The Sampson-NIH2 equation can be used with TGs up to 9 mmol/L. The Martin-Hopkins equation uses a 180 cell stratification of TG/non-HDL-C to determine the TG:VLDL-C ratio and can be used with TGs up to 4.5 mmol/L. Recently, an extended Martin-Hopkins equation has become available for TGs up to 9.04 mmol/L.This article discusses the best practice approach to calculating LDL-C based on the available evidence.

New and Emerging Therapies for Dyslipidemia

Atherosclerotic cardiovascular disease (ASCVD) continues to represent a growing global health challenge. Despite guideline-recommended treatment of ASCVD risk, including antihypertensive, high-intensity statin therapy, and antiaggregant agents, high-risk patients, especially those with established ASCVD and patients with type 2 diabetes, continue to experience cardiovascular events. Recent years have brought significant developments in lipid and atherosclerosis research. Several lipid drugs owe their existence, in part, to human genetic evidence. Here, the authors briefly review the mechanisms, the effect on lipid parameters, and safety profiles of some of the most promising new lipid-lowering approaches that will be soon available in our daily clinical practice.

Lipoprotein(a): A Genetically Determined, Causal, and Prevalent Risk Factor for Atherosclerotic Cardiovascular Disease: A Scientific Statement From the American Heart Association

High levels of lipoprotein(a) [Lp(a)], an apoB100-containing lipoprotein, are an independent and causal risk factor for atherosclerotic cardiovascular diseases through mechanisms associated with increased atherogenesis, inflammation, and thrombosis. Lp(a) is predominantly a monogenic cardiovascular risk determinant, with ≈70% to ≥90% of interindividual heterogeneity in levels being genetically determined. The 2 major protein components of Lp(a) particles are apoB100 and apolipoprotein(a). Lp(a) remains a risk factor for cardiovascular disease development even in the setting of effective reduction of plasma low-density lipoprotein cholesterol and apoB100. Despite its demonstrated contribution to atherosclerotic cardiovascular disease burden, we presently lack standardization and harmonization of assays, universal guidelines for diagnosing and providing risk assessment, and targeted treatments to lower Lp(a). There is a clinical need to understand the genetic and biological basis for variation in Lp(a) levels and its relationship to disease in different ancestry groups. This scientific statement capitalizes on the expertise of a diverse basic science and clinical workgroup to highlight the history, biology, pathophysiology, and emerging clinical evidence in the Lp(a) field. Herein, we address key knowledge gaps and future directions required to mitigate the atherosclerotic cardiovascular disease risk attributable to elevated Lp(a) levels.

Apolipoprotein B and Cardiovascular Disease: Biomarker and Potential Therapeutic Target

Apolipoprotein (apo) B, the critical structural protein of the atherogenic lipoproteins, has two major isoforms: apoB48 and apoB100. ApoB48 is found in chylomicrons and chylomicron remnants with one apoB48 molecule per chylomicron particle. Similarly, a single apoB100 molecule is contained per particle of very-low-density lipoprotein (VLDL), intermediate density lipoprotein, LDL and lipoprotein(a). This unique one apoB per particle ratio makes plasma apoB concentration a direct measure of the number of circulating atherogenic lipoproteins. ApoB levels indicate the atherogenic particle concentration independent of the particle cholesterol content, which is variable. While LDL, the major cholesterol-carrying serum lipoprotein, is the primary therapeutic target for management and prevention of atherosclerotic cardiovascular disease, there is strong evidence that apoB is a more accurate indicator of cardiovascular risk than either total cholesterol or LDL cholesterol. This review examines multiple aspects of apoB structure and function, with a focus on the controversy over use of apoB as a therapeutic target in clinical practice. Ongoing coronary artery disease residual risk, despite lipid-lowering treatment, has left patients and clinicians with unsatisfactory options for monitoring cardiovascular health. At the present time, the substitution of apoB for LDL-C in cardiovascular disease prevention guidelines has been deemed unjustified, but discussions continue.

Public health guidelines should recommend reducing saturated fat consumption as much as possible: YES

Based on decades of research, there is strong evidence that supports ongoing dietary recommendations to decrease intakes of SFAs and, more recently, to replace SFAs with unsaturated fat, including PUFAs and MUFAs. Epidemiologic research has shown that replacement of SFAs with unsaturated fat, but not refined carbohydrate and added sugars, is associated with a reduction in coronary heart disease events and death. There is much evidence from controlled clinical studies demonstrating that SFAs increase LDL cholesterol, a major causal factor in the development of cardiovascular disease. When each (nonprotein) dietary macronutrient isocalorically replaces SFA, the greatest LDL-cholesterol-lowering effect is seen with PUFA, followed by MUFA, and then total carbohydrate. New research on full-fat dairy products high in saturated fat, particularly fermented dairy foods, demonstrates some benefits for cardiometabolic diseases. However, compared with food sources of unsaturated fats, full-fat dairy products increase LDL cholesterol. Thus, current dietary recommendations to decrease SFA and replace it with unsaturated fat should continue to the basis for healthy food-based dietary patterns.

A Phase IV, Randomized, Double-Blind, Placebo-Controlled Crossover Study of the Effects of Ustekinumab on Vascular Inflammation in Psoriasis (the VIP-U Trial)

Psoriasis is a T helper type 17 autoimmune disease associated with an increased risk cardiovascular events and mortality. Ustekinumab, an antibody to p40, blocks cytokines IL-12 and IL-23, and is a highly effective and safe treatment for psoriasis. We conducted a randomized double-blinded placebo-controlled trial to determine the effect of ustekinumab on aortic vascular inflammation (AVI) measured by imaging, and key biomarkers of inflammation, lipid, and glucose metabolism in the blood of patients with moderate-to-severe psoriasis. A total of 43 patients were randomized, and at week 12, ustekinumab-treated patients had a -18.65% (95% confidence interval = -29.45% to -7.85%) reduction in AVI, a reduction in inflammatory biomarkers, and an increase in apolipoprotein B lipoproteins compared with placebo. At week 12, placebo patients were crossed over such that all patients received ustekinumab for 52 weeks. At the end of 52 weeks of ustekinumab treatment, there was no change in AVI compared with baseline, inflammatory markers were reduced, and there were increases in selected measures of lipids and leptin. These results show that blockade of IL-12 and/or IL-23 may transiently reduce AVI, with more durable reduction in inflammatory cytokines associated with cardiovascular disease.