The "dual-pathway" strategy after acute coronary syndrome: rivaroxaban and antiplatelet agents in the ATLAS ACS 2-TIMI 51 trial

Synergistic inhibitory effects of clopidogrel and rivaroxaban on platelet function and platelet-dependent thrombin generation in cats

BACKGROUND

Dual antithrombotic treatment (DAT) with clopidogrel and rivaroxaban sometimes is prescribed to cats with hypertrophic cardiomyopathy at risk of thromboembolism. To date, no studies have evaluated their combined effects on platelet function.

OBJECTIVES/HYPOTHESIS

Evaluate the safety of DAT in healthy cats and compare, ex vivo, platelet-dependent thrombin generation and agonist-induced platelet activation and aggregation in cats treated with clopidogrel, rivaroxaban, or DAT. We hypothesized that DAT would safely modulate agonist-induced platelet activation and aggregation more effectively than single agent treatment.

ANIMALS

Nine apparently healthy 1-year-old cats selected from a research colony.

METHODS

Unblinded, nonrandomized ex vivo cross-over study. All cats received 7 days of rivaroxaban (0.6 ± 0.1 mg/kg PO), clopidogrel (4.7 ± 0.8 mg/kg PO), or DAT with defined washout periods between treatments. Before and after each treatment, adenosine diphosphate (ADP)- and thrombin-induced platelet P-selectin expression was evaluated using flow cytometry to assess platelet activation. Platelet-dependent thrombin generation was measured by fluorescence assay. Platelet aggregation was assessed using whole blood impedance platelet aggregometry.

RESULTS

No cats exhibited adverse effects. Of the 3 treatments, only DAT significantly decreased the number of activated platelets (P = .002), modulated platelet activation in response to thrombin (P = .01), dampened thrombin generation potential (P = .01), and delayed maximum reaction velocity (P = .004) in thrombin generation. Like clopidogrel, DAT inhibited ADP-mediated platelet aggregation. However, rivaroxaban alone resulted in increased aggregation and activation in response to ADP.

CONCLUSION AND CLINICAL IMPORTANCE

Treatment combining clopidogrel and rivaroxaban (DAT) safely decreases platelet activation, platelet response to agonists, and thrombin generation in feline platelets more effectively than monotherapy with either clopidogrel or rivaroxaban.

Trends in Off-Label Indications of Non-Vitamin K Antagonist Oral Anticoagulants in Acute Coronary Syndrome

Acute coronary syndrome (ACS) is a leading cause of mortality worldwide. Despite optimal antiplatelet therapy recommendation after ischemic events, recurrent thrombotic complications rate remains high. The recurrent events maybe in part due to increased thrombin levels during ACS which may underscore the need for an additional anticoagulation therapy. Given the advantages of non-vitamin K antagonist oral anticoagulants (NOACs) over warfarin, they have the potential to prevent thrombus formation, in the presence or absence of atrial fibrillation, but at the cost of increased risk of bleeding. NOACs have also shown a promising efficacy in managing left ventricular thrombus and a potential benefit in avoiding stent thrombosis after percutaneous coronary revascularization. Taken as a whole, NOACs are increasingly used for off-licence indications, and continue to evolve as essential therapy in preventing and treating thrombotic events. Herein, this review discusses NOACs off-label indications in the setting of ischemic coronary disease.

Patients with acute and chronic coronary syndromes have elevated long-term thrombin generation

Coronary artery disease is a leading cause of morbidity and mortality worldwide. Despite significant advances in revascularization strategies and antiplatelet therapy with aspirin and/or P2Y₁₂ receptor antagonist, patients with acute coronary syndrome (ACS) continue to be at long-term risk of further cardiovascular events. Besides platelet activation, the role of thrombin generation (TG) in atherothrombotic complications is widely recognized. In this study, we hypothesized that there is an elevation of coagulation activation persists beyond 12 months in patients with ACS and chronic coronary syndrome (CCS) when compared with healthy controls. We measured TG profiles of patients within 72 h after percutaneous coronary intervention, at 6-month, 12-month and 24-month. Our results demonstrated that TG of patients with ACS (n = 114) and CCS (n = 40) were persistently elevated when compared to healthy individuals (n = 50) in peak thrombin (ACS 273.1 nM vs CCS 287.3 nM vs healthy 234.3 nM) and velocity index (ACS 110.2 nM/min vs CCS 111.0 nM/min vs healthy 72.9 nM/min) at 24-month of follow-up. Our results suggest a rationale for addition of anticoagulation to antiplatelet therapy in preventing long-term ischemic events after ACS. Further research could clarify whether the use of TG parameters to enable risk stratification of patients at heightened long-term procoagulant risk who may benefit most from dual pathway inhibition.

Aspirin and low-dose rivaroxaban - the dual pathway concept in patients with stable atherosclerotic disease: a comprehensive review

INTRODUCTION

Cardiovascular disease is the leading cause of morbidity and mortality in adults in western nations. In the last decades, tremendous research has been conducted in the field of secondary prevention in order to reduce recurrent cardiovascular events. This review summarizes the novel dual pathway concept of aspirin and very low-dose rivaroxaban, from mechanisms to clinical practice.

AREAS COVERED

The COMPASS trial demonstrated that in patients with stable atherosclerotic disease, very low-dose rivaroxaban, a direct factor Xa inhibitor, when combined with aspirin, reduced the rate of recurrent ischemic events, at the cost of increased bleeding. This effect was present in patients with ischemic heart disease, as well as in patients with atherosclerosis in other beds, such as in peripheral arterial disease. Sub-studies from the COMPASS trial examined other high-risk populations who might benefit the most from this regimen.

EXPERT OPINION

There are currently multiple antiplatelet and anticoagulation treatment regimens for patients with stable atherosclerotic disease. The dual pathway concept is a novel approach that combines both mechanisms. Identifying patients who might benefit the most in terms of ischemic events at the least bleeding events still remains a challenge, yet prescribing this combination to high-risk patients might be the most effective.

Immunoglobulin G (IgG) anticardiolipin antibodies and recurrent cardiovascular events. A systematic review and Bayesian meta-regression analysis

BACKGROUND

Anticardiolipin antibodies of the immunoglobulin G isotype (IgG aCL) have been suggested as risk factor for arterial and venous thrombosis. No conclusive data in patients with coronary artery disease (CAD) do exist. We investigate the risk of recurrent CAD according to the presence of IgG aCL.

METHODS

We performed a systematic review and meta-analysis to evaluate the risk of recurrent major adverse cardiac events (MACE) associated with the presence of IgG aCL in patients with CAD. MEDLINE and Cochrane databases were searched. We conducted a meta-analysis of the relative risk (RR) both at 12 and 24 months.

RESULTS

We included 11 eligible studies with a total of 2425 patients, 283 IgG aCL+ and 2142 IgG aCL-. The prevalence of IgG aCL+ ranged from 6.1% to 43.3%. A total of 341 cardiac events were reported: 71 (25.1%) in IgG aCL+ and 270 (12.6%) in IgG aCL- patients. We found an increased risk of recurrent MACE in patients with high IgG aCL both at 12 (RR 2.17, 2.5-97.5%CI, 1.54-3.00) and 24 months (RR 2.11, 2.5-97.5%CI, 1.62-2.66). This association was even stronger in patients with juvenile CAD (i.e. <50 years) at both 12 (RR 3.21, 2.5-97.5%CI, 1.74-5.41) and 24 months (RR 3.24, 2.5-97.5%CI, 1.84-5.21).

CONCLUSION

Patients with CAD and elevated IgG aCL have a doubled risk of recurrent MACE at 12 and 24 months. The presence of aCL should be suspected in patients with recurrent CAD events or in patients with juvenile CAD.

Short- and long-term follow-up of antithrombotic management patterns in patients hospitalized with acute coronary syndrome: Indian subgroup of EPICOR Asia study

Background

Acute coronary syndrome (ACS) is associated with emergency hospitalizations, and there are limited real-world data on clinical outcomes in post-ACS Asian patients. This article presents data on the Indian subgroup from the Long-term Follow-up of Antithrombotic Management Patterns in Acute Coronary Syndrome Patients in Asia (EPICOR-Asia) study.

Methods

EPICOR included patients with ACS [ST-segment elevation myocardial infarction (STEMI), non–ST-segment elevation myocardial infarction (NSTEMI), or unstable angina (UA)]. The study had two phases: acute phase and follow-up phase. The primary objective was to describe short- and long-term antithrombotic management patterns.

Results

EPICOR-India enrolled 2468 patients (STEMI-1482; NSTEMI-562; and UA-424). Cardiovascular risk factors were present in 1362 (55.2%) patients. Prehospital care was received by 879 (35.6%) patients, and the median time from the symptom onset to the first medical attention was 3 h (0.08, 100.33). The most common drug regimen prescribed during the acute phase was ≥2 antiplatelet agents + anticoagulants with no glycoprotein IIb/IIIa inhibitors and at discharge were aspirin + clopidogrel. About 78.8% of patients were discharged on dual antiplatelet therapy (DAPT) and 16%, on single antiplatelet therapy (SAPT). At 23 months after discharge, 55.6% were on DAPT, while 16.4% were on SAPT. Postdischarge outcomes at 2 years included death in 165 (6.7%) patients, composite events of death, myocardial infarction (MI), or ischemic stroke in 182 (7.4%) patients, and bleeding events in seven (0.3%) patients.

Conclusion

This study showed a gap between international recommendations and implementation for managing ACS in Indian patients. Most of the patients prefer to undergo invasive management instead of non-invasive therapy. At the end of the 2-year follow-up, more than half of the population was receiving DAPT, with most patients on receiving a combination of aspirin and clopidogrel. The mortality along with composite events of death, MI, or ischemic stroke was highest for patients with NSTEMI.

Oral anticoagulant use in cardiovascular disorders: a perspective on present and potential indications for rivaroxaban

BACKGROUND

Four non-vitamin-K-antagonist oral anticoagulants (NOACs) have been approved for use in various cardiovascular indications. The direct thrombin inhibitor dabigatran and the direct factor Xa inhibitors apixaban, edoxaban and rivaroxaban are now increasingly used in clinical practice. For some of these agents, available data from real-world studies support the efficacy and safety data in phase III clinical trials.

OBJECTIVES

This review aims to summarize the current status of trials and observational studies of oral anticoagulant use over the spectrum of cardiovascular disorders (excluding venous thrombosis), provide a reference source beyond stroke prevention for atrial fibrillation (AF) and examine the potential for novel applications in the cardiovascular field.

METHODS

We searched the recent literature for data on completed and upcoming trials of oral anticoagulants with a particular focus on rivaroxaban.

RESULTS

Recent data in specific patient subgroups, such as patients with AF undergoing catheter ablation or cardioversion, have led to an extended approval for rivaroxaban, whereas the other NOACs have ongoing or recently completed trials in this setting. However, there are unmet medical needs for several arterial thromboembolic-related conditions, including patients with: AF and acute coronary syndrome, AF and coronary artery disease undergoing elective percutaneous coronary intervention, coronary artery disease and peripheral artery disease, implanted cardiac devices, and embolic stroke of unknown source.

CONCLUSION

NOACs may provide alternative treatment options in areas of unmet need, and numerous studies are underway to assess their benefit-risk profiles in these settings.

Protective, repairing and fibrinolytic effects of rivaroxaban on vascular endothelium

AIMS

Rivaroxaban, a direct inhibitor of activated factor X (FXa), is the only new oral anticoagulant approved for secondary prevention after acute coronary syndrome. Our objective was to identify the possible molecular mechanisms of rivaroxaban that contribute to endothelial function.

METHODS

Cell viability and growth of human umbilical vein endothelial cells (HUVEC) were registered. Gene expression studies comparing the effects of rivaroxaban and FXa were conducted by a selective RNA array and confirmed by protein quantification. Wound-healing experiments on HUVEC, platelet adhesion, enzymatic activity, and cell-based assays for fibrin formation were performed with rivaroxaban.

RESULTS

Rivaroxaban (50 nM) only altered (>2 fold change) the expression of matrix metallopeptidase 2 and urokinase plasminogen activator (u-PA), but counteracted the FXa (9 nM)-induced upregulation of several pro-inflammatory genes (P < 0.05) and FXa-enhanced platelet adhesion over HUVEC. Rivaroxaban increased u-PA protein expression in HUVEC supernatants and enhanced u-PA activity (up to 4 IU ng^-1 of u-PA). Rivaroxaban (1 nM-1 μM) showed a significant and dose-dependent positive effect on HUVEC growth that was inhibited by BC-11-hydroxibromide, an inhibitor of u-PA. Healing properties after a wound on HUVEC cultures, and fibrinolytic properties were also shown by rivaroxaban. Both effects were reversed by BC-11-hydroxibromide.

CONCLUSIONS

Rivaroxaban enhanced viability, growth and migration of HUVEC, mainly by u-PA activation and upregulation, which also participate in the rivaroxaban-induced fibrinolytic activity at endothelial level. Rivaroxaban also protected from the pro-inflammatory effects of FXa on HUVEC. Altogether may improve endothelial functionality and could contribute to the cardiovascular benefits of rivaroxaban.

[Perioperative anticoagulation with NOAC using the example of rivaroxaban]

BACKGROUND

Recent findings require an update of earlier recommendations on the perioperative management of non Vitamin K antagonist oral anticoagulants (NOAC).

METHOD

The present position paper summarises the outcomes of an expert panel discussion.

RESULTS AND CONCLUSIONS

Based on the pharmacokinetic profile of rivaroxaban, a preoperative interruption of 24-72 hours is recommended depending on the patient's renal function, as well as individual and surgery-related bleeding risks. Similar NOAC-free intervals are recommended for patients with epidural catheters. Elective surgery should be delayed accordingly. A low molecular weight heparin (LMWH) "bridging" (in fact "switching") should be avoided because of an increased bleeding risk. Six to 8 hours after the intervention rivaroxaban can be re-initiated or, in case of more extensive interventions or an increased bleeding risk, after 24-72 hours; if necessary this interval could by bridged with LMWH, e. g. if the thromboembolic risk is considered high. In case of emergency surgery with a rivaroxaban pause of less than 9 hours, one should be prepared for a bleeding management including the use of prothrombin concentrate (PCC). Coagulation tests have no value for predicting perioperative bleeding, in contrast to a standardised bleeding history. As an overall estimate, the PT (Quick) can be determined with a suitable reagent. Currently, rivaroxaban-specific measurements of anti Xa levels are available at few specialised centres only. Moderate to severe haemorrhages can usually be managed by temporary interruption of rivaroxaban in conjunction with local and general haemostatic measures. Life-threatening bleeding events require a specific haemostasis management including the administration of PCC; these events are rare and usually have a favourable prognosis, except for intracranial haemorrhages.