Inhibitors of Protein Convertase Subtilisin/Kexin 9 (PCSK9) and Acute Coronary Syndrome (ACS): The State-of-the-Art

Role of PCSK9 inhibitors in the management of dyslipidaemia

Proprotein convertase subtilisin kexin9 (PCSK9) inhibitors are novel agents that lower LDL cholesterol and reduce cardio-vascular event rate. Being expensive, these agents are reserved for those with high risk or very high risk of CV events and with suboptimal response to statins and ezetimibe, with or without bempedoic acid or those intolerant to statins.

Safety and Efficacy of Proprotein Convertase Subtilisin-Kexin Type 9 Inhibitors After Acute Coronary Syndrome: A Meta-analysis of Randomized Controlled Trials

BACKGROUND

Elevated circulating cholesterol levels in patients with acute coronary syndrome (ACS) increase morbidity and mortality. Recent studies reported that PCSK9 inhibitors (PCSK9i) have a beneficial effect on various domains of patients' lipid profiles and cardiovascular and mortality outcomes. Here, we aim to further investigate the efficacy and safety of PCSK9i in patients with ACS or who experienced recent episodes.

METHODS

We comprehensively searched PubMed, Scopus, Web of Science and Cochrane CENTRAL to identify all randomized controlled trials comparing PCSK9i versus placebo. Data were extracted and analysed using Stata/MP version 17.0.

RESULTS

Eleven studies (n = 24,732) were included in this meta-analysis. In terms of efficacy outcomes, compared with the control group, PCSK9i significantly decreased levels of LDL-C, TC, TG, Lp (a) and Apo-B, with the following values, respectively: Cohen's d of - 1.25, 95% confidence interval (CI - 1.64 to - 0.87); Cohen's d of - 1.32, 95% CI (- 1.83 to - 0.81); Cohen's d of - 0.26, 95% CI (- 0.37 to - 0.14); Cohen's d of - 0.70, 95% CI (- 1.15 to - 0.26); and Cohen's d of - 1.46, 95% CI (- 1.97 to - 0.94). The levels of HDL-C and Apo-A1 increased by: Cohen's d 0.27, 95% CI (0.16-0.39) and Cohen's d of 0.30, 95% CI (0.17-0.42), respectively. Regarding safety outcomes, PCSK9i was associated with lower odds of myocardial infarction (MI) and cerebrovascular events with the following values, respectively: OR = 0.87, 95% CI (0.78-0.97) and OR = 0.71, 95% CI (0.52-0.98).

CONCLUSIONS

PCSK9i was associated with better lipid profile and quality of life of patients and can be recommended as an optimal treatment strategy. Further trials should study combinations of PCSK9i with other lipid-lowering drugs.

Alirocumab effect on preventing periprocedural ischaemic events in coronary heart disease patients undergoing coronary stenting (APPEASE trial): study protocol of a multicentre, open-label, randomised controlled trial

INTRODUCTION

Percutaneous coronary intervention (PCI)-related myocardial infarction (type 4a MI) and major periprocedural myocardial injury have been demonstrated leading to poor prognosis of patients with coronary heart disease (CHD) undergoing elective PCI and still remain high occurrence even after the therapy of dual antiplatelet agents and statins. Proprotein convertase subtilisin/kexin type 9 inhibitor alirocumab has been shown to be effectively in reducing the risk of acute MI (AMI). However, the effect of alirocumab on preventing PCI-related MI or major periprocedural myocardial injury in patients with CHD undergoing elective PCI remains uncertain.

METHODS AND ANALYSIS

Alirocumab effect on Preventing Periprocedural ischaemic Events in coronary heart diseAse patients undergoing coronary StEnting trial is a multicentre, open-label, randomised controlled trial aiming to determine whether alirocumab could reduce the incidence of type 4a MI or major periprocedural myocardial injury in patients with CHD undergoing elective PCI. In total, 422 non-AMI CHD patients planned to undergo elective PCI will be randomly assigned to receive standard pharmacotherapy of CHD (control group) or additional use of subcutaneous alirocumab 75 mg 1 day before procedure (alirocumab group). The primary outcome is type 4a MI or major periprocedural myocardial injury defined as high-sensitivity cardiac troponin elevating above 5×99 th percentile upper reference limit in 48 hours after PCI. Patients will continue receiving standard pharmacotherapy or additional biweekly subcutaneous alirocumab 75 mg for 3 months according to the initial randomisation group. We will follow up for 3 months and record all the major adverse cardiovascular events (MACEs). Incidence of PCI-related MI or major periprocedural myocardial injury, and MACE in 3 months after PCI will be compared between control group and alirocumab group.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the Medical Ethics Committee of the Third Affiliated Hospital of Sun Yat-sen University with approval number: (2022)02-140-01. The results of this study will be reported through peer-reviewed journals and conference presentations.

TRIAL REGISTRATION NUMBER

ChiCTR2200063191.

Revascularization and Medical Therapy for Chronic Coronary Syndromes: Lessons Learnt from Recent Trials, a Literature Review

Stable coronary artery disease (CAD) has recently been replaced by a new entity described as chronic coronary syndrome (CCS). This new entity has been developed based on a better understanding of the pathogenesis, the clinical characteristics, and the morbi-mortality associated to this condition as part of the dynamic spectrum of CAD. This has significant implications in the clinical management of CCS patients, that ranges from lifestyle adaptation, medical therapy targeting all the elements contributing to CAD progression (i.e., platelet aggregation, coagulation, dyslipidaemia, and systemic inflammation), to invasive strategies (i.e., revascularization). CCS is the most frequent presentation of coronary artery disease which is the first cardiovascular disease worldwide. Medical therapy is the first line therapy for these patients; however, revascularization and especially percutaneous coronary intervention remains beneficial for some of them. European and American guidelines on myocardial revascularization were released in 2018 and 2021, respectively. These guidelines provide different scenarios to help physicians choose the optimal therapy for CCS patients. Recently, several trials focusing on CCS patients have been published. We sought to synthetize the place of revascularization in CCS patients according to the latest guidelines, the lessons learnt from recent trials on revascularization and medical therapy, and future perspectives.

Reduction of Cardiovascular Risk Using Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors in Patients With Acute Coronary Syndrome: A Systematic Review

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a hepatic enzyme that regulates blood cholesterol levels by degrading low-density lipoprotein (LDL) receptors from the surface of hepatocytes. Studies have shown that inhibiting this molecule decreases the cardiovascular risk in individuals with atherosclerotic cardiovascular disease (ASCVD) by lowering low-density lipoprotein cholesterol (LDL-C). Two major cardiovascular outcome trials showed that the use of the PCSK9 inhibitors (alirocumab and evolocumab) in patients with recent acute coronary syndrome (ACS) is associated with a lower risk of further cardiovascular (CV) events. Information regarding the use of these monoclonal antibodies for primary prevention has also been reported by these trials. The goal of this systematic review is to describe the mechanism of PCSK9 inhibitors and further discuss their ability to reduce CV risk in high-risk populations. The search strategy was used in a systematic way using PubMed Central, Google Scholar, and ScienceDirect. We included randomized control trials (RCTs), systematic reviews, and narrative reviews in English published in the last five years. Observational studies, case reports, and case studies were excluded. The quality of the studies was evaluated using the Cochrane Collaboration Risk of Bias Tool, Assessment of Multiple Systematic Reviews 2, and Scale for the Assessment of Narrative Review Articles. A total of 10 articles were included in this systematic review. These included an RCT, a systematic review, and eight narrative reviews. Our study suggested that adding PCSK9 inhibitors to background statin therapy for selected patients with high-risk factors demonstrated substantial benefits in reducing overall CV morbidity and mortality after ACS. Multiple studies have demonstrated the short-term safety of low LDL-C levels caused by these drugs. However, long-term safety must be assessed with further studies.

PCSK9 inhibitors for acute coronary syndrome: the era of early implementation

Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, a new cholesterol-lowering strategy, can decrease low-density lipoprotein cholesterol (LDL-C) levels by inhibiting PCSK9 and reducing the degradation of LDL receptors; thus, they are impacting the management of dyslipidemia to the prevention of cardiovascular events. Recent guidelines recommend PCSK9 inhibitors for patients who fail to achieve target lipids after ezetimibe/statin therapy. As PCSK9 inhibitors have been demonstrated to significantly and safely reduce LDL-C, discussions have begun to explore its optimal timing in coronary artery disease, especially in subjects with acute coronary syndrome (ACS). Also, their additional benefits, such as anti-inflammatory effects, plaque regression effects, and cardiovascular event prevention, have become the focus of recent research. Several studies, including EPIC-STEMI, suggest the lipid-lowering effects of early PCSK9 inhibitors in ACS patients, while some studies such as PACMAN-AMI suggest that early PCSK9 inhibitors can decelerate plaque progression and reduce short-term risks of cardiovascular events. Thus, PCSK9 inhibitors are entering the era of early implementation. In this review, we are committed to summarizing the multidimensional benefits of early implementation of PCSK9 inhibitors in ACS.

Reduction of cerebrovascular and peripheral events with PCSK9 inhibitors: Does it just depend on the lowering of the low-density lipoprotein?

Atherosclerotic cardiovascular disease is a systemic condition involving several vascular districts. The most involved vascular bed, beyond the coronary district, is represented by the peripheral arteries, whose involvement can give rise to cerebrovascular or peripheral events. PCSK9 inhibitors (PCSK9i) have established themselves as safe and effective drugs in reducing cholesterol linked to low-density lipoprotein (LDL-C), a causative factor of disease, with a consequent reduction in cardiovascular events. The two main studies on anti-PCSK9 antibodies, the FOURIER study for evolocumab and the ODYSSEY OUTCOMES study for alirocumab, highlighted the effectiveness in reducing LDL-C levels and its translation in a lower event rate of around 15%. Sub-analysis of these two trials showed how PCSK9i prevent cerebrovascular and/or peripheral events and how patients with already known cerebrovascular or peripheral disease benefit more from the action of these drugs than patients who do not have a widespread disease. Current evidence suggests that the preventive action of cerebrovascular and peripheral events is mainly expressed through reducing LDL-C levels. Although there are data regarding the association of PCSK9 levels and inflammatory status, propensity for thrombosis and platelet aggregation, these are currently less robust and do not justify a cardiovascular event reduction action that is independent of the action on LDL-C.

Dyslipidemia in Transplant Patients: Which Therapy?

Cardiovascular disease is the most important cause of death worldwide in recent years; an increasing trend is also shown in organ transplant patients subjected to immunosuppressive therapies, in which cardiovascular diseases represent one of the most frequent causes of long-term mortality. This is also linked to immunosuppressant-induced dyslipidemia, which occurs in 27 to 71% of organ transplant recipients. The aim of this review is to clarify the pathophysiological mechanisms underlying dyslipidemia in patients treated with immunosuppressants to identify immunosuppressive therapies which do not cause dyslipidemia or therapeutic pathways effective in reducing hypercholesterolemia, hypertriglyceridemia, or both, without further adverse events.

Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors Use for Atherogenic Dyslipidemia in Solid Organ Transplant Patients

Dyslipidemia is a widespread risk factor in solid organ transplant patients, due to many reasons, such as the use of immunosuppressive drugs, with a consequent increase in cardiovascular diseases in this population. PCSK9 is an enzyme mainly known for its role in altering LDL levels, consequently increasing cardiovascular risk. Monoclonal antibody PCSK9 inhibitors demonstrated remarkable efficacy in the general population in reducing LDL cholesterol levels and preventing cardiovascular disease. In transplant patients, these drugs are still poorly used, despite having comparable efficacy to the general population and giving fewer drug interactions with immunosuppressants. Furthermore, there is enough evidence that PCSK9 also plays a role in other pathways, such as inflammation, which is particularly dangerous for graft survival. In this review, the current evidence on the function of PCSK9 and the use of its inhibitors will be discussed, particularly in transplant patients, in which they may provide additional benefits.

Pleiotropic Effects of PCSK9: Focus on Thrombosis and Haemostasis

The proprotein convertase subtilisin/keying 9 (PCSK9) is a serine protease that has gained importance in recent years as a drug target, mainly due to its effect on cholesterol metabolism in promoting the degradation of the low-density lipoprotein receptor (LDLR). However, this protease may also play an important role in lipid-independent reactions, including the process of thrombogenesis. Considering this, we reviewed the effects and implications of PCSK9 on platelet function and blood coagulation. PCSK9 knockout mice exhibited reduced platelet activity and developed less agonist-induced arterial thrombi compared to the respective control animals. This is in line with known research that elevated blood levels of PCSK9 are associated with an increased platelet reactivity and total number of circulating platelets in humans. Moreover, PCSK9 also has an effect on crucial factors of the coagulation cascade, such as increasing factor VIII plasma levels, since the degradation of this blood clotting factor is promoted by the LDLR. The aforementioned pleiotropic effects of the PCSK9 are important to take into account when evaluating the clinical benefit of PCSK9 inhibitors.

Association Between Circulating Proprotein Convertase Subtilisin/Kexin Type 9 Concentrations and Cardiovascular Events in Cardiovascular Disease: A Systemic Review and Meta-Analysis

Background: A large amount of evidence suggests that proprotein convertase subtilisin/Kexin type 9 (PCSK9) inhibitors have clinical benefits in patients with cardiovascular disease (CVD). However, whether PCSK9 concentrations predict future cardiovascular (CV) events remains unclear.

Methods: We conducted a meta-analysis to investigate the ability of PCSK9 concentrations to predict future CV events in patients with established CVD. A comprehensive search of electronic databases was conducted in June 2021. We included relative risk (RR) estimates with 95% CI or events of interest.

Results: Eleven cohort studies including 8,471 patients with CVD were enrolled. The pooled RR of CV events for the increase in the circulating baseline PCSK9 concentrations by 1 SD showed a positive association in a random-effect model (RR 1.226, 95% CI: 1.055–1.423, P = 0.008). Similarly, the risk of the total CV events increased by 52% in the patients in the highest tertile compared with those in the lowest tertile of circulating PCSK9 concentrations (RR 1.523, 95% CI: 1.098–2.112, P = 0.012). The association between PCSK9 and CV events was stronger in stable patients with CVD, patients treated with statins, and Asian patients.

Conclusions: High PCSK9 concentrations are significantly related to the increased risk of future CV events. These results enrich the knowledge of PCSK9 function and suggest the further possible clinical role of PCSK9 inhibitors.