Meta-analysis of risk of stroke or transient ischemic attack with dabigatran for atrial fibrillation ablation

Dabigatran is a novel oral anticoagulant and may be useful during atrial fibrillation (AF) ablation for prevention of thromboembolic events. However, the benefits and adverse effects of periprocedural dabigatran therapy have not been thoroughly evaluated. A meta-analysis was performed to evaluate the efficacy and safety of dabigatran for anticoagulation in AF ablation. PubMed, The Cochrane Library, EMBASE, Web of Science, and CINAHL databases were searched from January 01, 2001 through July 30, 2013. Two reviewers reviewed the studies for inclusion and extracted data from studies comparing dabigatran with warfarin for AF ablation. A total of 5,513 patients undergoing catheter ablation were included in 17 observational studies and 1 randomized trial. Fourteen events of stroke or transient ischemic attacks were reported in the dabigatran group and 4 in the warfarin group (Peto's odds ratio 3.94, 95% confidence interval [CI] 1.54 to 10.08, number needed to harm=284 patients). The risk of all thromboembolic complications was also higher in the dabigatran group compared with the warfarin group (Peto's odds ratio 2.81, 95% CI 1.23 to 6.45). No major differences were observed for the risk of major bleeding (odds ratio 0.99, 95% CI 0.55 to 1.78), pericardial tamponade, and groin hematoma. A lower risk of minor bleeding was observed with dabigatran (odds ratio 0.60, 95% CI 0.41 to 0.87). In conclusion, periprocedural use of dabigatran for AF ablation was related to a higher risk of thromboembolic complications including stroke and transient ischemic attack.

The acute management of haemorrhage, surgery and overdose in patients receiving dabigatran

Dabigatran is an oral direct thrombin inhibitor (DTI) licensed for stroke prevention in atrial fibrillation and likely to be soon approved in Europe for treatment of venous thrombosis. Predictable pharmacokinetics and a reduced risk of intracranial haemorrhage do not negate the potential risk of haemorrhage. Unlike warfarin, there is no reversal agent and measurement of the anticoagulant effect is not 'routine'. The prothrombin time/international normalised ratio response to dabigatran is inconsistent and should not be measured when assessing a patient who is bleeding or needs emergency surgery. The activated partial thromboplastin time (APTT) provides a qualitative measurement of the anticoagulant effect of dabigatran. Knowledge of the time of last dose is important for interpretation of the APTT. Commercially available DTI assays provide a quantitative measurement of active dabigatran concentration in the plasma. If a patient receiving dabigatran presents with bleeding: omit/delay next dose of dabigatran; measure APTT and thrombin time (consider DTI assay if available); administer activated charcoal, with sorbitol, if within 2 h of dabigatran ingestion; give tranexamic acid (1 g intravenously if significant bleeding); maintain renal perfusion and urine output to aid dabigatran excretion. Dabigatran exhibits low protein binding and may be removed by dialysis. Supportive care should form the mainstay of treatment. If bleeding is life/limb threatening, consider an additional haemostatic agent. There is currently no evidence to support the choice of one haemostatic agent (FEIBA, recombinant factor VIIa, prothrombin complex concentrates) over another. Choice will depend on access to and experience with available haemostatic agent(s).

{blacktriangledown} Apixaban and {blacktriangledown} rivaroxaban for stroke prevention in AF

In October 2011, DTB reviewed the use of dabigatran, the first new oral anticoagulant licensed for the prevention of stroke and systemic embolism in adult patients with non-valvular atrial fibrillation (AF) and one or more defined risk factors.1 We noted that the potential advantages of dabigatran for many patients with AF and the continuing need to provide warfarin therapy for others, provided an important challenge for the NHS. The use of dabigatran has increased significantly in the UK and two other drugs have been licensed for this indication (▾apixaban-Eliquis, Bristol-Myers Squibb/Pfizer; ▾rivaroxaban-Xarelto, Bayer plc).2-6 In addition, published drug safety alerts have highlighted the risk of serious haemorrhage associated with the use of these drugs.7-9 Here we review the evidence for apixaban and rivaroxaban for the prevention of stroke and systemic embolism in adult patients with non-valvular atrial fibrillation.

[Laboratory assessment of haemostatic parameters in patients taking a direct thrombin inhibitor]

The problem of prevention and treatment of thromboembolic complications has a significant place in clinical practice for many years. The gold-standard agents in long-term protection from embologenic strokes, secondary prevention of venous thromboses and embolisms still remain vitamin K antagonists (in Russia - warfarin). However, despite high efficacy, administration of warfarin is fraught with dangers and associated with a series of inconveniences. A direct thrombin inhibitor, dabigatran etexilate (hereinafter referred to as dabigatran) was approved in the Russian Federation for prevention of thromboembolic complications in orthopaedic practice (2009), for prevention of ischaemic embologenic stroke in atrial fibrillation (2011) and for treatment of recurrent thrombosis of deep veins and pulmonary artery thromboembolism (2014). A characteristic feature of a therapeutic agent possessing an anticoagulation effect is correlation between intensity of hypocoagulation and haemorrhage. The effect of dabigatran on the laboratory parameters of haemostasis has been studied insufficiently, with no practical guidelines on assessing these alterations for prediction of the risk for haemorrhagic and thromboembolic complications. The present study included a total of 65 patients with non-valvular aetiology atrial fibrillation, taking dabigatran during from 6 to 18 months. All patients underwent laboratory assessment of the coagulation level and measuring blood coagulation activation markers in dynamics 10-14 days, 1, 6, 12 and 18 months after taking the agent. Thromboembolic and haemorrhagic risks were also assessed. It was revealed that administration of dabigatran leads to alterations in the main parameters of coagulogram. Determination of prothrombin (in % according to Quick's method) and activated partial thromboplastin time may be used for qualitative assessment of hypocoagulation. During the follow up period no statistically significant changes in the coagulation activation markers level were observed.

Wandering pneumonia caused by dabigatran

We herein describe the case of a 74-year-old man who experienced pulmonary consolidation and chest pain following administration of dabigatran, a novel oral anticoagulant. The consolidation settled spontaneously in another lung area, a condition sometimes referred to as "wandering pneumonia." Although we did not find specific pathological evidence of interstitial lung disease on transbronchial lung biopsy, a lung opacity spontaneously disappeared following discontinuance of dabigatran, and there was no recurrence. There are no other reports of dabigatran-induced lung injury, except alveolar hemorrhage and eosinophilic pneumonia. We should consider that any novel drug could cause various types of pulmonary injuries.

NOAC and intracerebral bleeding--presentation of four cases and review of the literature

AF might be a life threatening disease. Patients have been under oral antithrombotic treatment in order to avoid thrombotic events. Although this treatment proved to be effective in the last decades there was always the inconvenience of a regular blood control. In the last months NOACs have been flooding the market promising to be as effective as their older concurrents in certain circumstances and highlighting the fact that the control of INR has become obsolete. However, as there is no specific antidote up to date, NOACs might present a life threatening event in case of an intracerebral haemorrhage. The brain surgeons might find themselves in a difficult situation when they have to decide whether to operate on a patient with a compromised haemostasis or not. We present four patients who were treated with NOACs for AF. Three of them were admitted with intracerebral haemorrhage in our neurosurgical unit from January to October 2013. The fourth patient bled one week after stopping his treatment with NOAC. Furthermore we take a closer look to the existing literature and try to portray the issue from a neurosurgical point of view.

[Advantages and disadvantages of warfarin and pradaxa therapy for venous thromboembolism]

An analysis of complex examination of 110 patients with venous thromboembolism was made. The patients were separated into 2 groups. The first group included 60 patients, who had the start heparin therapy during 7 days with the following 6-month warfarin therapy. Warfarin was substituted by pradaxa (dabigatran) for 50 patients of the second group. The efficacy of pradaxa could be compared with warfarin. However, pradaxa had a number of advantages such as the predictable anticoagulant effect, standard dosages. This medicine is more predictable and doesn't require a control of homeostasis and an adjustment of drug dosage.

Meta-analysis of randomized controlled trials on risk of myocardial infarction from the use of oral direct thrombin inhibitors

Dabigatran has been associated with greater risk of myocardial infarction (MI) than warfarin. It is unknown whether the increased risk is unique to dabigatran, an adverse effect shared by other oral direct thrombin inhibitors (DTIs), or the result of a protective effect of warfarin against MI. To address these questions, we systematically searched MEDLINE and performed a meta-analysis on randomized trials that compared oral DTIs with warfarin for any indication with end point of MIs after randomization. We furthermore performed a secondary meta-analysis on atrial fibrillation stroke prevention trials with alternative anticoagulants compared with warfarin with end point of MIs after randomization. A total of 11 trials (39,357 patients) that compared warfarin to DTIs (dabigatran, ximelagatran, and AZD0837) were identified. In these trials, patients treated with oral DTIs were more likely to experience an MI than their counterparts treated with warfarin (285 of 23,333 vs 133 of 16,024, odds ratio 1.35, 95% confidence interval 1.10 to 1.66, p = 0.005). For secondary analysis, 8 studies (69,615 patients) were identified that compared warfarin with alternative anticoagulant including factor Xa inhibitors, DTIs, aspirin, and clopidogrel. There was no significant advantage in the rate of MIs with the use of warfarin versus comparators (odds ratio 1.06, 95% confidence interval 0.85 to 1.34, p = 0.59). In conclusion, our data suggest that oral DTIs were associated with increased risk of MI. This increased risk appears to be a class effect of these agents, not a specific phenomenon unique to dabigatran or protective effect of warfarin. These findings support the need for enhanced postmarket surveillance of oral DTIs and other novel agents.

[General characteristics of the new oral anticoagulants]

Treatment with vitamin K antagonists are subject to a common iatrogenic mainly characterized by hemorrhagic stroke. Their narrow therapeutic range associated with variability largely explains this phenomenon. New oral anticoagulants (NOAC) are now available. dabigatran (Pradaxa®) is a direct and specific thrombin inhibitor. It is excreted mainly by the kidney and is the only which can be dialyzed. Rivaroxaban (Xarelto®) and apixaban (Eliquis®) are factor X activated direct inhibitors. They are highly bound to plasma proteins and are metabolized mainly by the liver, via CYP3A4. All NOAC are substrates of P-glycoprotein (P-gp). Due to pharmacological changes, some populations at risk were identified: patients with hepatic impairment, renal impairment, elderly patients or low weight. Some pharmacokinetic or pharmacodynamic drug interactions alter the concentration and the expected impact of NOAC. The NOAC does not require biological monitoring. They interfere with the routine coagulation tests which should be interpreted with caution. Specific tests exist and can be used in case of emergencies. Currently, no antidote is available. The new oral anticoagulant look promising in the elderly. However, certain rules must be followed to reduce the risk of iatrogenic.

[Novel oral anticoagulants and atrial fibrillation in the elderly]

Atrial fibrillation treatment relies on anticoagulation therapy that reduces the risk of stroke. Vitamin K antagonists (VKA) were the only oral anticoagulant drugs for more than 50 years, but they are difficult to manage especially in the elderly. In France, VKA are the main cause of iatrogenic hospitalizations with about 17,000 hospitalizations per year and around 4,000 to 5,000 deaths per year. Pharmacologic properties of VKA, especially the narrow therapeutic margin explain the complexity of their management. Several studies have shown that patients treated with VKA were on average only 50% of the time with an INR in the therapeutic range. In other words, patients are, half of the time, either-under treated or over-treated. Within this framework, development of new oral anticoagulant drugs appeared necessary, in order to obtain drugs with larger therapeutic margin and a better risk/benefit profile than VKA. Three large randomized clinical trials including almost 50,000 patients with 20,000 subjects over 75 years old and 8,000 over 80 years old, show a better risk/benefit profile of the new oral anticoagulants (NOAC) than VKA, characterized by a 50% reduction of cerebral hemorrhages, 22% reduction of stroke and 12% reduction of total mortality. Meanwhile, their renal elimination and the lack of control of the biological efficacy need to be taken into account for their prescription. Renal failure (estimated glomerular filtration rate according to Cockcroft formula < 30 mL/min) contraindicates their use. Their half-life is shorter than that of VKA and the biological monitoring is not available, thus a good adherence to the treatment is important. Studies specifically conducted among geriatric older population with poly-pathologies and frail are therefore needed to evaluate tolerance of NOAC in real life conditions.

Management of dabigatran-induced bleeding: expert statement

The interdisciplinary group of experts has compiled a clinical guidance for manifest dabigatran-induced haemorrhage and envisaged invasive interventions on patients under dabigatran. It recommends an escalation of treatment measures as summarized in a pocket guide (see electronic supplementary material online and insert in the print issue).

Dabigatran versus warfarin in patients with mechanical heart valves

BACKGROUND

Dabigatran is an oral direct thrombin inhibitor that has been shown to be an effective alternative to warfarin in patients with atrial fibrillation. We evaluated the use of dabigatran in patients with mechanical heart valves.

METHODS

In this phase 2 dose-validation study, we studied two populations of patients: those who had undergone aortic- or mitral-valve replacement within the past 7 days and those who had undergone such replacement at least 3 months earlier. Patients were randomly assigned in a 2:1 ratio to receive either dabigatran or warfarin. The selection of the initial dabigatran dose (150, 220, or 300 mg twice daily) was based on kidney function. Doses were adjusted to obtain a trough plasma level of at least 50 ng per milliliter. The warfarin dose was adjusted to obtain an international normalized ratio of 2 to 3 or 2.5 to 3.5 on the basis of thromboembolic risk. The primary end point was the trough plasma level of dabigatran.

RESULTS

The trial was terminated prematurely after the enrollment of 252 patients because of an excess of thromboembolic and bleeding events among patients in the dabigatran group. In the as-treated analysis, dose adjustment or discontinuation of dabigatran was required in 52 of 162 patients (32%). Ischemic or unspecified stroke occurred in 9 patients (5%) in the dabigatran group and in no patients in the warfarin group; major bleeding occurred in 7 patients (4%) and 2 patients (2%), respectively. All patients with major bleeding had pericardial bleeding.

CONCLUSIONS

The use of dabigatran in patients with mechanical heart valves was associated with increased rates of thromboembolic and bleeding complications, as compared with warfarin, thus showing no benefit and an excess risk. (Funded by Boehringer Ingelheim; ClinicalTrials.gov numbers, NCT01452347 and NCT01505881.).

Higher persistence in newly diagnosed nonvalvular atrial fibrillation patients treated with dabigatran versus warfarin

BACKGROUND

Oral anticoagulation therapy is the primary tool in reducing stroke risk in patients with nonvalvular atrial fibrillation but is underused. Patients nonpersistent with therapy contribute to this underuse. The objective of this study was to compare persistence rates in newly diagnosed nonvalvular atrial fibrillation patients treated with warfarin versus dabigatran as their oral anticoagulation.

METHODS AND RESULTS

US Department of Defense administrative claims were used to identify patients receiving warfarin or dabigatran between October 28, 2010, and June 30, 2012. Patient records were examined for a minimum of 12 months before index date to restrict the analyses to those newly diagnosed with nonvalvular atrial fibrillation and naive-to-treatment, identifying 1775 on warfarin and 3370 on dabigatran. Propensity score matching was used to identify 1745 matched pairs. Persistence was defined as time on therapy to discontinuation. Kaplan-Meier curves were used to depict persistence over time. Cox proportional hazards model was used to determine the factors significantly associated with persistence. Using a 60-day permissible medication gap, the persistence rates were higher for dabigatran than for warfarin at both 6 months (72% versus 53%) and 1 year (63% versus 39%). Patients on dabigatran with a low-to-moderate risk of stroke (CHADS2<2) or with a higher bleed risk (HEMORR2HAGES>3) had a higher likelihood of nonpersistence (hazard ratios, 1.37; 95% confidence interval, 1.17-1.60; P<0.001; and hazard ratios, 1.24; 95% confidence interval, 1.04-1.47; P=0.016).

CONCLUSIONS

Patients who initiated dabigatran treatment were more persistent than patients who began warfarin treatment. Within each cohort, patients with lower stroke risk were more likely to discontinue therapy.