PCSK9 and lipoprotein (a) levels are two predictors of coronary artery calcification in asymptomatic patients with familial hypercholesterolemia

Proprotein convertase subtilisin/kexin type 9 (PCSK9) and clinical outcomes in dialysis patients

BACKGROUND

Proprotein convertase subtilisin/kexin type 9 (PCSK9), a factor accelerating the degradation of LDL receptors, was associated with a gender-dependent risk for cardiovascular (CV) events in the general population and with all-cause and CV mortality in two relatively small studies in black Africans and South Korean haemodialysis patients. The effect modification by gender was untested in these studies.

METHODS

The study enrolled 1188 dialysis patients from the Prospective Registry of The Working Group of Epidemiology of Dialysis Region Calabria (PROGREDIRE) cohort. PCSK9 was measured by colorimetric enzyme-linked immunosorbent assay. The primary outcomes were all-cause and CV mortality. Statistical analysis included Cox regression analysis and effect modification analysis.

RESULTS

During a median 2.9-year follow-up, out of 494 deaths, 278 were CV-related. In unadjusted analyses, PCSK9 levels correlated with increased all-cause (HRfor1ln unit increase: 1.23, 95% CI 1.06-1.43, p =.008) and CV mortality (HRfor1ln unit increase: 1.26, 95% CI 1.03-1.54, p =.03). After multivariate adjustment, these associations were no longer significant (all-cause mortality, HRfor 1 ln unit increase: 1.16, 95% CI .99-1.36, p =.07; CV mortality, HRfor1ln unit increase: 1.18, 95% CI .95-1.46, p =.14). However, in fully adjusted interaction analyses, a doubling in the risk of this outcome in women was registered (Women, HRfor1ln unit increase: 1.88, 95% CI 1.27-2.78, p =.002; Men, HRfor1ln unit increase: 1.07, 95% CI .83-1.38, p =.61; p for effect modification: .02).

CONCLUSIONS

PCSK9 levels are unrelated to all-cause mortality in haemodialysis patients but, like in studies of the general population, independently of other risk factors, entail a doubling in the risk of CV events in women in this population.

The association of lipoprotein(a) and coronary artery calcium in asymptomatic patients: a systematic review and meta-analysis

AIMS

Lipoprotein(a) [Lp(a)] is an atherogenic lipid particle associated with increased risk for coronary heart disease (CHD) events. Coronary artery calcium (CAC) score is a tool to diagnose subclinical atherosclerosis and guide clinical decision-making for primary prevention of CHD. Studies show conflicting results concerning the relationship between Lp(a) and CAC in asymptomatic populations. We conducted a meta-analysis to evaluate the association of Lp(a) and CAC in asymptomatic patients.

METHODS AND RESULTS

We systematically searched PubMed, Embase, and Cochrane until April 2023 for studies evaluating the association between Lp(a) and CAC in asymptomatic patients. We evaluated CAC > 0 Agatston units, and CAC ≥ 100. Lp(a) was analysed as a continuous or dichotomous variable. We assessed the association between Lp(a) and CAC with pooled odds ratios (OR) adopting a random-effects model. A total of 23 105 patients from 18 studies were included in the meta-analysis with a mean age of 55.9 years, 46.4% female. Elevated Lp(a) increased the odds of CAC > 0 [OR 1.31; 95% confidence intervals (CI) 1.05-1.64; P = 0.02], CAC ≥100 (OR 1.29; 95% CI 1.01-1.65; P = 0.04; ), and CAC progression (OR 1.43; 95% CI 1.20-1.70; P < 0.01; ). For each increment of 1 mg/dL in Lp(a) there was a 1% in the odds of CAC > 0 (OR 1.01; 95% CI 1.01-1.01; P < 0.01).

CONCLUSION

Our findings of this meta-analysis suggest that Lp(a) is positively associated with a higher likelihood of CAC. Higher Lp(a) levels increased the odds of CAC >0. These data support the concept that Lp(a) is atherogenic, although with high heterogeneity and a low level of certainty.

PROTOCOL REGISTRATION

CRD42023422034.

KEY FINDINGS

Asymptomatic patients with elevated Lp(a) had 31% higher chances of having any coronary calcification (CAC > 0) and 29% higher chances of having more advanced calcification (CAC > 100). It increased the chances of having progression of coronary calcification over time by 43%. For each 1 mg/dL of Lp(a) there was an increment of 1% chance of having coronary calcification.

Long-Term Efficacy and Tolerability of PCSK9 Targeted Therapy: A Review of the Literature

Increased plasma levels of low-density lipoprotein cholesterol (LDL-C) are causally associated with atherosclerotic cardiovascular disease (ASCVD), and statins that lower LDL-C have been the cornerstone of ASCVD prevention for decades. However, guideline-recommended LDL-C targets are not achieved in about 60% of statin users. Proprotein convertase subtilisin/kexin type 9 (PCSK9)-targeted therapy effectively lowers LDL-C levels and has been shown to reduce ASCVD risk. A growing body of scientific and clinical evidence shows that PCSK9-targeted therapy offers an excellent safety and tolerability profile with a low incidence of side effects in the short term. In this review, we present and discuss the current clinical and scientific evidence pertaining to the long-term efficacy and tolerability of PCSK9-targeted therapy.

The association of lipoprotein (a) with coronary artery calcification: A systematic review and meta-analysis

BACKGROUND AND AIMS

Coronary artery calcification (CAC) is a crucial pathophysiological characteristic of atherosclerosis. The association between lipoprotein (a) [Lp(a)] and CAC is inconsistent. We aimed to assess the relationship between Lp(a) and CAC by exploring the association between elevated Lp(a) and CAC prevalence, the relationship between Lp(a) level and CAC prevalence, and the correlation between elevated Lp(a) and CAC progression.

METHODS

We searched the PubMed, Web of Science, and EMBASE databases up to November 01, 2023. Studies exploring the association between serum Lp(a) and CAC (quantified using the Agatston score) were included. Association between Lp(a) level or elevated Lp(a) (higher than the cutoff values of 30 mg/dL, 50 mg/dL, or the highest quartile ranging from 33 to 38.64 mg/dL) and prevalence [CAC score >0 or >100, log (CAC score+1) >0] or progression (an increase in CAC score >0 or ≥100) of CAC were analysed. Odds ratios and 95% confidence intervals were calculated using a random-effects model.

RESULTS

40,073 individuals from 17 studies were included. Elevated Lp(a) was associated with a higher prevalence of CAC (OR, 1.31; 95% CI, 1.06 to 1.61; p = 0.01). As a continuous variable, Lp(a) level was positively correlated with the prevalence of CAC (OR, 1.05; 95% CI, 1.02 to 1.08; p = 0.003). Furthermore, elevated Lp(a) was associated with greater CAC progression (OR, 1.54; 95% CI, 1.23 to 1.92; p = 0.0002).

CONCLUSIONS

This meta-analysis suggested that Lp(a) is associated with prevalence and progression of CAC. Further studies are required to explore whether Lp(a)-lowering therapy could prevent or inhibit CAC, ultimately reducing coronary artery disease risk.

Lipoprotein(a) and coronary artery calcium in comparison with other lipid biomarkers: The multi-ethnic study of atherosclerosis

BACKGROUND

Coronary artery calcium (CAC) scoring is often used for atherosclerotic cardiovascular disease (ASCVD) risk stratification in individuals with elevated lipoprotein(a) [Lp(a)].

OBJECTIVE

To evaluate associations between Lp(a) and baseline CAC (volume/density) and CAC progression compared to other lipid biomarkers.

METHODS

We utilized data from the Multi-Ethnic Study of Atherosclerosis (MESA), a cohort study of individuals without clinical ASCVD, excluding statin users. We evaluated the associations between Lp(a), low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C), triglycerides, total cholesterol, apolipoprotein B, and non-HDL-C with baseline CAC and annual CAC progression using multivariable ordinal regression with adjustment for ASCVD risk factors. Analyses were also stratified by median age.

RESULTS

In 5,597 participants (2,726 at median 9.5-year follow-up), Lp(a) was not associated with baseline CAC volume or density and was modestly associated with volume progression (OR 1.11, 95% CI 1.03-1.21). However, other biomarkers were positively associated with baseline volume and volume progression (LDL-C: OR 1.26, 95% CI: 1.19-1.33 and OR 1.22, 95% CI: 1.15-1.30, respectively), except HDL-C which was inversely associated. LDL-C, total cholesterol and non-HDL-C were inversely associated with baseline density. In participants <62 years of age, Lp(a) was modestly associated with baseline CAC volume (OR 1.10, 95% CI: 1.00-1.20) and volume progression (OR 1.16 95% CI: 1.04-1.30).

CONCLUSIONS

In contrast to other lipid biomarkers, Lp(a) was not associated with baseline CAC volume or density and was only modestly associated with volume progression. Our findings suggest that Lp(a) is not as robustly associated with CAC as other lipid biomarkers.

Relationship between Serum Proprotein Convertase Subtilisin/Kexin Type 9 Concentration and Prevalence of Coronary Artery Calcium in a Community-Based Sample of Japanese Men

AIMS

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a promising new target for reducing low-density lipoprotein cholesterol (LDL-C) and cardiovascular events in high-risk patients. However, the influence of circulating PCSK9 concentration on atherosclerotic plaque formation in the general population remains unknown. We assessed the relationship between serum PCSK9 concentration and coronary artery calcium (CAC) prevalence in the general population.

METHODS

Community-dwelling Japanese men (n=622) aged 46-82 years without a history of cardiovascular disease and lipid-lowering medications were included. Serum PCSK9 concentration and CAC score were measured using the Agatston method, and the multivariable analysis was used to assess their association. CAC was defined as an Agatston score of ＞10. We conducted further analysis stratified by age (＜60, 60-69, and ≥ 70 years).

RESULTS

The average age, LDL-C, and median serum PCSK9 concentration were 68 years, 122 mg/dL, and 240 ng/mL, respectively. After multivariable adjustment for traditional cardiovascular risk factors, no significant association was observed between serum PCSK9 concentration and CAC prevalence (adjusted relative risk [aRR] 1.05, 95% confidence interval [CI] 0.97-1.13). With age stratification, serum PCSK9 concentration was significantly associated with CAC prevalence in men aged ＜60 years (aRR 1.38, 95% CI 1.01-1.88) but not in men aged 60-69 years (aRR 0.96, 95% CI 0.85-1.10) or ≥ 70 years (aRR 1.08, 95% CI 0.99-1.19).

CONCLUSIONS

A higher serum PCSK9 concentration was associated with a higher CAC prevalence in men aged ＜60 years, which was independent of traditional cardiovascular risk factors.

Effect of Alirocumab on Coronary Calcification in Patients With Coronary Artery Disease

Background

Proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitors have been documented with significantly reduction in LDL cholesterol levels and cardiovascular events. However, evidence regarding the impact of PCSK9 inhibitors on coronary calcification is limited.

Methods

Eligible patients with intermediate coronary lesions and elevated LDL cholesterol values were randomized to either alirocumab 75 mg Q2W plus statin (atorvastatin 20 mg/day or rosuvastatin 10 mg/day) therapy or standard statin therapy. Calcium score based on coronary computed tomographic angiography at baseline and follow up were compared.

Results

Compared with baseline levels, LDL cholesterol were significantly decreased in both groups, while the absolute reduction of LDL cholesterol levels were higher in patients treated with alirocumab (1.69 ± 0.52 vs. 0.92 ± 0.60, P < 0.0001). Additionally, patients in alirocumab group demonstrated a significant reduction of Lp(a) levels, whereas it was not observed in the standard statin group. Notably, greater increases in the percentage changes of CAC score (10.6% [6.3–23.3] vs. 2.9% [−6.7–8.3]; P < 0.0001) were observed in the statin group compared to the alirocumab group. Consistently, CAC progression was significantly lower in the alirocumab group than in the standard statin group (0.6 ± 2.2% vs. 2.7 ± 2.3%; P = 0.002).

Conclusions

Study indicated that administration of the PCSK9 inhibitors to statins produced significantly lower rate of CAC progression in patients with coronary artery disease. Further studies with CAC progression and their clinical outcomes are needed.

Trial Registration

ClinicalTrials.gov, Identifier: NCT04851769.

Independent Association of Lipoprotein(a) and Coronary Artery Calcification With Atherosclerotic Cardiovascular Risk

BACKGROUND

Elevated lipoprotein(a) [Lp(a)] and coronary artery calcium (CAC) score are individually associated with increased atherosclerotic cardiovascular disease (ASCVD) risk but have not been studied in combination.

OBJECTIVES

This study sought to investigate the independent and joint association of Lp(a) and CAC with ASCVD risk.

METHODS

Plasma Lp(a) and CAC were measured at enrollment among asymptomatic participants of the MESA (Multi-Ethnic Study of Atherosclerosis) (n = 4,512) and DHS (Dallas Heart Study) (n = 2,078) cohorts. Elevated Lp(a) was defined as the highest race-specific quintile, and 3 CAC score categories were studied (0, 1-99, and ≥100). Associations of Lp(a) and CAC with ASCVD risk were evaluated using risk factor-adjusted Cox regression models.

RESULTS

Among MESA participants (61.9 years of age, 52.5% women, 36.8% White, 29.3% Black, 22.2% Hispanic, and 11.7% Chinese), 476 incident ASCVD events were observed during 13.2 years of follow-up. Elevated Lp(a) and CAC score (1-99 and ≥100) were independently associated with ASCVD risk (HR: 1.29; 95% CI: 1.04-1.61; HR: 1.68; 95% CI: 1.30-2.16; and HR: 2.66; 95% CI: 2.07-3.43, respectively), and Lp(a)-by-CAC interaction was not noted. Compared with participants with nonelevated Lp(a) and CAC = 0, those with elevated Lp(a) and CAC ≥100 were at the highest risk (HR: 4.71; 95% CI: 3.01-7.40), and those with elevated Lp(a) and CAC = 0 were at a similar risk (HR: 1.31; 95% CI: 0.73-2.35). Similar findings were observed when guideline-recommended Lp(a) and CAC thresholds were considered, and findings were replicated in the DHS.

CONCLUSIONS

Lp(a) and CAC are independently associated with ASCVD risk and may be useful concurrently for guiding primary prevention therapy decisions.

Lipoprotein (a)-mediated vascular calcification: population-based and in vitro studies

BACKGROUND

Lipoprotein (a) [Lp(a)] is a causal risk factor for cardiovascular diseases, while its role in vascular calcification has not been well-established. Here, we investigated an association of Lp(a) with vascular calcification using population-based and in vitro study designs.

METHODS

A total of 2806 patients who received coronary computed tomography were enrolled to assess the correlation of Lp(a) with the severity of coronary artery calcification (CAC). Human aortic smooth muscle cells (HASMCs) were used to explore mechanisms of Lp(a)-induced vascular calcification.

RESULTS

In the population study, Lp(a) was independently correlated with the presence and severity of CAC (all p < 0.05). In vitro study showed that cell calcific depositions and alkaline phosphatase (ALP) activity were increased and the expression of pro-calcific proteins, including bone morphogenetic protein-2 (BMP2) and osteopontin (OPN), were up-regulated by Lp(a) stimulation. Interestingly, Lp(a) activated Notch1 signaling, resulting in cell calcification, which was inhibited by the Notch1 signaling inhibitor, DAPT. Lp(a)-induced Notch1 activation up-regulated BMP2-Smad1/5/9 pathway. In contrast, Noggin, an inhibitor of BMP2-Smad1/5/9 pathway, significantly blocked Lp(a)-induced HASMC calcification. Notch1 activation also induced translocation of nuclear factor-κB (NF-κB) accompanied by OPN overexpression and elevated inflammatory cytokines production, while NF-κB silencing alleviated Lp(a)-induced vascular calcification.

CONCLUSIONS

Elevated Lp(a) concentrations are independently associated with the presence and severity of CAC and the impact of Lp(a) on vascular calcification is involved in the activation of Notch1-NF-κB and Notch1-BMP2-Smad1/5/9 pathways, thus implicating Lp(a) as a potential novel therapeutic target for vascular calcification.

How Can We Identify Very High-Risk Heterozygous Familial Hypercholesterolemia?

Heterozygous familial hypercholesterolemia (HeFH) is a genetic disorder that elevates low-density lipoprotein cholesterol and increases the risk of premature atherosclerotic cardiovascular disease (ASCVD). However, despite their atherogenic lipid profiles, the cardiovascular risk of HeFH varies in each individual. Their variety of phenotypic features suggests the need for better risk stratification to optimize their therapeutic management. The current review summarizes three potential approaches, including (1) definition of familial hypercholesterolemia (FH)-related risk scores, (2) genetic analysis, and (3) biomarkers. The International Atherosclerosis Society has recently proposed a definition of severe FH to identify very high-risk HeFH subjects according to their clinical characteristics. Furthermore, published studies have shown the association of FH-related genetic phenotypes with ASCVD, which indicates the genetic analysis’s potential to evaluate individual cardiovascular risks. Biomarkers reflecting disease activity have been considered to predict the formation of atherosclerosis and the occurrence of ASCVD in HeFH subjects. Incorporating these risk stratifications will be expected to allocate adequate intensity of lipid-lowering therapies in HeFH subjects, which ultimately improves cardiovascular outcomes.

PCSK9 Gene Participates in the Development of Primary Dyslipidemias

Dyslipidemias are a group of diseases, which are characterized by abnormal blood concentrations of cholesterol, triglycerides and/or low-density lipoprotein-cholesterol (LDL-c). Dyslipidemia is a determinant condition for the progress of an atherosclerotic plaque formation. The resulting atherogenicity is due to at least two mechanisms: first, to the accumulation in the plasma of lipid particles that have the capacity to alter the function of the endothelium and deposit at the atheromatous plaque, and second, at an insufficient concentration of multifactorial type of high density lipoprotein-cholesterol (HDL-c), whose function is to protect against the development of atherosclerosis. Its highest prevalence is encountered among individuals with diabetes, hypertension or overweight. Hyperlipidemia is one of the main predisposing factors for the development of cardiovascular disease. Hyperlipidemia can be the result of a genetic condition, the secondary expression of a primary process or the consequence of exogenous factors (food, cultural, socio-economic, etc.), all of which lead to the elevation of plasma lipid levels. The objective of this study was to carry out an analysis of the genes involved in the development of dyslipidemias that lead to cardiovascular disease with special emphasis on the proprotein convertase subtilin/kexin type 9 (PCSK9) gene. The PCSK9 gene participates in the development of primary dyslipidemias, mainly familial hypercholesterolemia, currently the pharmacological treatment of choice to reduce LDL-c are statins, however, it has been observed that these have been insufficient to eliminate cardiovascular risk, especially in subjects with primary forms of hypercholesterolemia related to genetic mutations, or statin intolerance.

Relationship between Circulating PCSK9 and Markers of Subclinical Atherosclerosis-The IMPROVE Study

(1) Background and purpose: circulating proprotein convertase subtilisin/kexin type 9 (PCSK9) is one of the key regulators of cholesterol metabolism. Despite this, its role as a player in atherosclerosis development is still matter of debate. Here, we investigated the relationships between this protein and several markers of subclinical atherosclerosis. (2) Methods: the IMPROVE study enrolled 3703 European subjects (54–79 years; 48% men; with ≥3 vascular risk factors), asymptomatic for cardiovascular diseases. PCSK9 levels were measured by ELISA. B-mode ultrasound was used to measure markers of carotid subclinical atherosclerosis. (3) Results: in the crude analysis, PCSK9 levels were associated with several baseline measures of carotid intima-media thickness (cIMT) (all p < 0.0001); with cIMT change over time (Fastest-IMTmax-progr) (p = 0.01); with inter-adventitia common carotid artery diameter (ICCAD) (p < 0.0001); and with the echolucency (Grey Scale Median; GSM) of both carotid plaque and plaque-free common carotid IMT (both p < 0.0001). However, after adjustment for age, sex, latitude, and pharmacological treatment, all the afore-mentioned correlations were no longer statistically significant. The lack of correlation was also observed after stratification for sex, latitude, and pharmacological treatments. (4) Conclusions: in subjects who are asymptomatic for cardiovascular diseases, PCSK9 plasma levels do not correlate with vascular damage and/or subclinical atherosclerosis of extracranial carotid arteries.

Inclisiran-Silencing the Cholesterol, Speaking up the Prognosis

The reduction of circulating low-density lipoprotein-cholesterol (LDL-C) is a primary target in cardiovascular risk reduction due to its well-established benefits in terms of decreased mortality. Despite the use of statin therapy, 10%–20% of high- and very-high-risk patients do not reach their LDL-C targets. There is an urgent need for improved strategies to manage dyslipidemia, especially among patients with homozygous familial hypercholesterolemia, but also in patients with established cardiovascular disease who fail to achieve LDL goals despite combined statin, ezetimibe, and PCSK9 inhibitor (PCSK9i) therapy. Inclisiran is a disruptive, first-in-class small interfering RNA (siRNA)-based therapeutic developed for the treatment of hypercholesterolemia that inhibits proprotein convertase subtilisin–kexin type 9 (PCSK9) synthesis, thereby upregulating the number of LDL receptors on the hepatocytes, thus lowering the plasma LDL-C concentration. Inclisiran decreases the LDL-C levels by over 50% with one dose every 6 months, making it a simple and well-tolerated treatment strategy. In this review, we summarize the general information regarding (i) the role of LDL-C in atherosclerotic cardiovascular disease, (ii) data regarding the role of PCSK9 in cholesterol metabolism, (iii) pleiotropic effects of PCSK9, and (iv) the effects of PCSK9 silencing. In addition, we focus on inclisiran, in terms of its (i) mechanism of action, (ii) biological efficacy and safety, (iii) results from the ORION trials, (iv) benefits of its combination with statins, and (v) its potential future role in atherosclerotic cardiovascular disease.

PCSK9 and atherosclerosis: Looking beyond LDL regulation

Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) is involved in cholesterol homeostasis. After binding to the complex low-density lipoprotein (LDL)-receptor, PCSK9 induces its intracellular degradation, thus reducing serum LDL clearance. In addition to the well-known activity on the hepatic LDL receptor-mediated pathway, PCSK9 has been, however, associated with vascular inflammation in atherogenesis. Indeed, PCSK9 is expressed by various cell types that are involved in atherosclerosis (e.g. endothelial cells, smooth muscle cells and macrophages) and is detected inside human atherosclerotic plaques. We here analyse the biology of PCSK9 and its possible involvement in molecular processes involved in atherosclerosis, beyond the regulation of circulating LDL cholesterol levels.

PCSK9 levels do not predict severity and recurrence of cardiovascular events in patients with acute myocardial infarction

BACKGROUND AND AIMS

It remains unclear whether serum PCSK9 levels can predict the severity of the disease and the risk of future events in patients with coronary artery disease (CAD). We aimed to evaluate the association between PCSK9 levels, metabolic parameters, severity of CAD on coronary angiography (SYNTAX score), and the risk of in-hospital events and at one-year follow-up.

METHODS AND RESULTS

From September 2015 to December 2016, serum PCSK9 levels were measured on admission in patients not previously receiving statin therapy, and admitted for an acute myocardial infarction (MI), in an intensive care unit from a university hospital. In a total of 648 patients (mean age: 66 years, 67% male), median PCSK9 was 263 ng/ml, higher for females compared with males (270 vs 256 ng/ml, p = 0.009). Serum PCSK9 was associated with LDL cholesterol (r = 0.083, p = 0.036), total cholesterol (r = 0.136, p = 0.001) and triglycerides (r = 0.137, p = 0.001). A positive association was also observed in the subgroup of patients with CRP >10 mg/L (p < 0.001), but not with NT-proBNP, troponin and creatine kinase. PCSK9 levels were similar whatever the SYNTAX score or the number of significant coronary lesions. PCSK9 levels were not associated with in-hospital events (death, recurrent MI and stroke) and events (cardiovascular death, cardiovascular events, recurrent MI) at one-year follow-up.

CONCLUSIONS

In this large cohort of patients hospitalized for acute MI and not previously receiving statin therapy, PCSK9 levels was not associated with the severity or the recurrence of cardiovascular events. The clinical utility of measuring PCSK9 levels for this category of patients therefore appears limited.

New Insights Into the Regulation of Lipoprotein Metabolism by PCSK9: Lessons From Stable Isotope Tracer Studies in Human Subjects

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a convertase enzyme mostly produced by the liver. It is a key regulator of LDL metabolism because of its ability to enhance degradation of the LDL receptor. PCSK9 also regulates the metabolism of lipoprotein(a) [Lp(a)] and triglyceride-rich lipoproteins (TRLs). Its key role in modulating atherosclerotic cardiovascular disease (ASCVD) is supported by genetic studies and clinical outcome trials. Kinetic studies provide mechanistic insight into the role of PCSK9 in regulating the physiology and pathophysiology of plasma lipids and lipoproteins. Kinetic data have demonstrated that plasma PCSK9 concentration is inversely associated with the clearance of LDL in men. Gain-of-function mutations of PCSK9 markedly increase plasma LDL-cholesterol concentrations due to impaired LDL-apoB catabolism. Conversely, PCSK9 deficiency results in low LDL-cholesterol associated with enhanced LDL-apoB clearance. Inhibition of PCSK9 with monoclonal antibodies (such as evolocumab or alirocumab) lowers plasma LDL-cholesterol and apoB levels chiefly by upregulating the catabolism of LDL particles in healthy individuals. As monotherapy, PCSK9 inhibitor reduced Lp(a) concentrations by decreasing the production rate. However, as combination therapy, it reduced the plasma concentration of Lp(a) by increasing the fractional catabolism of Lp(a) particles. In statin-treated patients with high Lp(a), PCSK9 inhibition lowers plasma Lp(a) concentrations by accelerating the catabolism of Lp(a) particles. The effect of PCSK9 inhibition on TRL metabolism has been studied in healthy individuals and in patients with type 2 diabetes. These findings suggest that PCSK9 appears to play a less important role in TRL than LDL metabolism. Kinetic studies of PCSK9 inhibition therapy on lipoprotein metabolism in diverse high risk patient populations (such as familial hypercholesterolemia) and new therapeutic combination also merit further investigation.

Molecular and Cellular Mechanisms of Electronegative Lipoproteins in Cardiovascular Diseases

Dysregulation of glucose and lipid metabolism increases plasma levels of lipoproteins and triglycerides, resulting in vascular endothelial damage. Remarkably, the oxidation of lipid and lipoprotein particles generates electronegative lipoproteins that mediate cellular deterioration of atherosclerosis. In this review, we examined the core of atherosclerotic plaque, which is enriched by byproducts of lipid metabolism and lipoproteins, such as oxidized low-density lipoproteins (oxLDL) and electronegative subfraction of LDL (LDL(−)). We also summarized the chemical properties, receptors, and molecular mechanisms of LDL(−). In combination with other well-known markers of inflammation, namely metabolic diseases, we concluded that LDL(−) can be used as a novel prognostic tool for these lipid disorders. In addition, through understanding the underlying pathophysiological molecular routes for endothelial dysfunction and inflammation, we may reassess current therapeutics and might gain a new direction to treat atherosclerotic cardiovascular diseases, mainly targeting LDL(−) clearance.

Elevated levels of serum PCSK9 in male patients with symptomatic peripheral artery disease: The CAVASIC study

BACKGROUND AND AIMS

Peripheral artery disease (PAD) affects more than 200 million people worldwide. Increased low-density lipoprotein cholesterol (LDL-C)levels are a risk factor for PAD and the concentrations are influenced by proprotein convertase subtilisin/kexin type 9 (PCSK9). PCSK9 regulates the recycling of the LDL receptors to the cell membrane surface. Only a limited number of mostly small studies investigated the association between serum PCSK9 concentrations and PAD of different definition, which revealed contrasting results.

METHODS

Serum PCSK9, lipoprotein(a) [Lp(a)] and other lipoprotein concentrations were measured in male participants of the CAVASIC study, a case-control study of 248 patients with intermittent claudication and 251 age and diabetes-matched controls.

RESULTS

PAD patients had significantly higher PCSK9 concentrations when compared to controls (250 ± 77 vs. 222 ± 68 ng/mL, p < 0.001). Logistic regression analysis with adjustment for age revealed that an increase in PCSK9 concentrations of 100 ng/mL was associated with a 1.78-fold higher risk for PAD (95%CI 1.38-2.33, p = 1.43 × 10^-5). The association attenuated, but was still significant when adjusting additionally for age, Lp(a)-corrected LDL cholesterol, HDL cholesterol, high-sensitivity-CRP, statin treatment, hypertension, diabetes mellitus and smoking (OR = 1.49, 95%CI 1.03-2.18, p = 0.035). The strongest association was observed when both PCSK9 concentrations were above the median and Lp(a) concentrations were above 30 mg/dL (OR = 3.35, 95%CI 1.49-7.71, p = 0.0038).

CONCLUSIONS

Our findings suggest an association of higher PCSK9 concentrations with PAD, which was independent of other lipid parameters and classical cardiovascular risk factors.

Dyslipidaemias and Cardiovascular Disease: Focus on the Role of PCSK9 Inhibitors

Genetic, experimental and clinical studies have consistently confirmed that inhibition of Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) can result in significant lowering of LDL-C and two fully human PCSK9 monoclonal antibodies have received regulatory approval for use in highrisk patients. Co-administration of PCSK9 with statins has resulted in extremely low LDL-C levels with excellent short-term safety profiles. While results from Phase III clinical trials provided significant evidence about the role of PCSK9 inhibitors in reducing cardiovascular event rates, their impact on mortality remains less clear. PCSK9 inhibitor therapy can be considered for high-risk patients who are likely to experience significant cardiovascular risk reduction.

Correlates of Coronary Artery Calcification Prevalence and Severity in Patients With Heterozygous Familial Hypercholesterolemia

Background

Determinants of coronary artery calcification (CAC) prevalence and severity in heterozygous familial hypercholesterolemia (HeFH) remain understudied. The objective of this cross-sectional study was to investigate correlates of CAC in patients with HeFH.

Methods

A CAC score was calculated by a noncontrast computed tomography scan in women (n = 68) and men (n = 78) with genetically defined HeFH. We classified CAC prevalence and severity using 3 categories: CAC score = 0 Agatston Unit (AU), CAC score = 1-100 AU, and CAC score > 100 AU. Information on potential correlates of CAC including familial and personal health history, cardiovascular risk factors, lipid-lowering medication, and lifestyle habits was collected.

Results

A total of 95 patients had prevalent CAC. Independent correlates of CAC prevalence and severity included age (odds ratio [OR] per 10 years: 5.06, 95% confidence interval [CI]: 3.19, 7.93, P < 0.0001), family history of premature cardiovascular disease (OR: 3.88, 95% CI: 1.71, 8.81, P = 0.001), male sex (OR: 3.40, 95% CI: 1.49, 7.78, P = 0.004), statin use (OR: 15.5, 95% CI: 1.89, 126, P = 0.01), diet quality assessed with the Alternative Healthy Eating Index score (OR per 1 standard deviation: 0.59, 95% CI: 0.39, 0.90, P = 0.01), ever smoking (OR: 3.06, 95% CI: 1.20, 7.81, P = 0.02), receptor-negative genotype (OR: 3.17, 95% CI: 1.16, 8.66, P = 0.02), lipoprotein(a) year-score (OR per 1 standard deviation of log-transformed year-score: 1.53, 95% CI: 0.99, 2.36, P = 0.05).

Conclusions

In individuals with HeFH, age, family history of premature cardiovascular disease, sex, statin use, diet quality, smoking status, the LDLR genotype, and lipoprotein(a) concentrations were independently associated with CAC prevalence and severity.

Physiology and role of PCSK9 in vascular disease: Potential impact of localized PCSK9 in vascular wall

Proprotein convertase subtilisin/kexin type-9 (PCSK9), a member of the proprotein convertase family, is an important drug target because of its crucial role in lipid metabolism. Emerging evidence suggests a direct role of localized PCSK9 in the pathogenesis of vascular diseases. With this in our consideration, we reviewed PCSK9 physiology with respect to recent development and major studies (clinical and experimental) on PCSK9 functionality in vascular disease. PCSK9 upregulates low-density lipoprotein (LDL)-cholesterol levels by binding to the LDL-receptor (LDLR) and facilitating its lysosomal degradation. PCSK9 gain-of-function mutations have been confirmed as a novel genetic mechanism for familial hypercholesterolemia. Elevated serum PCSK9 levels in patients with vascular diseases may contribute to coronary artery disease, atherosclerosis, cerebrovascular diseases, vasculitis, aortic diseases, and arterial aging pathogenesis. Experimental models of atherosclerosis, arterial aneurysm, and coronary or carotid artery ligation also support PCSK9 contribution to inflammatory response and disease progression, through LDLR-dependent or -independent mechanisms. More recently, several clinical trials have confirmed that anti-PCSK9 monoclonal antibodies can reduce systemic LDL levels, total nonfatal cardiovascular events, and all-cause mortality. Interaction of PCSK9 with other receptor proteins (LDLR-related proteins, cluster of differentiation family members, epithelial Na⁺ channels, and sortilin) may underlie its roles in vascular disease. Improved understanding of PCSK9 roles and molecular mechanisms in various vascular diseases will facilitate advances in lipid-lowering therapy and disease prevention.

Arylesterase activity but not PCSK9 levels is associated with chronic kidney disease in type 2 diabetes

PURPOSE

Oxidative stress and dyslipidemia have been found to be associated with the progression of chronic kidney disease (CKD) in type 2 diabetes mellitus (T2DM) patients. Paraoxonase 1 (PON-1) activity, and proprotein convertase subtilisin kexin type 9 (PCSK9) levels play an important role regarding anti-oxidants, and lipid metabolism, respectively. The aim of this study was to investigate the association of PON-1 activity, and PCSK9 levels with CKD in T2DM.

METHODS

A total of 180 T2DM (87 CKD, and 93 non-CKD) with age-, and gender-matched subjects were recruited in this study. PON-1 activity was measured with two kinds of substrate: paraoxon for paraoxonase (PONase) activity and phenylacetate for arylesterase (AREase) activity. PCSK9 levels were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

AREase activity was significantly lower in CKD compared with non-CKD (225.53 ± 108.73 vs. 257.45 ± 106.12 kU/L, p = 0.044) in T2DM, whereas there was no significant difference in PONase activity and PCSK9 levels between CKD and non-CKD groups. In addition, multivariate logistic regression analysis showed that the lowest tertile of AREase increased the risk for CKD in T2DM (OR 3.251; 95% CI 1.333-7.926, p = 0.010), whereas PONase activity and PCSK9 levels were not associated with CKD in T2DM.

CONCLUSION

Reduced AREase activity can increase the risk for CKD in T2DM patients. AREase activity, but not PONase activity and PCSK9 levels, may be used as the biomarker for predicting the progression of CKD in T2DM.

Association between lipoprotein(a) (Lp(a)) levels and Lp(a) genetic variants with coronary artery calcification

Background

To examine the association between lipoprotein(a) (Lp(a)) levels, LPA (rs10455872 and rs3798220) and IL1F9 (rs13415097) single nucleotide polymorphisms (SNPs) with coronary artery calcification (CAC), an important predictor for coronary artery disease (CAD).

Methods

We used data from 3799 (mean age ± SD: 59.0 ± 7.7 years, 47.1% men) Heinz Nixdorf Recall study participants. We applied linear regression models to explore the relation between the log-transformed Lp(a) levels and LPA and IL1F9 SNPs with log_e (CAC + 1). The association between the SNPs and log-transformed Lp(a) levels was further assessed using linear regression. The models were adjusted for age and sex (Model 1) and additionally for Lp(a) levels (Model 2).

Results

We observed a statistically significant association between log-transformed Lp(a) levels and CAC (Model 1: beta per log-unit increase in Lp(a) levels = 0.11; 95% confidence interval [95% CI] [0.04; 0.18], p = 0.002). Furthermore, the LPA SNP rs10455872 showed a statistically significant association with CAC (Model 1: beta per allele = 0.37 [0.14; 0.61], p = 0.002). The association between rs10455872 and CAC was attenuated after adjustment for Lp(a) levels (Model 2: beta per allele = 0.26 [− 0.01; 0.53], p = 0.06). Both LPA SNPs also showed a statistically significant association with Lp(a) levels (Model 1: beta_rs10455872 per allele: 1.56 [1.46; 1.65], p < 0.0001 and beta_rs3798220 per allele: 1.51 [1.33; 1.69], p < 0.0001)). The Mendelian randomization analysis showed that Lp(a) is a causal risk factor for CAC (estimate per log-unit increase in Lp(a) levels (95% CI), p: 0.27 [0.11; 0.44], p = 0.001). The IL1F9 SNP did not show any statistically significant association with Lp(a) levels or with CAC.

Conclusions

We provide evidence for the association of LPA rs10455872 with higher levels of Lp(a) and CAC in our study. The results of our study suggest that rs10455872, mediated by Lp(a) levels, might play a role in promoting the development of atherosclerosis leading to cardiovascular disease events.

Circulating PCSK9 Level and Risk of Cardiovascular Events and Death in Hemodialysis Patients

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a promising new target for the prevention of cardiovascular (CV) events. However, the clinical significance of circulating PCSK9 is unclear in hemodialysis (HD) patients. A total of 353 HD patients were prospectively enrolled from June 2016 to August 2019 in a K-cohort. Plasma PCSK9 level was measured at the time of study enrollment. The primary endpoint was defined as a composite of CV event and death. Plasma PCSK9 level was positively correlated with total cholesterol level in patients with statin treatment. Multivariate linear regression analysis revealed that baseline serum glucose, albumin, total cholesterol, and statin treatment were independent determinants of circulating PCSK9 levels. Cumulative rates of composite and CV events were significantly higher in patients with tertile 3 PCSK9 (p = 0.017 and p = 0.010, respectively). In multivariate Cox-regression analysis, PCSK9 tertile 3 was associated with a 1.97-fold risk of composite events (95% CI, 1.13–3.45), and it was associated with a 2.31-fold risk of CV events (95% CI, 1.17–4.59). In conclusion, a higher circulating PCSK9 level was independently associated with incident CV events and death in HD patients. These results suggest the importance of future studies regarding the effect of PCSK9 inhibition.

Circulating PCSK9 and cardiovascular events in FH patients with standard lipid-lowering therapy

BACKGROUND

Proprotein convertase subtilisin/kexin 9 (PCSK9) has been proposed as a novel target for coronary artery disease (CAD). Familial hypercholesterolemia (FH) is characterized by high prevalence of CAD and major cardiovascular events (MACEs). However, no data is available on the association between PCSK9 levels and MACEs in FH patients with standard lipid lowering therapy.

METHODS

A total of 338 consecutive heterozygous FH (Dutch Lipid Clinic Network score ≥ 6) was enrolled and followed up for the occurrence of MACEs. Multidetector CT and coronary angiography were performed to determine coronary artery calcification score (CACS) and Gensini score (GS). Multivariable Cox regression analyses were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs). Plasma PCSK9 concentrations were determined by enzyme immunoassay.

RESULTS

PCSK9 was independently and positively associated CACS and GS at baseline. During a mean follow-up of 3 years, 33 (9.8%) events occurred. Patients with MACEs had higher median PCSK9 compared with those without (332.47 vs. 311.89 ng/mL, p = 0.038). Kaplan-Meier analysis revealed that patients with higher PCSK9 presented lower event-free survival (p = 0.0017). PCSK9 was statistically correlated with MACEs after adjusting for confounding factors, with the HR per SD being 1.86 (1.31-2.65) and 3.70 (1.16-11.82) for the highest tertile compared with the lowest tertile. Adding PCSK9 to Cox prediction model led to a statistical improvement in net reclassification and integrated discrimination.

CONCLUSION

Elevated levels of PCSK9 were positively associated with the development of CAD and future cardiovascular events, suggesting that measurement of PCSK9 concentration might be useful for cardiovascular risk stratification. Further studies are needed to confirm our results.

Apolipoprotein(a) phenotype determines the correlations of lipoprotein(a) and proprotein convertase subtilisin/kexin type 9 levels in patients with potential familial hypercholesterolemia

BACKGROUND AND AIMS

The aim of this study is to investigate the relation between lipoprotein(a) [Lp(a)] and proprotein convertase subtilisin/kexin type 9 (PCSK9) concentrations, and their complex, in patients with potential familial hypercholesterolemia (FH), depending on apo(a) phenotype.

METHODS

The study included 205 patients with total cholesterol (TC) > 7.5 mmol/L and/or low density lipoprotein cholesterol (LDL-C)>4.9 mmol/L, 32 (15%) patients suffered from ischemic heart disease (IHD), 64 were taking statins. The diagnosis of FH was estimated according to the Dutch Lipid Clinics Network criteria. Lipid parameters, apoB-containing lipoprotein subfractions, Lp(a), PCSK9, Lp(a)-PCSK9 complex levels and apo(a) phenotype were determined. Depending on the apo(a) phenotype, all patients were divided into 2 groups: with high molecular weight (HMW) (n = 145) and low molecular weight (LMW) (n = 60) apo(a) phenotype.

RESULTS

The groups were comparable by all major clinical characteristics and biochemical parameters. In the whole group, PCSK9 concentration correlated with age, statins intake, Lp(a), TC and TG levels. Correlation between Lp(a) and PCSK9 levels was found only in the LMW apo(a) phenotype group independently of statins intake (r = 0.46, p < 0.001). Associations between Lp(a)-PCSK9 complex and large subfractions of intermediate (r = 0.30) and low-density lipoproteins (r = 0.30, p < 0.05 for both) were observed, with more significance in group 2 (r = 0.59, p < 0.005 and r = 0.40, p < 0.05, respectively).

CONCLUSIONS

In patients with potential familial hypercholesterolemia, positive correlations between concentrations of Lp(a) and PCSK9, as well as of Lp(a)-PCSK9 plasma complex with large subfractions of intermediate and low-density lipoproteins (IDL-1 and LDL-C), were determined by the LMW apo(a) phenotype.

Association of PCSK9 plasma levels with metabolic patterns and coronary atherosclerosis in patients with stable angina

OBJECTIVE

Aim of this study was to evaluate the relationship of plasma PCSK9 with metabolic and inflammatory profile and coronary atherosclerotic burden in patients with suspected CAD enrolled in the EVINCI study.

METHODS

PCSK9 was measured in 539 patients (60.3 ± 8.6 years, 256 males) with symptoms of CAD characterized by risk factors, bio-humoral profiles, and treatment. N = 412 patients underwent coronary computed tomography angiography (CTA) to assess the presence and characteristics of coronary atherosclerosis. A CTA score, combining extent, severity, composition, and location of plaques was computed.

RESULTS

Patients were divided according to PCSK9 quartiles: I (< 136 ng/mL), II-III (136-266 ng/mL), and IV quartile (> 266 ng/mL). Compared with patients in quartile IV, patients in quartile I had a higher prevalence of the metabolic syndrome and higher values of body mass index. LDL- and HDL-cholesterol were significantly lower in patients in the quartile I than in those in quartile IV. Coronary CTA documented normal vessels in 30% and obstructive CAD in 35% of cases without differences among PCSK9 quartiles. Compared with patients with the highest levels, patients with the lowest PCSK9 levels had a higher CTA score mainly due to higher number of mixed non-obstructive coronary plaques. At multivariable analysis including clinical, medications, and lipid variables, PCSK9 was an independent predictor of the CTA score (coefficient - 0.129, SE 0.03, P < 0.0001), together with age, male gender, statins, interleukin-6, and leptin.

CONCLUSION

In patients with stable CAD, low PCSK9 plasma levels are associated with a particular metabolic phenotype (low HDL cholesterol, the metabolic syndrome, obesity, insulin resistance and diabetes) and diffuse non-obstructive coronary atherosclerosis. Trial registration ClinicalTrials.gov NCT00979199. Registered September 17, 2009.

Plasma proprotein convertase subtilisin/kexin type 9 concentration and recurrent cardiovascular events in patients with familial hypercholesterolemia

AIMS

Familial hypercholesterolemia patients are characterized by early onset of coronary artery calcification and atherosclerosis, and high incidence of cardiovascular events. Plasma proprotein convertase subtilisin/kexin type 9 was reported to be a predictor for cardiovascular risk in the general population. However, its prognostic value for predicting recurrent cardiovascular events in familial hypercholesterolemia patients remains undetermined.

METHODS

A total of 249 patients with molecularly and/or clinically (Dutch Lipid Clinic Network score > 6) defined familial hypercholesterolemia who had experienced a first cardiovascular event were consecutively included and plasma proprotein convertase subtilisin/kexin type 9 concentrations were measured by enzyme-linked immunosorbent assay. Coronary artery calcification was measured using Agatston method and coronary severity was assessed by Gensini score, respectively. All patients received standard lipid-lowering therapy and were followed-up for recurrent cardiovascular events. Univariate and multivariate regression and Cox analyses was used to calculate hazard ratios with 95% confidence interval.

RESULTS

Circulating proprotein convertase subtilisin/kexin type 9 concentrations were positively associated with coronary artery calcification scores and Gensini score by both univariate and multivariate analyses. During a mean follow-up of 43 ± 19 months, 29 (11.51%) recurrent cardiovascular events occurred. Kaplan-Meier analysis showed that patients with the highest proprotein convertase subtilisin/kexin type 9 levels had the lowest event-free survival time. Multivariable Cox regression analysis revealed that proprotein convertase subtilisin/kexin type 9 was independently associated with recurrent cardiovascular events (hazard ratio: 1.45, 95% confidence interval: 1.11-1.88). The combination of proprotein convertase subtilisin/kexin type 9 to Cox prediction model led to an enhanced predictive value for recurrent cardiovascular events.

CONCLUSIONS

Increased level of proprotein convertase subtilisin/kexin type 9 was a significant risk factor of atherosclerosis and independently predicted future recurrent cardiovascular events in familial hypercholesterolemia patients receiving standard lipid-lowering treatment.

PCSK9 and atherosclerosis burden in the coronary arteries of patients undergoing coronary angiography

AIMS

To investigate the association between plasma proprotein convertase subtilisin/kexin type 9 (PCSK9) concentrations, current acute coronary syndrome (ACS), coronary artery disease (CAD) presence, severity and extension and the burden of coronary calcifications in patients with suspected CAD.

METHODS AND RESULTS

One hundred and one patients, with or without current ACS, were recruited for this cross-sectional study. CAD presence was defined based on either the presence or absence of at least one significant (≥50%) CAD lesion (SCAD). CAD severity was classified according to the absence of coronary lesions, the presence of non-significant (<50%) CAD (MCAD) or SCAD in at least one major coronary artery. Patients with one, two or three significantly diseased major coronary arteries were defined as 1-SCAD, 2-SCAD and 3-SCAD, respectively. The cumulative length of SCAD lesions and the amount of calcifications in coronary arteries were estimated. Plasma PCSK9 concentrations were higher in patients with SCAD as compared to those without (p = .012). A significant increase in plasma PCSK9 concentrations was observed with greater CAD severity (p = .042). Higher plasma PCSK9 concentrations were found in 3-SCAD patients as compared to either 2-SCAD or 1-SCAD (p < .001). PCSK9 increased with the cumulative length of SCAD lesions and the burden of calcifications (p < .05 for both comparisons). Multivariable adjustment abolished the association between PCSK9 and either CAD presence or severity, but not the association between PCSK9 and the number of significantly diseased vessels, SCAD lesion length and the burden of coronary calcifications. ACS was associated with a borderline significant increase of plasma PCSK9 concentrations among patients not taking statins (p = .05).

CONCLUSION

Circulating PCSK9 concentrations discriminate patients with greater coronary atherosclerotic lesion extension and calcification, and are increased in patients with current ACS.

To test, or not to test: that is the question for the future of lipoprotein(a)

INTRODUCTION

Lipoprotein(a) [Lp(a)] is a potent, highly heritable and common risk factor for atherosclerotic cardiovascular disease (ASCVD). Evidence for a causal association between elevated Lp(a) and ASCVD has been provided by large epidemiological investigations that have demonstrated a curvilinear association with increased risk, as well as from genetic examinations and cellular and transgenic animal studies. Although there are several therapies available for lowering Lp(a), none are selective for Lp(a) and there is no clinical trial data that has specifically shown that lowering Lp(a) reduces the risk of ASCVD. Hence, screening for elevated Lp(a) is not routinely incorporated into clinical practice. Areas covered: This paper reviews the current evidence supporting the causal role of Lp(a) in the primary and secondary prevention of ASCVD, screening approaches for high Lp(a), current guidelines on testing Lp(a), and barriers to the routine screening of elevated Lp(a) in clinical practice. Expert opinion: At present, there is a moderate level of evidence supporting the routine screening of elevated Lp(a). Current guidelines recommend testing for elevated Lp(a) in individuals at intermediate or high risk of ASCVD.

Race-Based Differences in Lipoprotein(a)-Associated Risk of Carotid Atherosclerosis

Objective- Lp(a) [lipoprotein(a)] is a well-described risk factor for atherosclerosis, but Lp(a)-associated risk may vary by race/ethnicity. We aimed to determine whether race/ethnicity modifies Lp(a)-related risk of carotid atherosclerotic plaque outcomes among black, white, Chinese, and Hispanic individuals. Approach and Results- Carotid plaque presence and score were assessed by ultrasonography at baseline (n=5155) and following a median 9.4 year period (n=3380) in MESA (Multi-Ethnic Study of Atherosclerosis) participants. Lp(a) concentrations were measured by immunoassay and examined as a continuous and categorical variable using clinically-based cutoffs, 30 and 50 mg/dL. Lp(a) was related to greater risk of prevalent carotid plaque at baseline in whites alone (all P<0.001): per log unit (relative risk, 1.05); Lp(a)≥30 mg/dL (relative risk, 1.16); and Lp(a)≥50 mg/dL (relative risk, 1.20). Lp(a) levels over 50 mg/dL were associated with a higher plaque score at baseline in whites (all P<0.001) and Hispanics ( P=0.04). In prospective analyses, whites with Lp(a) ≥50 mg/dL were found to have greater risk of plaque progression (relative risk, 1.12; P=0.03) and higher plaque scores (all P<0.001) over the 9.4-year follow-up. Race-based differences between whites and black participants were significant for cross-sectional associations and for carotid plaque score following the 9.4 year study period. Conclusions- Race was found to be a modifying variable in Lp(a)-related risk of carotid plaque, and Lp(a) levels may have greater influence on plaque burden in whites than in black individuals. Borderline results in Hispanics suggest that elevated Lp(a) may increase the risk of carotid plaque, but follow-up studies are needed.

Clinical, behavioral and biomarker predictors of PCSK9 levels in HIV-infected patients naïve of statin therapy: A cross-sectional analysis from the Swiss HIV cohort

BACKGROUND AND AIMS

Better characterization of Proprotein Convertase Subtilisin/Kexin 9 (PCSK9) profile is currently needed to tailor appropriate lipid-lowering strategies in HIV patients.

METHODS

HIV-infected individuals aged ≥ 40 years and naive of statin therapy included in the Swiss HIV cohort study were screened for PCSK9 levels with a routine blood sample collection in 2014 at the Geneva University Hospitals. An exploratory linear regression model was built including clinical (age, sex, ethnicity, cardiovascular risk factors, body mass index, low CD4 defined as ≤200 cells/μl, leucocytes, lymphocytes, platelet, antiretroviral therapy), behavioral (tobacco and marijuana smoking, alcohol use and physical activity) and biomarker (CRP, TNF-α, IL-8, Il-10 and MCP-1) to investigate association with continuous PCSK9 levels.

RESULTS

We studied 239 HIV-infected individuals who met inclusion criteria and available PCSK9 levels with a mean age of 49 years. 35 subjects (14.6%) reported marijuana consumption, of whom 20 (57.1%) reported daily consumption and 15 (6.3%) occasional use. PCSK9 levels were correlated with low-density lipoprotein-cholesterol (LDL-C). Our exploratory model identified marijuana consumption (p=0.023) and low CD4 values (p=0.020) as significantly associated factors with higher PCSK9 levels. No association was found with Framingham risk score. Patients with marijuana consumption had significantly higher levels of PCSK9 with a dose-response effect (p < 0.001); the association persisted after adjustment for the calculated Framingham risk score (p=0.003) and additional adjustment for clinical variables (p=0.027).

CONCLUSIONS

In HIV-infected individuals naïve of statin treatment, marijuana consumption and low CD4 values are associated with higher PCSK9 levels independently of clinically relevant confounding factors.

Association between circulating proprotein convertase subtilisin/kexin type 9 levels and prognosis in patients with severe chronic kidney disease

Background

Chronic kidney disease is a risk factor for premature development of coronary atherosclerosis and mortality. A high level of proprotein convertase subtilisin/kexin type 9 (PCSK9) is a recently recognized cardiovascular risk factor and has become the target of effective inhibitory treatment. In 167 kidney transplantation candidates, we aimed to: (i) compare levels of PCSK9 with those of healthy controls, (ii) examine the association between levels of PCSK9 and low-density lipoprotein cholesterol (LDL-c) and the degree of coronary artery disease (CAD) and (iii) evaluate if levels of PCSK9 predict major adverse cardiac events (MACE) and mortality.

Methods

Kidney transplant candidates (n = 167) underwent coronary computed tomography angiography (CCTA) and invasive coronary angiography (ICA) before transplantation. MACE and mortality data were extracted from the Western Denmark Heart Registry, a review of patient records and patient interviews. A group of 79 healthy subjects were used as controls.

Results

Mean PCSK9 levels did not differ between healthy controls and kidney transplant candidates. In patients not receiving lipid-lowering therapy, PCSK9 correlated positively with LDL-c (rho = 0.24, P &lt; 0.05). Mean PCSK9 was similar in patients with and without obstructive CAD at both CCTA and ICA. In a multiple regression analysis, PCSK9 was associated with neither LDL-c (β=−6.45, P = 0.44) nor coronary artery calcium score (β=2.17, P = 0.84). During a follow-up of 3.7 years, PCSK9 levels were not associated with either MACE or mortality.

Conclusions

The ability of PCSK9 levels to predict cardiovascular disease and prognosis does not seem to apply to a cohort of kidney transplant candidates.

Pleiotropic effects of proprotein convertase subtilisin/kexin type 9 inhibitors?

PURPOSE OF REVIEW

Current data suggest that proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors may affect many metabolic pathways beyond lowering LDL cholesterol. The aim of the present manuscript is to present these so-called pleiotropic effects of PCSK9 inhibitors.

RECENT FINDINGS

PCSK9 may affect the activity of other receptors beyond LDL receptors (LDLR), such as cluster of differentiation 36 (CD36), very-low-density-lipoprotein (VLDL) receptors, apolipoprotein (Apo) E receptors, LDLR-related protein 1 (LRP-1) and ATP-Binding Cassette Transporter (ABCA1). Thus, a role of PCSK9 in the development of atherosclerosis, in vascular wall inflammation and in platelet function has been suggested. Additionally, PCSK9 inhibitors may affect lipid variables beyond LDL cholesterol, carbohydrate variables, as well as they may affect brain and kidney function. Additionally, a controversial role of PCSK9 in sepsis, hepatitis C infection and Alzheimer's disease has been suggested.

SUMMARY

These possible pleiotropic effects of PCSK9 inhibitors need further research, as they may affect cardiovascular risk and provide further insights in the development of atherosclerosis and other diseases such as Alzheimer's disease or chronic viral infection and sepsis.

Familial Hypercholesterolemia: New Horizons for Diagnosis and Effective Management

Familial hypercholesterolemia (FH) is a common genetic cause of premature cardiovascular disease (CVD). The reported prevalence rates for both heterozygous FH (HeFH) and homozygous FH (HoFH) vary significantly, and this can be attributed, at least in part, to the variable diagnostic criteria used across different populations. Due to lack of consistent data, new global registries and unified guidelines are being formed, which are expected to advance current knowledge and improve the care of FH patients. This review presents a comprehensive overview of the pathophysiology, epidemiology, manifestations, and pharmacological treatment of FH, whilst summarizing the up-to-date relevant recommendations and guidelines. Ongoing research in FH seems promising and novel therapies are expected to be introduced in clinical practice in order to compliment or even substitute current treatment options, aiming for better lipid-lowering effects, fewer side effects, and improved clinical outcomes.

Association between proprotein convertase subtilisin/kexin type 9 and late saphenous vein graft disease after coronary artery bypass grafting: a cross-sectional study

OBJECTIVE

The study aims to explore the association between serum proprotein convertase subtilisin/kexin type 9 (PCSK9) level and saphenous vein grafts disease (SVGD) after coronary artery bypass grafting (CABG).

DESIGN

A cross-sectional study.

SETTING

A secondary hospital in Tianjin City, China.

PARTICIPANTS

A total of 231 participants were included in the study. Inclusion criteria were as follows: age ≥18 years, previous CABG surgery at least 12 months ago, at least one SVG for bypass during CABG, abnormal non-invasive test results or recurrent stable angina pectoris by coronary angiography indications, and willing to participate and sign informed consent. Participants with any of the following were excluded from the study: congenital valvular disease, decompensated heart failure, anaemia defined as a haemoglobin level of <12 g/dL in women or <13 g/dL in men, malignant neoplasms, renal failure, severe hepatic disease, thyroid disease, acute or chronic inflammatory disease and chronic obstructive lung disease.

PRIMARY OUTCOME MEASURE

SVGD was defined as at least one SVG with significant stenosis (≥50%). Circulating PCSK9 levels were measured using commercial ELISA kits according to the manufacturer's instructions.

RESULTS

The mean PCSK9 level in the SVGD group was significantly higher than that in the patent group (275.2±38.6 vs 249.3±37.7, p<0.01). The multivariate logistic regression model revealed a significant association between serum PCSK9 and SVGD (OR 2.08, 95% CI 1.46-2.95) per 1 SD increase in serum PCSK9.

CONCLUSIONS

The present study is the first to identify an independent association between PCSK9 and late SVGD after adjustment for established cardiovascular risk factors. A multicentre prospective cohort study with large sample size should be conducted in the future to further research this relationship.

PCSK9: From Basic Science Discoveries to Clinical Trials

Unknown 15 years ago, PCSK9 (proprotein convertase subtilisin/kexin type 9) is now common parlance among scientists and clinicians interested in prevention and treatment of atherosclerotic cardiovascular disease. What makes this story so special is not its recent discovery nor the fact that it uncovered previously unknown biology but rather that these important scientific insights have been translated into an effective medical therapy in record time. Indeed, the translation of this discovery to novel therapeutic serves as one of the best examples of how genetic insights can be leveraged into intelligent target drug discovery. The PCSK9 saga is unfolding quickly but is far from complete. Here, we review major scientific understandings as they relate to the role of PCSK9 in lipoprotein metabolism and atherosclerotic cardiovascular disease and the impact that therapies designed to inhibit its action are having in the clinical setting.

Inhibition of Aortic Calcification by Policosanol in Dyslipidemic Rabbits Is Enhanced by Pentoxifylline

Policosanol (POL) is a hypocholesterolemic drug of natural origin and has been shown to reduce circulating levels of proprotein convertase subtilisin/kexin type 9 (PCSK9) in healthy participants. Recently, we have reported that POL can attenuate aortic calcification in diabetic dyslipidemic rats; however, the underlying mechanism is not fully elucidated. We aimed to investigate the effect of POL on aortic calcification and whether PCSK9 has a contributory role and also to examine whether the combination of POL with pentoxifylline (PTX) as anti–tumor necrosis factor α would offer additional benefits. Thirty adult male New Zealand rabbits weighing 1.5 to 2 kg were randomly assigned to 5 groups. One group received standard chow diet and served as normal control group (NC). The other 4 groups received 0.5% wt/wt cholesterol-rich diet for 12 weeks and concurrently treated with placebo, POL, PTX, or a combination of POL and PTX. Sera samples and aortic tissue were collected for biochemical measurements and histological assessment. Rabbits fed a cholesterol-rich diet demonstrated dyslipidemia, increased inflammatory state, and elevated serum levels of PCSK9, compared to the NC group. Aortic calcification was evident in dyslipidemic rabbits, represented by increased calcium deposition and osteopontin expression in aortic tissue, along with elevated serum levels of alkaline phosphatase and osteocalcin. Dyslipidemic rabbits showed a significant upregulation of wingless-type MMTV integration site family 3A and bone morphogenetic protein 2 genes in their aortic tissue. Policosanol significantly reduced circulating PCSK9 levels, suppressed calcification markers, and attenuated aortic calcification. Combination of POL with PTX alleviated aortic calcification to a greater extent than either monotherapy, which may be attributed to further suppression of PCSK9 and calcification markers. These findings suggested that POL exerted anticalcifying effect partly via inhibition of PCSK9. Combination of POL and PTX offered additional benefits and might represent a promising therapeutic option for aortic calcification.

Lipoprotein(a) level associates with coronary artery disease rather than carotid lesions in patients with familial hypercholesterolemia

BACKGROUND

Lipoprotein(a) [Lp(a)] level is a novel risk factor for atherosclerotic cardiovascular disease in patients with familial hypercholesterolemia (FH), while its impact on the different sites of arteries remains undetermined. We aim to examine the associations of Lp(a) levels with coronary and carotid atherosclerosis in patients with heterozygous FH (HeFH).

METHODS

A total of 148 patients with HeFH who have received carotid ultrasonography and coronary angiography due to chest pain were enrolled. Plasma Lp(a) was measured using immunoturbidimetric method. Finally, the associations between Lp(a) and coronary as well as carotid lesions were evaluated.

RESULTS

Patients with Lp(a) ≥ 300 mg/L had similar carotid intima-media thickness (IMT, 0.782 ± 0.16 mm vs 0.798 ± 0.18 mm, P = .579) and plaque prevalence (66.7% vs 65%, P = .833) compared to those with Lp(a) < 300 mg/L, but had a higher prevalence of coronary artery disease (CAD, 69.7% vs 50.0%, P = .016) and higher Gensini score (GS, median 27 vs 3, P = .006). Moreover, no correlations were found between carotid mean IMT with either Lp(a) level or Lp(a) year score, while positive relation of Lp(a) with GS did. Multivariate regression analysis revealed that Lp(a), Lp(a) year score, and Lp(a) ≥ 300 g/L were all independent predictors for the presence of CAD (OR = 4.99, P = .007; OR = 4.73, P = .009; OR = 4.46, P = .006, respectively) but not for carotid plaques.

CONCLUSIONS

This study suggested that Lp(a) level was associated with the presence and severity of CAD but not with carotid atherosclerosis in patients with HeFH.

Elevated lipoprotein(a) and familial hypercholesterolemia in the coronary care unit: Between Scylla and Charybdis

BACKGROUND

Elevated lipoprotein(a) (Lp[a]) and familial hypercholesterolemia (FH) are inherited lipid disorders. Their frequencies, coexistence, and associations with premature coronary artery disease (CAD) in patients admitted to the coronary care unit (CCU) remain to be defined.

HYPOTHESIS

Elevated Lp(a) and FH are commonly encountered among CCU patients and independently associated with increased premature CAD risk.

METHODS

Plasma Lp(a) concentrations were measured in consecutive patients admitted to the CCU with an acute coronary syndrome (ACS) or prior history of CAD for 6.5 months. Elevated Lp(a) was defined as concentrations ≥0.5 g/L. Patients with LDL-C ≥ 5 mmol/L exhibited phenotypic FH. Premature CAD was diagnosed in those age < 60 years, and the relationship between this and elevated Lp(a) and FH was determined by logistic regression.

RESULTS

316 patients were screened; 163 (51.6%) had premature CAD. Overall, elevated Lp(a) and FH were identified in 27.0% and 11.6% of patients, respectively. Both disorders were detected in 4.4% of individuals. Elevated Lp(a) (32.0% vs 22.2%; P = 0.019) and FH phenotype (15.5% vs 8.0%; P = 0.052) were more common with premature vs nonpremature CAD. Elevated Lp(a) alone conferred a 1.9-fold, FH alone a 3.2-fold, and the combination a 5.3-fold increased risk of premature CAD (P = 0.005).

CONCLUSIONS

Elevated Lp(a) and phenotypic FH were commonly encountered and more frequent with premature CAD. The combination of both disorders is especially associated with increased CAD risk. Patients admitted to the CCU with ACS or previously documented CAD should be routinely screened for elevated Lp(a) and FH.

PCSK9 and Atherosclerosis - Lipids and Beyond

Even though it is only a little over a decade from the discovery of proprotein convertase subtilisin/kexin type 9 (PCSK9) as a plasma protein that associates with both high and low cholesterol syndromes, a rich body of knowledge has developed, and drugs inhibiting this target have been approved in many markets. While the majority of research in recent years has focused on the impact of therapeutic antagonism of this molecule, important lines of investigation have emerged characterizing its unique physiology as it relates to cholesterol metabolism and atherosclerosis. The PCSK9 story is unfolding rapidly but is far from complete. One chapter that is of particular interest is the possible direct link between PCSK9 and atherosclerosis. This review specifically examines this relationship drawing from data produced from experimental models of plaque biology and inflammation, atherosclerosis imaging studies, and observational epidemiology.