DOACs - advances and limitations in real world

Statins as a preventative therapy for venous thromboembolism

The anti-inflammatory effects of statins have likely not been used to their fullest extent, particularly in reducing venous thromboembolic events. Current therapy for thrombotic events hinges on anticoagulation via heparin, warfarin or new oral anticoagulants. Interventional procedures with thrombectomy may also play a critical role. Unfortunately, thrombotic events can occur and recur despite meticulous anticoagulation therapy. Venous thromboembolism (VTE) includes both deep vein thrombosis (DVT) and pulmonary embolism (PE), two complicated and prevalent diseases that can cause chronic disease states such as post-thrombotic syndrome (PTS). In 2009 the JUPITER trial demonstrated that rosuvastatin may be effective when dealing with vascular inflammation by providing an anti-inflammatory effect. Multiple subsequent studies have looked at this association with some promising findings. The mechanism of action for statins is not entirely understood but there has been a variety of proposals and subsequent testing of inflammatory biomarkers. Additional prospective trials are needed to confirm the possible benefit of VTE reduction through an anti-inflammatory effect, but if this can be shown then statins may become a safe adjunctive therapy for VTE prevention.

An update on the bleeding risks associated with DOACs

The direct oral anticoagulants (DOACs), also referred to as novel (or non-vitamin K antagonist) oral anticoagulants (NOACs), represent a major development in anticoagulation therapy due to their rapid onset of action, predictable dose-response with fixed doses and limited interactions with food and drugs.^1,2 However, these agents have been in widespread clinical use for less than a decade and, compared with extensive experience with warfarin, there is uncertainty relating to optimal laboratory monitoring of anticoagulation, perioperative management and treatment of bleeding.3 In addition, there is currently only one drug licensed in the UK for rapid reversal of the anticoagulant effect of a DOAC. Here, we review DOAC-related bleeding and the role of drugs to reverse the anticoagulant action of DOACs.

The representativeness of direct oral anticoagulant clinical trials to hospitalized patients with atrial fibrillation

PURPOSE

Trials of the direct oral anticoagulants (DOACs) dabigatran, rivaroxaban and apixaban provide the basis for prescribing for the prevention of stroke and systemic embolism in atrial fibrillation (AF). The objective of this study was to assess the representativeness of the three pivotal DOAC randomized controlled trials of dabigatran, rivaroxaban and apixaban for unselected hospitalized patients with AF.

METHODS

A cross-sectional study was undertaken. All patients discharged with AF between 2012 and 2015 from a large public hospital network in Melbourne, Australia, were identified. Inclusion and exclusion criteria from the DOAC trials were applied. The proportions of hospitalized patients with AF who would have been eligible for the dabigatran (RE-LY), rivaroxaban (ROCKET-AF) and apixaban (ARISTOTLE) trials were estimated, as was pooled eligibility for all three trials. Characteristics of eligible and ineligible patients were compared.

RESULTS

For the 4734 patients, application of the inclusion and exclusion criteria resulted in 60.5, 52.6 and 35.8% eligibility for the trials of apixaban, dabigatran and rivaroxaban, respectively. Pooled eligibility across all three trials demonstrated that 33.4% of the patients would have been eligible for all three trials but 36.7% ineligible for any trial. Ineligible patients who met exclusion criteria were older and experienced more comorbidities.

CONCLUSIONS

The apixaban and dabigatran trials may be the most representative of hospitalized patients with AF. The DOAC trial results can readily be extrapolated to, and guide prescribing for, at least two thirds of patients discharged from a large metropolitan health service in Australia.

Exploring indications for the Use of direct oral anticoagulants and the associated risks of major bleeding

Thrombosis is a leading cause of morbidity and mortality in the United States. Arterial and venous thromboses are implicated in the pathogenesis of major disorders, including myocardial infarction, ischemic stroke, and venous thromboembolism. Over the past decade, direct oral anticoagulants (DOACs) (eg, direct thrombin inhibitor and factor Xa [FXa] inhibitors) have been adopted as alternatives to warfarin due to their clinical advantages and efficacy for the treatment of thrombosis. As with all anticoagulants, treatment with DOACs is associated with a risk of major bleeding, including life-threatening gastrointestinal bleeds and intracranial hemorrhages (ICHs). In turn, the burden of bleeding associated with DOAC treatment is itself associated with substantial healthcare costs that are amplified by an increased risk of thromboembolic events and mortality following major bleeding events, especially in patients with ICHs. Given the rapid adoption of the DOACs and projected usage in the large patient population affected by thromboembolic conditions, clinicians are increasingly likely to encounter patients with major bleeding events due to DOAC therapy. Unlike warfarin, effective strategies to manage these bleeds are limited. There is an unmet need for reversal agents for use in the management of patients who receive FXa inhibitors and experience life-threatening bleeding or need emergency surgery. Andexanet alfa and ciraparantag are being evaluated as potential antidotes for both direct and indirect FXa inhibitors.

Emerging Role of Direct Oral Anticoagulants in the Management of Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) and heparin-induced thrombocytopenia with thrombosis (HITT) are rare but potentially limb- and life-threatening complications of heparin therapy. Continuation of heparin or low-molecular-weight heparin is contraindicated due to platelet activation in the presence of (heparin-dependent) HIT antibodies. Primary treatment options currently include argatroban, fondaparinux, or bivalirudin. However, the parenteral administration routes and interference of argatroban with traditional coagulation markers complicate management. The goal of this review is to assess the viability of direct oral anticoagulants as an alternative treatment option in patients with HIT/HITT. Their use in HIT/HITT is reasonable, given absent cross-reactivity preformed with HIT antibodies. Furthermore, their rapid onset of action and induction of effective anticoagulation provide a favorable basis for their use in this condition. Herein, we summarize 3 studies and 8 case reports comprising 56 patients in whom direct oral anticoagulants were used in the treatment of HIT/HITT.