A case of dabigatran-associated acute renal failure

Dabigatran is a direct thrombin inhibitor that reduces the risk of systemic embolism in patients with nonvalvular atrial fibrillation. We report a case of an elderly man who developed unexplained rapid decline in renal function 6 weeks after starting dabigatran. A renal biopsy was planned to find out the etiology of acute renal failure, but the patient has significantly prolonged coagulation parameters despite holding medication for 5 days per manufacturer's recommendation. He was started on hemodialysis due to worsening renal function and to ensure dabigatran clearance before renal biopsy. Renal biopsy showed renal atheroembolic disease, which was possibly induced by dabigatran. Although renal atheroembolic disease is a known rare complication following treatment with warfarin, heparin, and thrombolytic agents, this is the first reported case of renal atheroembolic disease potentially caused by dabigatran. This case also highlights the extended duration of prolonged coagulation parameters after holding dabigatran and its implication for timing of nonemergent invasive procedures.

Effect of dabigatran on referrals to and switching from warfarin in two academic anticoagulation management services

Dabigatran was expected to replace warfarin for stroke prevention in patients with nonvalvular atrial fibrillation (AF) who are warfarin naive, difficult to maintain in therapeutic range, or at risk of warfarin-related bleeding complications. We hypothesized that the number of patients with nonvalvular AF referred to Anticoagulation Management Services would decrease sharply and that most would switch from warfarin to dabigatran. We evaluated the number of patients with nonvalvular AF referred to 2 large services, Anticoagulation Management Service 1 and Anticoagulation Management Service 2, 12 months before and after market entry of dabigatran. We also evaluated the number of patients who switched from warfarin to dabigatran. Anticoagulation Management Service 1 follows 1,225 patients with nonvalvular AF with mean CHADS₂ and CHA₂DS₂-VASc scores of 2.0 and 3.5, respectively. Anticoagulation Management Service 2 follows 1,137 patients with nonvalvular AF with mean CHADS₂ and CHA₂DS₂-VASc scores of 2.0 and 3.3, respectively. In the 12 months preceding market entry of dabigatran, patients with nonvalvular AF constituted 537 (31.4%) of the referrals sent to Anticoagulation Management Service 1 and increased to 793 (32.3%) in the following 12 months. For Anticoagulation Management Service 2, patients with nonvalvular AF constituted 617 (30.7%) of referrals before market entry of dabigatran and decreased to 495 (25.2%) of referrals. Eighty-one patients (6.6%) from Anticoagulation Management Service 1 and 44 (3.9%) from Anticoagulation Management Service 2 have switched from warfarin to dabigatran. The frequency of initial prescription of dabigatran for stroke prevention in AF and the frequency of transition from warfarin to dabigatran have been less than expected.

Adherence to anticoagulant treatment with dabigatran in a real-world setting

BACKGROUND

In clinical trials, adherence to a prescribed regimen with dabigatran was enhanced by frequent follow-up visits and pill counts.

OBJECTIVES

To describe the experience of dabigatran treatment in clinical practice, focusing on adherence.

PATIENTS/METHODS

In a cross-sectional cohort study, we interviewed 103 patients treated for at least 3 months with dabigatran and followed by our anticoagulant clinic. We obtained information on the number of capsules of dabigatran dispensed by the pharmacy of each patient covering the entire treatment period and calculated the adherence. In addition, information on the frequency of missed capsules, bleeding, thromboembolic events and other adverse events, specifically dyspepsia, was captured from the interviews and medical records.

RESULTS

The mean age was 75.5 (± 8.5) years, 46% were females, and the mean CHADS2 score was 2.5. Dispensation data were obtained for 99 patients and adherence was 99.7% (median; interquartile range 94.6%-100%) with 11 patients showing < 80% adherence. During their interview, 31 patients (30%) acknowledged that they sometimes had missed taking the medication, ranging from 'twice in 6 years' to 'every day'. One additional patient with adherence < 80% was identified. Twenty-one patients (20%) reported bleeding complications, two of which were major; one patient had an ischemic stroke and 34 (33%) reported some degree of dyspepsia. There were no significant differences in the results between RE-LY study-experienced and study-naïve patients.

CONCLUSION

In our clinical practice adherence to the twice-daily dabigatran regimen was generally good, although 12% of the patients had an inadequate adherence. Routine feedback from the pharmacies could inform the physician to improve the anticoagulant management.

Is dabigatran considered a cost-effective alternative to warfarin treatment: a review of current economic evaluations worldwide

OBJECTIVE

Dabigatran was the first of a new generation of anticoagulation drugs for the indication of non-valvular atrial fibrillation (AF) to be approved. Evidence show that dabigatran 150 mg twice daily significantly reduces the risk of stroke and systemic embolism (RR = 0.65; p < 0.001) and shows a comparable rate of major bleedings (RR = 0.93; p = 0.32), whereas dabigatran 110 mg twice daily was associated with a comparable rate of stroke and systemic embolism (RR = 0.90; p = 0.30) and a significantly lower rate of major bleedings compared to warfarin treatment (RR = 0.80; p = 0.003). The purpose is to review current economic evaluations of these alternatives for healthcare professionals to include these findings in their decision-making.

METHODS

A systematic literature search identified 43 economic evaluations, of which 10 were included and evaluated according to the Consensus Health Economic Criteria list (CHEC-list) and the Oxford model.

RESULTS

Six economic evaluations concluded that dabigatran was a cost-effective alternative to warfarin. One evaluation concluded the same except when quality in warfarin treatment was excellent, with a mean time in therapeutic range (TTR) > 73%. Three evaluations concluded that dabigatran was a cost-effective alternative to warfarin in patient sub-groups; TTR ≤ 64%, congestive heart failure, hypertension, age ≥ 75, diabetes mellitus, prior stroke or transient ischemic attack (CHADS2 score) ≥3, or a CHADS2 score = 2 unless international normalized ratio (INR) control was excellent, and with high risk of stroke or in a low-quality warfarin treatment. Dabigatran 110 mg twice daily was in general dominated by dabigatran 150 mg twice daily.

LIMITATIONS

The evaluations were not fully homogeneous, as some did not include loss of productivity, costs of dyspepsia, and annual costs of dabigatran patient management.

CONCLUSIONS

In the majority of the economic evaluations, dabigatran is a cost-effective alternative to warfarin treatment. In some evaluations dabigatran is only cost-effective in sub-groups, such as patients with a low TTR-value in warfarin treatment and a CHADS2 score ≥2.

Potential impact of new oral anticoagulants on the management of atrial fibrillation-related stroke in primary care

AIM

Anticoagulant prophylaxis with vitamin K antagonists (such as warfarin) is effective in reducing the risk of stroke in patients with atrial fibrillation (AF). New oral anticoagulants have emerged as potential alternatives to traditional oral agents. The purpose of this review was to summarise the effectiveness and safety of rivaroxaban, dabigatran and apixaban in stroke prevention in patients with AF in phase III trials, evaluate their cost-effectiveness and consider the implications for primary care.

METHODOLOGY

A literature search was performed between 2007 and 2012, selecting all phase III trials (ROCKET AF, RE-LY and ARISTOTLE) of new oral anticoagulants and relevant cost-benefit studies.

RESULTS

Evidence shows that all three agents are at least as effective as warfarin in the prevention of stroke and systemic emboli, with similar safety profiles. Cost-benefit studies of rivaroxaban and dabigatran further confirm their potential use as alternatives to warfarin in clinical practice. These observations may allow stratification of the general practice AF population, to help prioritise which patients may benefit from receiving a new oral anticoagulant.

CONCLUSION

The clinical and economic benefits of the new oral anticoagulants, along with appropriate risk stratification, may enable a higher number of patients with AF to receive effective and convenient prophylaxis for stroke prevention.

Clinical review: Clinical management of new oral anticoagulants: a structured review with emphasis on the reversal of bleeding complications

New oral anticoagulants, including dabigatran, rivaroxaban, and apixaban, have been recently approved for primary and secondary prophylaxis of thromboembolic conditions. However, there is no clear strategy for managing and reversing their anticoagulant effects. We aimed to summarize the available evidence for clinical management and reversal of bleeding associated with new oral anticoagulants. Using a systematic review approach, we aimed to identify studies describing reversal strategies for dabigatran, rivaroxaban, and apixaban. The search was conducted using Medline, EMBASE, HealthSTAR, and grey literature. We included laboratory and human studies. We included 23 studies reported in 37 out of 106 potentially relevant references. Four studies were conducted in humans and the rest were in vitro and in vivo studies. The majority of the studies evaluated the use of prothrombinase complex concentrate (PCC), either activated or inactivated, and recombinant activated factor VII (rFVIIa). Other interventions were also identified. Laboratory studies suggest that hemostatic parameters and bleeding might be partially or completely corrected by PCC for rivaroxaban better than dabigatran. Studies in humans suggest that PCC might reverse the effects of rivaroxaban better than dabigatran assessed by hemostatic tests. We were not able to locate studies evaluating the clinical efficacy of these agents. The best available evidence suggests that PCC (activated or inactivated) might be the best option for reversing new anticoagulants. Evidence for rFVIIa is less compelling. There might be differences in the efficacy of reversing agents for different anticoagulants. Studies assessing the clinical efficacy of these reversal agents are urgently needed.

Bleeding with dabigatran, rivaroxaban, apixaban. No antidote, and little clinical experience

Dabigatran, rivaroxaban and apixaban are oral anticoagulants used to prevent or treat thrombosis in a variety of situations. Like all anticoagulants, these drugs can provoke bleeding. How should patients be managed if bleeding occurs during dabigatran, rivaroxaban or apixaban therapy? How can the risk of bleeding be reduced in patients who require surgery or other invasive procedures? To answer these questions, we reviewed the available literature, using the standard Prescrire methodology. In clinical trials, warfarin, enoxaparin, dabigatran, rivaroxaban and apixaban were associated with a similar frequency of severe bleeding. Numerous reports of severe bleeding associated with dabigatran have been recorded since this drug was first marketed. Some situations are associated with a particularly high bleeding risk, including: even mild renal failure, advanced age, extremes in body weight and drug-drug interactions, particularly with antiplatelet agents (including aspirin), nonsteroidal antiinflammatory drugs, and many drugs used in cardiovascular indications. In patients treated with dabigatran, rivaroxaban or apixaban, changes in the INR (international normalised ratio) and activated partial thromboplastin time (aPTT) do not correlate with the dose. In early 2013, there is still no routine coagulation test suitable for monitoring these patients; specific tests are only available in specialised laboratories. In early 2013 there is no antidote for dabigatran, rivaroxaban or apixaban, nor any specific treatment with proven efficacy for severe bleeding linked to these drugs. Recommendations on the management of bleeding in this setting are based mainly on pharmacological parameters and on scarce experimen-Haemodialysis reduces the plasma concentration of dabigatran, while rivaroxaban and apixaban cannot be eliminated by dialysis. Prothrombin complex concentrates and recombinant activated factor VII seem to have little or no efficacy, and they carry a poorly documented risk of thrombosis. For patients undergoing surgery or other invasive procedures, clinical practice guidelines are primarily based on pharmacokinetic parameters and on extrapolation of data on vitamin K antagonists. The decision on whether or not to discontinue anticoagulation before the procedure mainly depends on the likely risk of bleeding. In patients at high risk of thrombosis, heparin can be proposed when the anticoagulant is withdrawn. In early 2013, difficulties in the management of bleeding and of situations in which there is a risk of bleeding weigh heavily in the balance of potential harm versus potential benefit of dabigatran, rivaroxaban and apixaban. When an oral anticoagulant is required, it is best to choose warfarin, a vitamin K antagonist, and the drug with which we have the most experience, except in those rare situations in which the INR cannot be maintained within the therapeutic range.

Use of dabigatran for periprocedural anticoagulation in patients undergoing catheter ablation for atrial fibrillation

BACKGROUND

Pulmonary vein isolation (PVI) for atrial fibrillation is associated with a transient increased risk of thromboembolic and hemorrhagic events. We hypothesized that dabigatran can be safely used as an alternative to continuous warfarin for the periprocedural anticoagulation in PVI.

METHODS AND RESULTS

A total of 999 consecutive patients undergoing PVI were included; 376 patients were on dabigatran (150 mg), and 623 patients were on warfarin with therapeutic international normalized ratio. [corrected] Dabigatran was held 1 to 2 doses before PVI and restarted at the conclusion of the procedure or as soon as patients were transferred to the nursing floor. Propensity score matching was applied to generate a cohort of 344 patients in each group with balanced baseline data. Total hemorrhagic and thromboembolic complications were similar in both groups, before (3.2% versus 3.9%; P=0.59) and after (3.2% versus 4.1%; P=0.53) matching. Major hemorrhage occurred in 1.1% versus 1.6% (P=0.48) before and 1.2% versus 1.5% (P=0.74) after matching in the dabigatran versus warfarin group, respectively. A single thromboembolic event occurred in each of the dabigatran and warfarin groups. Despite higher doses of intraprocedural heparin, the mean activated clotting time was significantly lower in patients who held dabigatran for 1 or 2 doses than those on warfarin.

CONCLUSIONS

Our study found no evidence to suggest a higher risk of thromboembolic or hemorrhagic complications with use of dabigatran for periprocedural anticoagulation in patients undergoing PVI compared with uninterrupted warfarin therapy.

[Effective, safe stroke prevention with novel oral anticoagulants in patients with atrial fibrillation. Focus on dabigatran]

Non-valvular AF is the most common cardiac arrhytmia. Its incidence increases with age. AF is an independent risk factor for ischaemic stroke, representing a five times higher risk for it, associated with a high mortality rate. Beside AF, there are several other risk factors which influence the risk of stroke. Stroke risk calculator can be used to assess the risk of patient having a stroke. The most endangered group of patients with AF are those who have already suffered from cerebrovascular event. The only effective medication for prevention of stroke due to AF had been the application of vitamin K antagonists (VKA) which considerably decrease the rate of ischaemic event in a patient with AF providing that the INR is in the therapeutic range. VKA have several limitations of use in clinical practice and the fear of bleeding complications results an underusing of these drugs. Only 50% of all patients treated with VKA reaches the therapeutic range of INR. The breakthrough of prevention of stroke in recent years is undisputedly the coming out of novel oral anticoagulants (NOACs, thrombin and Xa-factor inhibitors). Recent studies suggest that these novel drugs prove the same efficacy as VKA drugs, furthermore dabigatran in a dose of 2 x 150 mg or apixaban in 2 x 5 mg was statistically superior to warfarin in the prevention of stroke. NOACs have shown a large reduction in intracranial hemorrhage compared with warfarin. They are given as a fixed dose and do not require persistent monitoring making them much more convenient. NOACs at guidelines of European Society of Cardiology act as a preferable drugs in case of ischaemic stroke with AF Probably the extended use of NOACs in clinical practice will be the mainstream of stroke prevention in the future.

The new oral anticoagulants in clinical practice

Vitamin K antagonists were the only class of oral anticoagulants available to clinicians for decades. However, with the US Food and Drug Administration approval of new oral anticoagulants, such as dabigatran, rivaroxaban, and apixaban, clinicians now have a broader choice. Given the recent approval and availability of these medications, several questions arise while deciding which of them would be best suited for a particular patient. This article provides a concise review for clinicians entailing the main studies that evaluated the efficacy and safety of these drugs, their pharmacokinetic and pharmacodynamic properties, and a practical approach to their clinical use. For this review, we conducted searches of PubMed and MEDLINE for articles published between January 1, 2000, and January 30, 2013, using the following search terms: oral anticoagulants, dabigatran, apixaban, rivaroxaban, novel anticoagulants, bleeding complications, management of bleeding complications, pharmacodynamics, and pharmacokinetics. Studies published in English were selected for inclusion in this review, as were additional articles identified from bibliographies.

Reversal of oral anticoagulation

Although the use of dabigatran and rivaroxaban are increasing, data on the reversal of their effects are limited. The lack of reliable monitoring methods and specific reversal agents renders treatment strategies empirical, and as a result, treatment consists mainly of supportive measures. Therefore, we performed a systematic search of the PubMed database to find studies and reviews pertaining to oral anticoagulation reversal strategies. This review discusses current anticoagulation reversal recommendations for the oral anticoagulants warfarin, dabigatran, and rivaroxaban for patients at a heightened risk of bleeding, actively bleeding, or those in need of preprocedural anticoagulation reversal. We highlight the literature that shaped these recommendations and provide directions for future research to address knowledge gaps. Although reliable recommendations are available for anticoagulation reversal in patients treated with warfarin, guidance on the reversal of dabigatran and rivaroxaban is varied and equivocal. Given the increasing use of the newer agents, focused research is needed to identify effective reversal strategies and develop and implement an accurate method (assay) to guide reversal of the newer agents. Determining patient-specific factors that influence the effectiveness of reversal treatments and comparing the effectiveness of various treatment strategies are pertinent areas for future anticoagulation reversal research.

[Recommendations on use of direct oral anticoagulants in the perioperative period]

Because of the characteristics of direct oral anticoagulants (DOA), the lack of an antidote to completely reverse their anticoagulant effects, the absence of standardization in monitoring of their effects, and limited experience of their use, specific recommendations for their management in the perioperative period or in emergencies are required. In elective surgery, in patients with normal renal function and low hemorrhagic/ thrombotic risk, DOA should be withdrawn 2 days before the intervention; when the hemorrhagic/ thrombotic risk is higher, bridge therapy with a low molecular weight hepatin beginning 5 days before the intervention is proposed as an alternative. In emergency surgery, systematic administration of hemostatic drugs as prophylaxis is not recommended. In DOA-related acute hemorrhage, administration of prothrombin complex concentrate, fresh plasma or factor VIIa should be evaluated, and general measures to control bleeding should be implemented.

Dabigatran overdose secondary to acute kidney injury and amiodarone use

Oral direct thrombin inhibitors have improved treatment of non-valvular atrial fibrillation. Safety concerns have been raised since there is no antidote for treatment of secondary haemorrhages and the absence of widely validated test to monitor drug levels. We present a case of dabigatran overdose in an 82-year-old female who was treated with a seemingly appropriate dose.

Extended use of dabigatran, warfarin, or placebo in venous thromboembolism

BACKGROUND

Dabigatran, which is administered in a fixed dose and does not require laboratory monitoring, may be suitable for extended treatment of venous thromboembolism.

METHODS

In two double-blind, randomized trials, we compared dabigatran at a dose of 150 mg twice daily with warfarin (active-control study) or with placebo (placebo-control study) in patients with venous thromboembolism who had completed at least 3 initial months of therapy.

RESULTS

In the active-control study, recurrent venous thromboembolism occurred in 26 of 1430 patients in the dabigatran group (1.8%) and 18 of 1426 patients in the warfarin group (1.3%) (hazard ratio with dabigatran, 1.44; 95% confidence interval [CI], 0.78 to 2.64; P=0.01 for noninferiority). Major bleeding occurred in 13 patients in the dabigatran group (0.9%) and 25 patients in the warfarin group (1.8%) (hazard ratio, 0.52; 95% CI, 0.27 to 1.02). Major or clinically relevant bleeding was less frequent with dabigatran (hazard ratio, 0.54; 95% CI, 0.41 to 0.71). Acute coronary syndromes occurred in 13 patients in the dabigatran group (0.9%) and 3 patients in the warfarin group (0.2%) (P=0.02). In the placebo-control study, recurrent venous thromboembolism occurred in 3 of 681 patients in the dabigatran group (0.4%) and 37 of 662 patients in the placebo group (5.6%) (hazard ratio, 0.08; 95% CI, 0.02 to 0.25; P<0.001). Major bleeding occurred in 2 patients in the dabigatran group (0.3%) and 0 patients in the placebo group. Major or clinically relevant bleeding occurred in 36 patients in the dabigatran group (5.3%) and 12 patients in the placebo group (1.8%) (hazard ratio, 2.92; 95% CI, 1.52 to 5.60). Acute coronary syndromes occurred in 1 patient each in the dabigatran and placebo groups.

CONCLUSIONS

Dabigatran was effective in the extended treatment of venous thromboembolism and carried a lower risk of major or clinically relevant bleeding than warfarin but a higher risk than placebo. (Funded by Boehringer Ingelheim; RE-MEDY and RE-SONATE ClinicalTrials.gov numbers, NCT00329238 and NCT00558259, respectively.).