Lipoprotein(a), a Lethal Player in Calcific Aortic Valve Disease

Poor Sympathetic Compensation During Active Standing Increases the Risk of Morbidity-Mortality in the Post-Surgery of Patients with Severe Calcific Aortic Stenosis

(1) Background: Although all severe calcific aortic stenosis (SCAS) patients have decreased sympathetic compensation to active standing, it has not been studied in patients who underwent aortic valve replacement (AVR). The objective was to assess the association of the heart rate variability (HRV) response to an active orthostatic challenge before AVR with the risk of complications or death during the AVR postoperative period in patients with SCAS. (2) Methods: This observational study included 49 patients. The cardiac autonomic activity was assessed by HRV analysis during supine position and active standing (five minutes each). (3) Results: Twenty-four patients (48.9%) who presented outcomes (complication or death) had a greater left ventricular (LV) mass and a smaller magnitude of change during active standing in both the mean cardiac period and sympathetic predominance. Poor sympathetic compensation to active standing and LV mass were independently associated with the outcome odds ratio (OR) = 4.8 [(1.06, 21.8), p < 0.041] and 1.03 [(1.007, 1.062), p < 0.013], respectively. (4) Conclusions: In SCAS patients, poor sympathetic compensation in the face of orthostatic challenge and greater LV mass are associated with complications or death after AVR surgery. This approach offers an opportunity to find new criteria to reduce the surgical risk of these patients.

Lipoprotein(a) and thromboembolism: current state of knowledge and unsolved issues

Lipoprotein(a) [Lp(a)], a low-density lipoprotein-like particle containing a highly polymorphic apolipoprotein(a) [apo(a)] homologous in > 80% to plasminogen, was identified as a genetically determined independent risk factor for cardiovascular disease. Elevated Lp(a) levels, found in about 20% of Europeans, are strongly linked to higher rates of myocardial infarction, major adverse cardiac events, accelerated plaque progression, ischemic stroke (especially in younger adults), and calcific aortic valve disease. However, its role in venous thromboembolism, including atypical locations like cerebral and retinal vein thrombosis, remains controversial despite several shared mechanisms underlying arterial and venous thromboembolism. The most robust evidence supports antifibrinolytic properties of elevated Lp(a), particularly smaller apo(a) isoforms, which inhibit plasminogen activation mainly by interacting with the tissue-type plasminogen activator, plasminogen, and fibrin. Other prothrombotic mechanisms include increased synthesis of plasminogen activator inhibitor (PAI-1), formation of denser fibrin networks composed of thinner fibers, less susceptible to lysis, increased platelet activation, enhanced oxidation of phospholipids leading to a low-grade proinflammatory state, upregulated tissue factor expression, and suppression of tissue factor pathway inhibitor. Targeted Lp(a) lowering therapies are currently being tested in randomized clinical trials and could potentially have clinically relevant antithrombotic effects, evidenced by the reduced risk of thromboembolism. This review summarizes the available data on the prothrombotic and antifibrinolytic actions of Lp(a), along with clinical evidence for the increased risk of thromboembolic events related to elevated Lp(a). It also introduces new concepts to explain discrepant clinical results regarding venous events, highlighting the impact of oxidized phospholipids on a prothrombotic state under conditions of high Lp(a).

Macrophages in Calcific Aortic Valve Disease: Paracrine and Juxtacrine Disease Drivers

A significant role in the pathogenesis of CAVD is played by innate immunity cells, such as macrophages. In stenotic valves, macrophages have enhanced inflammatory activity, and the population's balance is shifted toward pro-inflammatory ones. Pro-inflammatory macrophages release cytokines, chemokines, and microRNA, which can directly affect the resident valvular cells and cause valve calcification. In CAVD patients, macrophages may have more pronounced pro-inflammatory properties, enhanced not only by paracrine signals but also by juxtacrine Notch signaling and epigenetic factors, which influence the maturation of macrophages' progenitors. In this review, we observe the accumulated data on the involvement of macrophages in CAVD development via paracrine and juxtacrine interactions.

Lipoprotein(a) is a highly atherogenic lipoprotein: pathophysiological basis and clinical implications

PURPOSE OF REVIEW

Lipoprotein(a) has been identified as a causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and aortic valve stenosis. However, as reviewed here, there is ongoing debate as to the key pathogenic features of Lp(a) particles and the degree of Lp(a) atherogenicity relative to low-density lipoprotein (LDL).

RECENT FINDINGS

Genetic analyses have revealed that Lp(a) on a per-particle basis is markedly (about six-fold) more atherogenic than LDL. Oxidized phospholipids carried on Lp(a) have been found to have substantial pro-inflammatory properties triggering pathways that may contribute to atherogenesis. Whether the strength of association of Lp(a) with ASCVD risk is dependent on inflammatory status is a matter of current debate and is critical to implementing intervention strategies. Contradictory reports continue to appear, but most recent studies in large cohorts indicate that the relationship of Lp(a) to risk is independent of C-reactive protein level.

SUMMARY

Lp(a) is a highly atherogenic lipoprotein and a viable target for intervention in a significant proportion of the general population. Better understanding the basis of its enhanced atherogenicity is important for risk assessment and interpreting intervention trials.

The Role of Lp-PLA2 as a Mediator Between Serum Magnesium and Zinc Levels and Cardiovascular Risk in Patients With Metabolic Syndrome

BACKGROUND

Metabolic syndrome (MetS) is a collection of conditions that includes abdominal obesity, low high-density lipoprotein (HDL) levels, high triglycerides, hypertension, and impaired glucose metabolism, all of which are risk factors for cardiovascular diseases. Of the biomarkers above, lipoprotein-associated phospholipase A2 (Lp-PLA2) has been highlighted as a critical link between inflammation and the pathogenesis of atherosclerosis, which strongly predicts cardiovascular events. Micronutrients like magnesium and zinc are essential in maintaining metabolic and cardiovascular health, but these micronutrient deficiencies occur frequently among individuals with MetS. This study aimed to consider the association between serum magnesium and zinc levels with Lp-PLA2 and how these associations could link pathways in cardiovascular risk among MetS patients.

METHODS

This was a comparative cross-sectional study of 100 cases diagnosed as MetS and compared with an equal number (n = 100) of age and matched healthy control. Blood magnesium, zinc, and Lp-PLA2 levels were determined by colorimetric assay. We also tested the association of Lp-PLA2 with levels of micronutrients, and we evaluated whether Lp-PLA2 was a mediator in the pathway between MetS and cardiovascular risk. The data were analyzed on IBM Corp. Released 2021. IBM SPSS Statistics for Windows, Version 28.0. Armonk, NY: IBM Corp; the results will be considered statistically significant if p < 0.05.

RESULTS

The serum magnesium and zinc concentrations in patients with MetS were significantly lower than in the controls (p < 0.001). The Lp-PLA2 level was much higher in the MetS group than the no-MetS, and it correlated inversely with serum Mg (r = -0.35, p < 0.001) or Zn levels (r = -0.42, p < 0.001). After multivariate analysis, the mediating effect of Lp-PLA2 in the pathway from micronutrient deficiency to cardiovascular risk was maintained, whereby high levels were associated with increased atherogenic index and oxidative stress markers.

CONCLUSIONS

These results show that Lp-PLA2 is an intermediate step in the relationship between low levels of some micronutrients and cardiovascular risk among MetS patients. Our findings indicate that a sufficient magnesium and zinc status might offer cardiovascular protection through lessening Lp-PLA2 activity. These observations demonstrate the potential benefits of high-risk enrichment and dietary intervention for detecting and controlling micronutrient deficiencies in MetS subjects to impede further cardiovascular diseases.

Pathological Mechanism and Treatment of Calcified Aortic Stenosis

Calcified aortic stenosis (AS) is one of the most common valvular heart diseases worldwide, characterized by progressive fibrocalcific remodeling and thickening of the leaflets, which ultimately leads to obstruction of blood flow. Its pathobiology is an active and complicated process, involving endothelial cell dysfunction, lipoprotein deposition and oxidation, chronic inflammation, phenotypic transformation of valve interstitial cells, neovascularization, and intravalvular hemorrhage. To date, no targeted drug has been proven to slow down or prevent disease progression. Aortic valve replacement is still the optimal treatment of AS. This article reviews the etiology, diagnosis, and management of calcified aortic stenosis and proposes novel potential therapeutic targets.

Non-Conventional Risk Factors: "Fact" or "Fake" in Cardiovascular Disease Prevention?

Cardiovascular diseases (CVDs), such as arterial hypertension, myocardial infarction, stroke, heart failure, atrial fibrillation, etc., still represent the main cause of morbidity and mortality worldwide. They significantly modify the patients' quality of life with a tremendous economic impact. It is well established that cardiovascular risk factors increase the probability of fatal and non-fatal cardiac events. These risk factors are classified into modifiable (smoking, arterial hypertension, hypercholesterolemia, low HDL cholesterol, diabetes, excessive alcohol consumption, high-fat and high-calorie diet, reduced physical activity) and non-modifiable (sex, age, family history, of previous cardiovascular disease). Hence, CVD prevention is based on early identification and management of modifiable risk factors whose impact on the CV outcome is now performed by the use of CV risk assessment models, such as the Framingham Risk Score, Pooled Cohort Equations, or the SCORE2. However, in recent years, emerging, non-traditional factors (metabolic and non-metabolic) seem to significantly affect this assessment. In this article, we aim at defining these emerging factors and describe the potential mechanisms by which they might contribute to the development of CVD.

Approach to the Patient With a Suboptimal Statin Response: Causes and Algorithm for Clinical Management

CONTEXT

Statins are the lipid-lowering therapy of choice for the prevention of atherosclerotic cardiovascular disease (ASCVD) but their effectiveness in lowering low-density lipoprotein cholesterol (LDL-C) can substantially differ between individuals. In this mini-review, we describe the different causes for a suboptimal statin response and an algorithm for the diagnosis and clinical management of these patients.

EVIDENCE ACQUISITION

A PubMed search using the terms "statin resistance," "statin sensitivity," "statin pharmacokinetics," "cardiovascular disease," and "lipid-lowering therapies" was performed. Published papers in the past 10 years that were relevant to the topic were examined to provide content for this mini-review.

EVIDENCE SYNTHESIS

Suboptimal lowering of LDL-C by statins is a major problem in the clinical management of patients and limits the value of this therapeutic approach. There are multiple causes of statin hyporesponsiveness with compliance being the most common explanation. Other causes, such as analytical issues with LDL-C measurement and the presence of common lipid disorders (familial hypercholesterolemia, elevated lipoprotein[a] and secondary dyslipidemias) should be excluded before considering primary statin resistance from rare genetic variants in lipoprotein-related or drug-metabolism genes. A wide variety of nonstatin lipid-lowering drugs are now available and can be added to statins to achieve more effective LDL-C lowering.

CONCLUSIONS

The evaluation of statin hyporesponsiveness is a multistep process that can lead to the optimization of lipid-lowering therapy for the prevention of ASCVD. It may also lead to the identification of distinct types of dyslipidemias that require specific therapies and/or the genetic screening of family members.

Lipoprotein(a) and calcific aortic valve disease initiation and progression: a systematic review and meta-analysis

Although evidence indicates the association of lipoprotein(a) [Lp(a)] with atherosclerosis, the link with calcific aortic valve disease (CAVD) is unclear. This systematic review and meta-analysis explores the connection between Lp(a) and aortic valve calcification and stenosis (AVS). We included all relevant studies, indexed in eight databases, up to February 2023. A total of 44 studies (163 139 subjects) were included, with 16 of them being further meta-analysed. Despite considerable heterogeneity, most studies support the relationship between Lp(a) and CAVD, especially in younger populations, with evidence of early aortic valve micro-calcification in elevated-Lp(a) populations. The quantitative synthesis showed higher Lp(a) levels, by 22.63 nmol/L (95% CI: 9.98-35.27), for patients with AVS, while meta-regressing the data revealed smaller Lp(a) differences for older populations with a higher proportion of females. The meta-analysis of eight studies providing genetic data, revealed that the minor alleles of both rs10455872 and rs3798220 LPA gene loci were associated with higher risk for AVS (pooled odds ratio 1.42; 95% CI: 1.34-1.50 and 1.27; 95% CI: 1.09-1.48, respectively). Importantly, high-Lp(a) individuals displayed not only faster AVS progression, by a mean difference of 0.09 m/s/year (95% CI: 0.09-0.09), but also a higher risk of serious adverse outcomes, including death (pooled hazard ratio 1.39; 95% CI: 1.01-1.90). These summary findings highlight the effect of Lp(a) on CAVD initiation, progression and outcomes, and support the early onset of Lp(a)-related subclinical lesions before clinical evidence.

Oxidative stress and valvular endothelial cells in aortic valve calcification

Calcified aortic valve disease (CAVD) is a common cardiovascular disease in elderly individuals. Although it was previously considered a degenerative disease, it is, in fact, a progressive disease involving multiple mechanisms. Aortic valve endothelial cells, which cover the outermost layer of the aortic valve and are directly exposed to various pathogenic factors, play a significant role in the onset and progression of CAVD. Hemodynamic changes can directly damage the structure and function of valvular endothelial cells (VECs). This leads to inflammatory infiltration and oxidative stress, which promote the progression of CAVD. VECs can regulate the pathological differentiation of valvular interstitial cells (VICs) through NO and thus affect the process of CAVD. Under the influence of pathological factors, VECs can also be transformed into VICs through EndMT, and then the pathological differentiation of VICs eventually leads to the formation of calcification. This review discusses the role of VECs, especially the role of oxidative stress in VECs, in the process of aortic valve calcification.

Serum lipoprotein(a) predicts 1-year major cardiovascular events in patients after percutaneous coronary intervention

BACKGROUND

Lipoprotein(a) [Lp(a)], which is predictive of coronary heart disease (CHD), plays an important role in the pathogenesis of atherosclerosis. This study aimed to evaluate the association of Lp(a) with major adverse cardiovascular events (MACEs) and readmission in individuals who had undergone a percutaneous coronary intervention (PCI).

METHODS

A total of 1,938 patients with CHD who had undergone a PCI from January 2010 to December 2018 were assigned to three groups based on Lp(a) level. Follow-up was performed to assess the 1-year occurrence of MACEs and readmission.

RESULTS

Kaplan-Meier survival curves showed that the cumulative hazard incidence rate of MACEs and repeat PCI (re-PCI) significantly increased with Lp(a) level. Multivariate Cox proportional hazards regression analysis further confirmed Lp(a) as a significant independent predictor of MACEs. The area under the curve of the complex index risk score was significantly larger than those of other independent indicators. In individuals with low-density lipoprotein-cholesterol (LDL-C) levels either below 70 mg/dL or between 70 mg/dL and 100 mg/dL, Lp(a) was associated with increased rates of MACEs and readmission. In addition, a nomogram was constructed to predict 1-year MACE.

CONCLUSIONS

High Lp(a) levels may be a residual risk factor for MACEs in individuals with LDL-C levels under 100 mg/dL. Additionally, the built nomogram could predict 1-year MACEs with high accuracy. Lp(a) independently predicts 1-year MACEs, indicating its importance in risk assessment and the selection of clinical strategies in patients who have undergone a PCI.

Contribution of Oxidative Stress (OS) in Calcific Aortic Valve Disease (CAVD): From Pathophysiology to Therapeutic Targets

Calcific aortic valve disease (CAVD) is a major cause of cardiovascular mortality and morbidity, with increased prevalence and incidence. The underlying mechanisms behind CAVD are complex, and are mainly illustrated by inflammation, mechanical stress (which induces prolonged aortic valve endothelial dysfunction), increased oxidative stress (OS) (which trigger fibrosis), and calcification of valve leaflets. To date, besides aortic valve replacement, there are no specific pharmacological treatments for CAVD. In this review, we describe the mechanisms behind aortic valvular disease, the involvement of OS as a fundamental element in disease progression with predilection in AS, and its two most frequent etiologies (calcific aortic valve disease and bicuspid aortic valve); moreover, we highlight the potential of OS as a future therapeutic target.