Platelet P2Y12 inhibiting therapy in adjunct to vascular dose of rivaroxaban or aspirin: A pharmacodynamic study of dual pathway inhibition versus dual antiplatelet therapy

Therapeutic Potential of FXI Inhibitors: Hype or Hope?

Significant advancements have shaped the landscape of anticoagulant therapy in the past two decades, including the introduction of direct oral anticoagulants (DOACs), characterized by favorable safety and efficacy profiles and reduced drug-to-drug or food interaction resulting in excellent patient compliance. However, residual concerns still exist with standard-of-care anticoagulant therapy, including the inability to use DOACs in several clinical settings and the need to further reduce the risk of bleeding. Recent improvements in the understanding of the mechanisms behind thrombus formation have led to the awareness that the intrinsic pathway of the coagulation cascade may play an important role in pathological thrombosis, but not in hemostasis. This has represented the rationale for targeting this pathway with factor XI (FXI) inhibitors, with the aim of uncoupling hemostasis and thrombosis. Clinical evidence from patients with FXI deficiency further supports this concept. A number of compounds with different mechanisms of action have been developed to target FXI (i.e., asundexian, abelacimab, Ionis-FXIRx, milvexian, osocimab, and Xisomab 3G). To date, the majority of available trials have not gone beyond completion of phase 2 and results are conflictive making it difficult to appraise the clinical benefit of these compounds in the different clinical settings where they have been tested (i.e., atrial fibrillation, acute ischemic stroke, acute myocardial infarction, end-stage renal disease, total knee arthroplasty). Moreover, the largest phase 3 randomized trial designed to test the efficacy of asundexian over apixaban in patients with atrial fibrillation, the OCEANIC-AF, has been prematurely stopped as a result of the inferior efficacy of asundexian. In this review we discuss the pharmacological properties and available evidence generated thus far for factor XI inhibitors, providing a perspective on the current state of these drugs.

Platelet-fibrin clot strength and platelet reactivity predicting cardiovascular events after percutaneous coronary interventions

BACKGROUND AND AIMS

Platelet-fibrin clot strength (PFCS) is linked to major adverse cardiovascular event (MACE) risk. However, the association between PFCS and platelet reactivity and their prognostic implication remains uncertain in patients undergoing percutaneous coronary intervention (PCI).

METHODS

In PCI-treated patients (n = 2512) from registry data from January 2010 to November 2018 in South Korea, PFCS using thromboelastography and platelet reactivity using VerifyNow were measured. High PFCS (PFCSHigh) was defined as thromboelastography maximal amplitude ≥ 68 mm, and high platelet reactivity (HPR) was defined as >208 P2Y12 reaction units. Patients were stratified into four groups according to maximal amplitude and P2Y12 reaction unit levels: (i) normal platelet reactivity (NPR)-PFCSNormal (31.8%), (ii) HPR-PFCSNormal (29.0%), (iii) NPR-PFCSHigh (18.1%), and (iv) HPR-PFCSHigh (21.1%). Major adverse cardiovascular event (all-cause death, myocardial infarction, or stroke) and major bleeding were followed up to 4 years.

RESULTS

High platelet reactivity and PFCSHigh showed an additive effect for clinical outcomes (log-rank test, P < .001). Individuals with NPR-PFCSNormal, NPR-PFCSHigh, HPR-PFCSNormal, and HPR-PFCSHigh demonstrated MACE incidences of 7.5%, 12.6%, 13.4%, and 19.3%, respectively. The HPR-PFCSHigh group showed significantly higher risks of MACE compared with the NPR-PFCSNormal group [adjusted hazard ratio (HRadj) 1.89; 95% confidence interval (CI) 1.23-2.91; P = .004] and the HPR-PFCSNormal group (HRadj 1.60; 95% CI 1.12-2.27; P = .009). Similar results were observed for all-cause death. Compared with HPR-PFCSNormal phenotype, NPR-PFCSNormal phenotype was associated with a higher risk of major bleeding (HRadj 3.12; 95% CI 1.30-7.69; P = .010).

CONCLUSIONS

In PCI patients, PFCS and platelet reactivity demonstrated important relationships in predicting clinical prognosis. Their combined assessment may enhance post-PCI risk stratification for personalized antithrombotic therapy.

Impact of very low dose rivaroxaban in addition to dual antiplatelet therapy on endogenous fibrinolysis in acute coronary syndrome: The VaLiDate-R study

BACKGROUND

Impaired endogenous fibrinolysis is adverse cardiovascular risk factor in acute coronary syndrome (ACS) patients. Addition of very low dose rivaroxaban (VLDR) to dual antiplatelet therapy (DAPT) reduces cardiovascular events but increases bleeding.

OBJECTIVE

We aimed to assess whether addition of VLDR to DAPT can enhance endogenous fibrinolysis.

METHODS

In a prospective, open-label trial, we assessed endogenous fibrinolysis in whole blood, in 549 patients with ACS using the Global Thrombosis Test (GTT) and Thromboelastography (TEG). Patients (n = 180) who demonstrated impaired endogenous fibrinolysis (lysis time [LT] >2000s with the GTT) were randomised 1:1:1 to (i) clopidogrel 75 mg daily; (ii) clopidogrel 75 mg daily plus rivaroxaban 2.5 mg twice daily; or (iii) ticagrelor 90 mg twice daily, for 30 days, in addition to aspirin. Fibrinolytic status was assessed at 0, 2, 4 and 8 weeks. The primary outcome was the change in LT from admission to week 4. We also measured thrombotic occlusion time (OT) at high shear, and rivaroxaban level.

RESULTS

There was no difference between the groups with respect to LT or clot lysis with TEG, and no change in these parameters compared to baseline during study drug allocation. In the rivaroxaban plus clopidogrel group, OT was prolonged compared to the other groups, although rivaroxaban levels were low, suggesting non-compliance.

CONCLUSION

Addition of rivaroxaban 2.5 mg twice daily to DAPT does not affect endogenous fibrinolysis of thrombus formed at either high or low shear. Further studies are needed to determine whether higher doses of rivaroxaban can favourably modulate fibrinolysis.

CONDENSED ABSTRACT

Impaired endogenous fibrinolysis is a strong risk factor in ACS. We aimed to assess whether adding very low dose rivaroxaban (VLDR) to DAPT can enhance fibrinolysis. Fibrin and clot lysis were assessed in whole blood. ACS patients with impaired fibrinolysis were randomised 1:1:1 to clopidogrel 75 mg daily; clopidogrel 75 mg plus VLDR; or ticagrelor 90 mg twice daily, in addition to aspirin. At 30-days, there was no difference in lysis time between the groups, nor change from baseline. VLDR does not improve fibrinolysis at high or low shear. Further studies are needed to determine whether alternative antithrombotic regimens can enhance endogenous fibrinolysis.

Switching from Dual Antiplatelet Therapy with Aspirin Plus a P2Y12 Inhibitor to Dual Pathway Inhibition with Aspirin Plus Vascular-Dose Rivaroxaban: The Switching Anti-Platelet and Anti-Coagulant Therapy (SWAP-AC) Study

BACKGROUND

 To date, there are no data on switching to dual pathway inhibition (DPI) patients who have completed a guideline-recommended dual antiplatelet therapy (DAPT) regimen.

OBJECTIVES

 To assess the feasibility of switching from DAPT to DPI and to compare the pharmacodynamic (PD) profiles of these treatments.

METHODS

 This was a prospective, randomized, PD study conducted in 90 patients with chronic coronary syndrome (CCS) on DAPT with aspirin (81 mg/qd) plus a P2Y12 inhibitor (clopidogrel [75 mg/qd; n = 30], ticagrelor [90 mg/bid; n = 30], or prasugrel [10 mg/qd; n = 30]). Patients in each cohort were randomized to maintain DAPT or switch to DPI (aspirin 81 mg/qd plus rivaroxaban 2.5 mg/bid). PD assessments included: VerifyNow P2Y12 reaction units; light transmittance aggregometry following stimuli with adenosine diphosphate (ADP), tissue factor (TF), and a combination of collagen, ADP, and TF (maximum platelet aggregation %); thrombin generation (TG). Assays were performed at baseline and 30 days postrandomization.

RESULTS

 Switching from DAPT to DPI occurred without major side effects. DAPT was associated with enhanced P2Y12 inhibition, while DPI with reduced TG. Platelet-mediated global thrombogenicity (primary endpoint) showed no differences between DAPT and DPI in the ticagrelor (14.5% [0.0-63.0] vs. 20.0% [0.0-70.0]; p = 0.477) and prasugrel (20.0% [0.0-66.0] vs. 4.0% [0.0-70.0]; p = 0.482), but not clopidogrel (27.0% [0.0-68.0] vs. 53.0% [0.0-81.0]; p = 0.011), cohorts.

CONCLUSION

 In patients with CCS, switching from different DAPT regimens to DPI was feasible, showing enhanced P2Y12 inhibition with DAPT and reduced TG with DPI, with no differences in platelet-mediated global thrombogenicity between DPI and ticagrelor- and prasugrel-, but not clopidogrel-, based DAPT.

CLINICAL TRIAL REGISTRATION

 http://www.

CLINICALTRIALS

gov Unique Identifier: NCT04006288.

Platelet function testing in atrial fibrillation patients undergoing percutaneous coronary intervention

Platelet function testing (PFT) could be a useful clinical tool to guide individualized antithrombotic treatment in patients with atrial fibrillation (AF) undergoing percutaneous coronary intervention (PCI). We aimed to investigate platelet reactivity (PR) in the context of a contemporary registry. "Real-world" data were retrieved from a nationwide, multicenter, observational study of AF patients on oral anticoagulants (OAC) undergoing PCI. Patients treated with a P2Y₁₂ inhibitor, namely clopidogrel or ticagrelor, as part of double or triple antithrombotic therapy, were submitted to PFT before discharge and were followed up for 12 months. Out of 101 patients included in the study, 66 were submitted to PFT while on clopidogrel and 35 while on ticagrelor; PR was 162.9 ± 68 PRU and 46.02 ± 46 PRU, respectively (P < 0.001). High on-treatment PR (HTPR) was observed in 15 patients under clopidogrel (22.7%); 7 of them escalated to ticagrelor. Low on-treatment PR (LTPR) was found in 9 clopidogrel and 28 ticagrelor-treated patients (13.6% vs. 80%, P < 0.001), of whom only 1 de-escalated to clopidogrel. PR did not differ by OAC regimen. PFT results had no impact on aspirin prescription at discharge, while failed to predict significant bleeding events at follow up. Ticagrelor administration led to lower PR and lower incidence of HTPR in comparison with clopidogrel. Physicians' behavior in response to knowledge of a patient's PR was variable. Further studies are required to elucidate the role of PFT as a tool to guide individualized antithrombotic treatment in this clinical scenario.

Dual pathway inhibition in patients with atherosclerotic disease: pharmacodynamic considerations and clinical implications

INTRODUCTION

The persistence of elevated rates of ischemic recurrences despite the use of antiplatelet therapy among patients with atherosclerotic disease together with the understanding of the pivotal role of coagulation in the thrombo-inflammatory processes involved in the pathogenesis of atherosclerosis and its complications has fostered the development of treatments targeting both platelets and coagulation, a strategy known as dual-pathway inhibition (DPI).

AREAS COVERED

In this review we discuss the recent advancements in the understanding of the interplay between coagulation, platelets and inflammation involved in the pathophysiology of atherosclerosis and atherothrombosis, as the rationale for the implementation of a DPI strategy. We also discuss the available pharmacodynamic (PD) evidence and clinical implications with the use of DPI in patients with atherosclerotic disease.

EXPERT OPINION

The implementation of a DPI by adding the so-called 'vascular dose of rivaroxaban' (i.e. 2.5 mg bis in die), on top of antiplatelet therapy has consistently been associated with reduced levels of thrombin generation in PD studies and with reduced ischemic event rates at the cost of increased bleeding compared to antiplatelet therapy alone. Further research is warranted to best define patients in whom a DPI regimen has the best safety and efficacy profile.