Reversal Agents for Direct Oral Anticoagulants: Understanding New and Upcoming Options

Restarting Oral Anticoagulation in Patients With Atrial Fibrillation After an Intracranial Hemorrhage

Atrial fibrillation is the most common sustained cardiac arrhythmia in the general population. In western countries with aging populations, atrial fibrillation poses a significant health concern, as it is associated with a high risk of thromboembolism, stroke, congestive heart failure, and myocardial infarction. Thrombi are generated in the left atrial appendage, and subsequent embolism into the cerebral circulation is a major cause of ischemic stroke. Therefore, patients have a lifetime risk of stroke, and those at high risk, defined as a CHA2DS2-VASc2 (congestive heart failure, hypertension, age >75 years, diabetes mellitus, stroke/transient ischemic attack/thromboembolism, vascular disease, age 65-74 yrs, sex category) ≥2, are usually placed on oral anticoagulants. Unfortunately, long-term anticoagulation poses bleeding risks, of which intracranial hemorrhage (ICH) is the most feared and deadly complication.In patients who survive an ICH, the question of oral anticoagulation resumption arises. It is a therapeutic dilemma in which clinicians must decide how to manage the risk of thromboembolism versus recurrent hemorrhage. Although there is a substantial amount of retrospective data on the topic of resumption of anticoagulation, there are, at this time, no randomized controlled trials addressing the issue. We therefore sought to address ICH risk and management, summarize high quality existing evidence on restarting oral anticoagulation, and suggest an approach to clinical decision-making.

Laboratory measurement of apixaban using anti-factor Xa assays in acute ischemic stroke patients with non-valvular atrial fibrillation

Apixaban is effective and safe for preventing stroke, and its usage has increased exponentially in recent years. However, data concerning the therapeutic range of apixaban is limited. This study determined the trough and peak levels of apixaban-specific anti-factor Xa activity (AFXaA) in acute ischemic stroke patients with non-valvular atrial fibrillation (NVAF) in Korea. The study included 85 patients who received apixaban. Blood samples were taken to measure the trough and peak levels of AFXaA using a chromogenic anti-factor assay, as well as prothrombin time (PT) and activated partial thromboplastin time (aPTT). We also reviewed complications such as major bleeding of patients treated with apixaban. In patients given a 5.0-mg apixaban dose, the median trough and peak levels of AFXaA were 104.5 and 202.0 ng/mL. In patients given a 2.5-mg apixaban dose, the median trough and peak AFXaA levels were 76.0 and 151.0 ng/mL. The PT showed a positive correlation with increased AFXaA activity at both levels (Trough R = 0.486, Peak R = 0.592), but the aPTT had no relationship with AFXaA activity at both levels (Trough R = 0.181, Peak R = 0.129). Two cases with intracranial bleeding belonged to the highest AFXaA quartile (Trough, p = 0.176; Peak, p = 0.053). In conclusion, we determined the trough and peak levels of AFXaA in patients with NVAF while being treated with the apixaban in Korea. Our results could be used as a starting point when setting the reference ranges for laboratories using anti-Xa assay. Large-scale studies are needed to establish the reference range for AFXaA in patients with NVAF.

Periprocedural Management of Direct Oral Anticoagulants Surrounding Cardioversion and Invasive Electrophysiological Procedures

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As direct oral anticoagulants (DOACs) have demonstrated favorable efficacy and safety outcomes compared with vitamin K antagonists for the treatment and prevention of venous thromboembolism and the prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation, their role in the management of anticoagulation during electrophysiological procedures continues to evolve. At present, guidelines are limited regarding specific recommendations for the use of DOACs in these clinical settings. Here, we review available data regarding the risks and benefits associated with various periprocedural anticoagulation management approaches when patients receiving DOACs undergo electrophysiologic procedures including cardioversion, ablation, and device implantation. This discussion is intended to provide clinicians with an overview of available evidence and best practices to minimize the risk of both thromboembolic and bleeding events in the periprocedural setting.

Intravenous thrombolysis for acute ischaemic stroke in patients on direct oral anticoagulants

BACKGROUND AND PURPOSE

Whereas intravenous thrombolysis (IVT) is allowed for acute ischaemic stroke in patients on vitamin K antagonists with international normalized ratio ≤1.7, there are no similar recommendations for patients on direct oral anticoagulants (DOACs), notably due to the lack of coagulation tests to assess the therapeutic effects. Although the literature is scarce, consisting of small case series and retrospective studies, considering the frequency of this situation the French Vascular Neurology Society and the French Study Group on Haemostasis and Thrombosis have worked on a joint position paper to provide a practical position regarding the emergency management of ischaemic stroke in patients on DOACs.

METHOD

Based on a review of the literature, the authors wrote a first text that was submitted to a broad panel of members from the two societies. The text was then amended by the authors to address experts' comments and to reach a consensus.

RESULTS

In patients with normal renal function and who stopped the DOAC for at least 48 h, the management should not differ from that in patients without oral anticoagulant. In patients who are still on DOACs, mechanical thrombectomy is encouraged preferentially when applicable in first line. Otherwise, when specific tests are available, values <50 ng/ml indicate that IVT is allowed. In the absence of specific tests, standard tests (thrombin time, prothrombin time and activated partial thromboplastin time) can be used for dabigatran and rivaroxaban, although interpretation of these tests may be less reliable. In some patients on dabigatran, idarucizumab may be used before IVT.

CONCLUSIONS

In this expert opinion paper, it is suggested that IVT can be performed in patients selected according to the time elapsed since the drug was last taken, renal function, type of hospital where the patient is admitted and plasma concentration of DOAC.

Evaluation of bleeding in patients receiving direct oral anticoagulants

Direct oral anticoagulants (DOACs) are recognized by evidence-based treatment guidelines as the first-line option for the treatment of venous thromboembolism and prevention of stroke and systemic embolism in nonvalvular atrial fibrillation. As use of these anticoagulants has become favored over the past several years, reported bleeding-related adverse drug events with these agents has increased. In randomized clinical trials, all DOACs have a reduced risk for intracranial hemorrhage, while major and other bleeding results have varied among the agents compared to vitamin K antagonists. We have reviewed the bleeding incidence and severity from randomized and real-world data in patients receiving DOACs in an effort to provide the clinician with a critical review of bleeding and offer practical considerations for avoiding adverse events with these anticoagulants.

Coagulopathy Before and After Liver Transplantation: From the Hepatic to the Systemic Circulatory Systems

The hemostatic environment in patients with cirrhosis is a delicate balance between prohemostatic and antihemostatic factors. There is a lack of effective laboratory measures of the hemostatic system in patients with cirrhosis. Many are predisposed to pulmonary embolus, deep vein thrombosis, and portal vein thrombosis in the pretransplantation setting. This pretransplantation hypercoagulable milieu seems to extend for at least several months post-transplantation. Patients with nonalcoholic fatty liver disease, inherited thrombophilia, portal hypertension in the absence of cirrhosis, and hepatocellular carcinoma often require individualized approach to anticoagulation. Early reports suggest a potential role for low-molecular-weight heparins and direct-acting anticoagulants.