The role of lipoprotein(a) in the formation of arterial plaques, stenoses and occlusions

Familial hypercholesterolemia and elevated lipoprotein(a): double heritable risk and new therapeutic opportunities

There is compelling evidence that the elevated plasma lipoprotein(a) [Lp(a)] levels increase the risk of atherosclerotic cardiovascular disease (ASCVD) in the general population. Like low-density lipoprotein (LDL) particles, Lp(a) particles contain cholesterol and promote atherosclerosis. In addition, Lp(a) particles contain strongly proinflammatory oxidized phospholipids and a unique apoprotein, apo(a), which promotes the growth of an arterial thrombus. At least one in 250 individuals worldwide suffer from the heterozygous form of familial hypercholesterolemia (HeFH), a condition in which LDL-cholesterol (LDL-C) is significantly elevated since birth. FH-causing mutations in the LDL receptor gene demonstrate a clear gene-dosage effect on Lp(a) plasma concentrations and elevated Lp(a) levels are present in 30-50% of patients with HeFH. The cumulative burden of two genetically determined pro-atherogenic lipoproteins, LDL and Lp(a), is a potent driver of ASCVD in HeFH patients. Statins are the cornerstone of treatment of HeFH, but they do not lower the plasma concentrations of Lp(a). Emerging therapies effectively lower Lp(a) by as much as 90% using RNA-based approaches that target the transcriptional product of the LPA gene. We are now approaching the dawn of an era, in which permanent and significant lowering of the high cholesterol burden of HeFH patients can be achieved. If outcome trials of novel Lp(a)-lowering therapies prove to be safe and cost-effective, they will provide additional risk reduction needed to effectively treat HeFH and potentially lower the CVD risk in these high-risk patients even more than currently achieved with LDL-C lowering alone.

What We Have Learned from the Recent Meta-analyses on Diagnostic Methods for Atherosclerotic Plaque Regression

PURPOSE OF REVIEW

Atherosclerosis has major morbidity and mortality implications globally. While it has often been considered an irreversible degenerative process, recent evidence provides compelling proof that atherosclerosis can be reversed. Plaque regression is however difficult to appraise and quantify, with competing diagnostic methods available. Given the potential of evidence synthesis to provide clinical guidance, we aimed to review recent meta-analyses on diagnostic methods for atherosclerotic plaque regression.

RECENT FINDINGS

We identified 8 meta-analyses published between 2015 and 2017, including 79 studies and 14,442 patients, followed for a median of 12 months. They reported on atherosclerotic plaque regression appraised with carotid duplex ultrasound, coronary computed tomography, carotid magnetic resonance, coronary intravascular ultrasound, and coronary optical coherence tomography. Overall, all meta-analyses showed significant atherosclerotic plaque regression with lipid-lowering therapy, with the most notable effects on echogenicity, lipid-rich necrotic core volume, wall/plaque volume, dense calcium volume, and fibrous cap thickness. Significant interactions were found with concomitant changes in low density lipoprotein cholesterol, high density lipoprotein cholesterol, and C-reactive protein levels, and with ethnicity. Atherosclerotic plaque regression and conversion to a stable phenotype is possible with intensive medical therapy and can be demonstrated in patients using a variety of non-invasive and invasive imaging modalities.

Elevated Lipoprotein (a) and Risk of Poor Functional Outcome in Chinese Patients with Ischemic Stroke and Type 2 Diabetes

The aim of this study was to evaluate the short-term prognostic value of early measurement of serum lipoprotein (a) [Lp(a)] levels in Chinese patients with type 2 diabetes (T2D) and acute ischemic stroke (AIS). The study population comprised 232 consecutive patients with an AIS diagnosis complicated with T2D. Functional outcome was obtained on month 3 according to the modified Rankin Scale (mRS). Unfavorable functional outcome was defined as a mRS score of 3 to 6 points. The prognostic value of Lp(a) at admission to predict the unfavorable functional outcome 3 months after stroke onset was compared with the National Institutes of Health Stroke Scale score and other known outcome predictors. The Lp(a) levels in those patients were obtained with a median value of 16.8 mg/dl (IQR, 9.5-34.4 mg/dl). At 3-month follow-up, an unfavorable functional outcome was found in 86 patients (37.1%). In multivariate models comparing the second (Q2), third, and fourth quartiles against the first quartile of Lp(a), concentrations of Lp(a) in Q2, Q3, and Q4 were associated with unfavorable outcome, and increased risk of unfavorable outcome by 42, 131, and 211%. Interestingly, an elevated Lp(a, > 30 mg/dl) was also associated with unfavorable outcome, and with adjusted OR of 2.25 (95% CI 1.39-3.68). The AUC was significantly increased by adding Lp(a) to established risk factors (difference, 0.041 [95% CI, 0.034-0.053]; P = 0.02). The addition of Lp(a) to established risk factors significantly improved net reclassification improvement and integrated discrimination improvement. Higher Lp(a) levels at admission were associated with increased risk of unfavorable functional outcome and might be useful in identifying stroke patients with T2D at risk for unfavorable functional outcome for early prevention strategies.

Total cholesterol content of erythrocyte membranes is associated with the severity of coronary artery disease and the therapeutic effect of rosuvastatin

INTRODUCTION

Numerous studies suggest that total cholesterol content of erythrocyte membranes (CEM) might play a critical role in atherosclerotic plaque progression and instability. However, the exact role of CEM in atherosclerosis remains obscure. Our study was designed to investigate the association between CEM and the severity of coronary artery disease (CAD), and to assess the effect of rosuvastatin on CEM levels.

METHODS

CEM levels were assessed in 136 participants, including acute coronary syndrome (ACS) (non-ST-segment elevation ACS (NSTEACS) and ST-segment elevation myocardial infarction (STEMI)), stable angina pectoris (SAP), and controls. The Gensini score was used to estimate the severity of CAD. Additionally, 54 patients with CAD were medicated with rosuvastatin, 5 or 10 mg once daily, and then checked at 6 months.

RESULTS

The highest level of CEM was found in the STEMI group, followed by the NSTEACS, the SAP, and the control groups. Gensini score in group IV (CEM > 141.6 μg/mg) was markedly higher compared with group I (CEM ≤77.6 μg/mg). Gensini scores in group II (77.6 < CEM ≤111.1 μg/mg) and group III (111.1 < CEM ≤141.6 μg/mg) were also higher than in group I (all P < 0.001). Furthermore, a positive correlation was found between CEM levels and Gensini score (r = 0.714, P < 0.001). CEM levels were dose-dependently reduced by rosuvastatin therapy.

CONCLUSIONS

CEM levels are positively associated with the severity of CAD, meaning that CEM might contribute to the development of CAD. Importantly, rosuvastatin could decrease CEM levels in patients with CAD and might effectively help to attenuate the progression of CAD.

Sonographic characteristics of carotid artery plaques: Implications for follow-up planning?

The aim of our study was to analyze the ultrasound characteristics of carotid plaques in an outpatient population and to determine their implications for planning the ultrasound follow-up.

MATERIALS AND METHODS

We studied 747 consecutive outpatients (397 [53%] of whom were women) who underwent color Doppler sonography of the carotid arteries. Most of the patients presented multiple cardiovascular risk factors or were being followed-up for carotid artery stenosis.

RESULTS

Stenosis ranging from 1% to 69% was observed at the level of the right internal carotid arteries (ICA) in 419 (56.1%) of the 747 patients and in the left ICA in 408 of 747 (54.5%). One hundred twenty-four (29.5%) of the 419 RICA plaques and 77 (18.8%) of the 408 LICA plaques were classified as type 1 or type 2 according to the modified Gray-Weale classification.

CONCLUSIONS

Type 1 and type 2 plaques, which are referred to as "vulnerable plaques," were found in 160 (21.4%) of the 747 patients we examined. These patients should be subjected to closer ultrasound follow-up, even if they have only moderate carotid artery stenosis.

Lipoprotein(a) and family history of cardiovascular disease in children with familial dyslipidemias

OBJECTIVE

To investigate in children and adolescents with familial dyslipidemias the association between lipoprotein(a) [Lp(a)] level and family history of cardiovascular disease (CVD), and whether this association is independent of the disturbed lipid profile.

STUDY DESIGN

Lp(a) level, lipid profile, and a 2-generation genealogic tree to detect cardiovascular events were evaluated in 231 patients with familial dyslipidemias. Lp(a) levels were stratified according to presence, age of occurrence, and number and type of cardiovascular events in the patient's kindreds.

RESULTS

Lp(a) and other plasma lipid fractions did not differ between patients with and those without a family history of cardiovascular events. However, the percentage of patients with elevated Lp(a) level (≥85th percentile) was higher in those with a positive family history for early cardiovascular events (P = .01). Lp(a) level was a significant independent predictor of the number of premature cardiovascular events (β = 0.17; P = .01) and of cerebrovascular events in kindreds (OR, 2.5; 95% CI, 1.05-6.03; P = .039), independent of plasma lipid fractions and other cardiovascular risk factors.

CONCLUSIONS

In children and adolescents with familial dyslipidemias, the overall association between Lp(a) level and family history of early CVD may be due to a threshold effect in those with the highest Lp(a) levels. However, multiple cardiovascular events and cerebrovascular events are predicted by any increase in plasma Lp(a) level, independent of other cardiovascular risk factors.

Role of investigating thrombophilic disorders in young stroke

Our knowledge about various inherited and acquired causes of thrombophilic disorders has increased significantly during the past decade. Technology for various diagnostic tests for these rare disorders has matched the rapid advances in our understanding about the thrombophilic disorders. Inherited thrombophilic disorders predispose young patients for various venous or arterial thrombotic and thromboembolic episodes. Our understanding has also improved about various gene-gene and gene-environment interactions and their impact on the resultant heterogenous clinical manifestations. We describe various thrombophilic disorders, their diagnostic tests, pathogenic potential in isolation or with other concurrent inherited/acquired defects and possible therapeutic and prophylactic strategies. Better understanding, optimal diagnostic and screening protocols are expected to improve the diagnostic yield and help to reduce morbidity, disability, and mortality in relatively younger patients harbouring these inherited and acquired thrombophilic disorders.