In vitro effects of recombinant activated factor VII on thrombin generation and coagulation following inhibition of platelet procoagulant activity by prasugrel

Association of Parenteral Anticoagulation Therapy With Outcomes in Non-ST-Segment Elevation Acute Coronary Syndrome Patients Without Invasive Therapy: Findings from the Improving Care for Cardiovascular Disease in China (CCC) project

Our previous study showed that parenteral anticoagulation therapy (PACT) in the context of aggressive antiplatelet therapy failed to improve clinical outcomes in patients undergoing percutaneous coronary intervention for non-ST-segment elevation acute coronary syndrome (NSTE-ACS). However, the role of PACT in patients managed medically remains unknown. This observational cohort study enrolled patients with NSTE-ACS receiving medical therapy from November 2014 to June 2017 in the Improving Care for Cardiovascular Disease in China-Acute Coronary Syndrome project. Eligible patients were included in the PACT group and non-PACT group. The primary outcomes were in-hospital all-cause mortality and major bleeding. The secondary outcome included minor bleeding. Among 23,726 patients, 8,845 eligible patients who received medical therapy were enrolled. After adjusting the potential confounders, PACT was not associated with a lower risk of in-hospital all-cause mortality (adjusted odds ratio (OR), 1.25; 95% confidence interval (CI), 0.92-1.71; P = 0.151). Additionally, PACT did not increase the incidence of major bleeding or minor bleeding (major bleeding: adjusted OR, 1.04; 95% CI, 0.80-1.35; P = 0.763; minor bleeding: adjusted OR, 1.27; 95% CI, 0.91-1.75; P = 0.156). The propensity score analysis confirmed the primary analyses. In patients with NSTE-ACS receiving antiplatelet therapy, PACT was not associated with a lower risk of in-hospital all-cause mortality or a higher bleeding risk in patients with NSTE-ACS receiving non-invasive therapies and concurrent antiplatelet strategies. Randomized clinical trials are warranted to reevaluate the safety and efficacy of PACT in all patients with NSTE-ACS who receive noninvasive therapies and current antithrombotic strategies.

[Management of the bleeding risk associated with antiplatelet agents]

Like all antithrombotic drugs, antiplatelet agents expose to a risk of bleeding complications. Clinical research has extensively focused on the efficacy of these drugs to reduce ischemic events. The bleeding risk associated with them was solely considered as an inevitable and acceptable complication. When two new potent P2Y12-receptor inhibitors, prasugrel and ticagrelor, were marketed, the risk of major bleeding increased. These new agents have modified the balance between the absolute risk reduction in ischemic events and the absolute risk increase in bleeding events. This paper is an update on the bleeding risk assessment associated with antiplatelet agents. It discusses the place of platelet function monitoring, and the optimal management of bleeding complications. It addresses the challenging issue of reversal of antiplatelet therapy, focusing especially on ticagrelor, which pharmacodynamics complicate bleeding management.

Applying the Cell-Based Coagulation Model in the Management of Critical Bleeding

The cell-based coagulation model was proposed 15 years ago, yet has not been applied commonly in the management of critical bleeding. Nevertheless, this alternative model may better explain the physiological basis of current coagulation management during critical bleeding. In this article we describe the limitations of the traditional coagulation protein cascade and standard coagulation tests, and explain the potential advantages of applying the cell-based model in current coagulation management strategies. The cell-based coagulation model builds on the traditional coagulation model and explains many recent clinical observations and research findings related to critical bleeding unexplained by the traditional model, including the encouraging results of using empirical 1:1:1 fresh frozen plasma:platelets:red blood cells transfusion strategy, and the use of viscoelastic and platelet function tests in patients with critical bleeding. From a practical perspective, applying the cell-based coagulation model also explains why new direct oral anticoagulants are effective systemic anticoagulants even without affecting activated partial thromboplastin time or the International Normalized Ratio in a dose-related fashion. The cell-based coagulation model represents the most cohesive scientific framework on which we can understand and manage coagulation during critical bleeding.

Ticagrelor reversal: in vitro assessment of four haemostatic agents

AIM

Management of ticagrelor-induced bleeding is challenging as platelet transfusion is ineffective. An effective strategy is needed. This study aimed to investigate in vitro the efficacy of four haemostatic drugs (HDs), namely recombinant activated factor VII (rFVIIa), fibrinogen concentrate (Fib), tranexamic acid (TXA) and factor XIII concentrate (FXIII) to improve the haemostatic capacity in the presence of ticagrelor.

METHODS

Blood was spiked with ticagrelor then supplemented by either HD or control. Several assays were performed: ADP-induced platelet aggregation measured by impedance aggregometry, light transmission and two global assays, thrombolastography with the platelet mapping device (TEG-PM) and a platelet-dependent thrombin generation assay (TGA).

RESULTS

Ticagrelor inhibited ADP-induced platelet aggregation and decreased the clot strength maximum amplitude (MA) in TEG-PM_ADP. None of the HDs corrected these parameters. However, rFVIIa shortened the coagulation time R using TEG-PM_thrombin and the time to peak prolonged by ticagrelor in TGA. Fib increased MA_thrombin and FXIII decreased LY30. TXA had no effects.

CONCLUSIONS

Whereas none of the HDs corrected ticagrelor-induced platelet inhibition, rFVIIa shortened coagulation times, Fib increased clot firmness and FXIII decreased fibrinolysis. Consequently, they may bypass ticagrelor effects by acting on fibrin formation or fibrinolysis. Further studies are needed to confirm these data in vivo.