Approach to the new oral anticoagulants in family practice: part 1: comparing the options

OBJECTIVE

To compare key features of the new oral anticoagulants (NOACs)-dabigatran, rivaroxaban, and apixaban-and to address questions that arise when comparing the NOACs.

SOURCES OF INFORMATION

PubMed was searched for recent (January 2008 to week 32 of 2013) clinical studies relating to NOAC use for stroke prevention in atrial fibrillation (AF) and for the treatment of acute venous thromboembolism (VTE).

MAIN MESSAGE

All NOACs are at least as effective as warfarin for stroke prevention in patients with nonvalvular AF, and are at least as safe in terms of bleeding risk according to 3 large trials. Meta-analyses of these trials have shown that, compared with warfarin therapy, NOACs reduced total mortality, cardiovascular mortality, and intracranial bleeding, and there was a trend toward less overall bleeding. Practical advantages of NOACs over warfarin include fixed once- or twice-daily oral dosing without the need for coagulation monitoring, and few known or defined drug or food interactions. Potential drawbacks of NOACs include a risk of bleeding that might be increased in patients older than 75 years, increased major gastrointestinal bleeding with high-dose dabigatran, increased dyspepsia with dabigatran, the lack of a routine laboratory test to reliably measure anticoagulant effect, and the lack of an antidote for reversal. No direct comparisons of NOACs have been made in randomized controlled trials, and the choice of NOAC is influenced by individual patient characteristics, including risk of stroke or VTE, risk of bleeding, and comorbidity (eg, renal dysfunction).

CONCLUSION

The NOACs represent important alternatives in the management of patients with AF and VTE, especially for patients who have difficulty accessing regular coagulation monitoring. The companion to this article addresses common "what if" questions that arise in the long-term clinical follow-up and management of patients receiving NOACs.

Left atrial appendage thrombus with resulting stroke post-RF ablation for atrial fibrillation in a patient on dabigatran

Dabigatran etexilate is licensed for use in prevention of deep venous thromboembolism and in prevention of stroke and systemic embolism in nonvalvular atrial fibrillation (AF). It has also been used in patients for other indications as a substitute for warfarin therapy because it requires no monitoring; one group being patients undergoing radiofrequency (RF), ablation for AF, although there have been no consensus guidelines with regards to dosage and timing of dose. We report the case of a patient with documentary evidence of left atrial appendage (LAA) thrombus formation and neurological sequelae post-RF ablation despite being on dabigatran. This case highlights the concern that periprocedural dabigatran may not provide adequate protection from development of LAA thrombus and that a standardised protocol will need to be developed and undergo large multicentre trials before dabigatran can be safely used for patients undergoing RF-ablation.

[Extended options of anticoagulant treatment in thromboembolism]

Thromboembolic disease (TD) is a relatively common disease with acute risk of death and potential long-term consequences in term of postthrombotic syndrome or chronic pulmonary hypertension. Anticoagulant therapy is the basic therapeutic procedure; thrombolytic therapy and the introduction cava filter are appropriately indicated for individual cases. In past few years, new direct oral anticoagulant drugs (NOAC) have occurred - Xa factor or thrombin inhibitors which have demonstrated the same efficacy and even higher safety in comparison to conventional treatment. In mid 2014, 3 drugs of this group are registered in Czech Republic - rivaroxaban (Xarelto®), dabigatran (Pradaxa®) and apixaban (Eliquis®). These drugs have comparable efficacy and safety but they differ in schedule of dose administration. Rivaroxaban and apixaban can be administered immediately after diagnosis of venous thrombosis or hemodynamically stable pulmonary embolism. LMWH application has to precede few days the administration of dabigatran. Limitation of new drugs is their price. Unavailability of antidotes is temporary because current researches continue to find one for dabigatran and another for both of xabans. Duration of anticoagulant treatment after acute phase depends on the presence of thrombosis risk factors and the individual bleeding risk. Minimal duration of anticoagulant therapy is 3 months, commonly 6-12 months and in high risk patients it is "long term" treatment. Good results of new anticoagulant drugs in trials in term of thromboembolism recurrence prevention may change established habits in TD patients with long term treatment.

[Comparison of the safety of rivaroxaban versus dabigatran therapy in patients with persistent atrial fibrillation]

For 60 years, vitamin K antagonists have been used in prevention of thromboembolic complications in the course of atrial fibrillation (AF), however such therapy is associated with many inconveniences. New oral anticoagulants (NOAC), rivaroxaban and dabigatran, represent an attractive alternative to VKA.

THE AIM OF THE STUDY

Yo evaluate the safety of a 6-month therapy with rivaroxaban and dabigatran in patients (pts) with persistent AF.

MATERIALS AND METHODS

The analysis included 24 pts (14 females, 10 males) with nonvalvular AF and indications for oral anticoagulant therapy (CHA2DS2-VASc > or = 2, HAS-BLED < 3), hospitalized in the Clinic of Internal Diseases and Clinical Pharmacology of the Medical University of Lodz between July 2012 and September 2013. In the group of patients treated chronically with VKA, laboratory tests (GFR, creatinine, ALT AST, coagulation) were performed during their stay in the clinic. The patients were randomly assigned to the treatment with one of the new NOACs, rivaroxaban or dabigatran. After a 6-month period, the patients completed a questionnaire on their general health condition and follow-up laboratory tests were performed.

RESULTS

In the group of pts. receiving dabigatran INR increased by 23% (p = 0.0002) and APTT prolongation by 91% was noted (p = 0.0004) whereas in the group of pts receiving rivaroxaban an INR increase by 17% (p = 0.04) and APTT prolongation by 32% (p = 0.0043) were observed. After a 6-month therapy, dabigatran prolongs APTT significantly more, as compared to rivaroxaban (p=0.0002). Among patients using dabigatran, 16.7% experienced the following symptoms: abdominal pain, gastritis, nausea. 8.3% patients experienced bleeding from haemorrhoids, easier bruising. In the group of patients receiving rivaroxaban, 16.7% experienced the following symptoms: nosebleeds and easier bruising; 8.3%: bleeding from gums, haematuria. 25%: pruritus, rash: 8.3%. The hazard ratio (HR) for occurrence of dyspeptic symptoms was 1.13 for dabigatran. Minor bleeding is 3.6 times more common when using rivaroxaban.

CONCLUSIONS

Significant increase of INR and prolongation of APTT are observed after a 6-month therapy with rivaroxaban or dabigatran. Additionally, dabigatran significantly prolongs the prothrombin time. Despite the fact that dabigatran caused larger prolongation of APTT minor bleeding episodes occurred more frequently in patients treated with rivaroxaban. No worsening of kidney or liver function was observed during the 6-month therapy with rivaroxaban or dabigatran. Rywaroxaban more frequently causes minor bleeding, whereas treatment with dabigatran is associated with more frequent gastrointestinal adverse symptoms.

[Hemorrhagic stroke and new oral anticoagulants]

The recent release of new oral anticoagulants (NOAC) raises the question of the management of intracranial hemorrhage occurring during treatment with these molecules. Dabigatran, rivaroxaban and apixaban have different pharmacological characteristics that physicians need to know to adjust their prescription to each patient. Studies of efficacy and safety prior to the marketing of these molecules showed a decreased risk of intracranial hemorrhage compared with vitamin K antagonists. However, no reliable data are available regarding the prognosis of these hemorrhages occurring during NOAC treatment. In addition, there is no specific antidote and reversal protocol validated in humans. So, physicians are in a difficult situation when critical bleeding occurs. The timing of recovering normal hemostatic capacity is then a determinant factor of prognosis. Studies in animals or healthy volunteers showed a correction of the biological parameters using prothrombin complex concentrates activated or not, without reducing the volume of hematoma. On this basis, proposals have been issued by the french group of interest for perioperative hemostasis (GIHP) for the management of bleeding under NOAC treatment, which include management of intracranial hemorrhage.

Comparison of dabigatran and uninterrupted warfarin in patients with atrial fibrillation undergoing cardiac rhythm device implantations. Case-control study

BACKGROUND

The incidence of postoperative complications following pacemaker or implantable cardioverter-defibrillator implantations in patients treated with new oral anticoagulation agents has not been studied. Here we present a first comparison of complications after cardiac rhythm device (CRD) implantations in patients with atrial fibrillation (AF) treated with dabigatran or uninterrupted warfarin.

METHODS AND RESULTS

Using a case-control study design, we compared complications within 30 days after 236 CRD procedures performed under uninterrupted warfarin (n=118) or interrupted dabigatran (n=118).There were no significant differences in the baseline characteristics of both groups. In the warfarin group, 9 (8%) pocket hematomas were observed vs. 3 (3%) in the dabigatran group (P=0.075). Two complications in the warfarin group necessitated surgical intervention as opposed to none in the dabigatran group (P=0.156). The postprocedural blood loss expressed as a drop in hemoglobin was significantly greater in the warfarin group (-0.9±0.7 vs. -0.5±0.4 mmol/L, P=0.023). In the dabigatran group, 1 case of transient ischemic attack occurred. The mean time to hospital discharge was shorter in patients treated with dabigatran (2.5±2.3 vs. 3.8±4.1 days, P=0.02).

CONCLUSIONS

The incidence and severity of bleeding complications may be lower in patients treated with periprocedurally discontinued dabigatran when compared with uninterrupted warfarin therapy. Further evaluation of peri-interventional complications and establishment of an optimal anticoagulation management protocol are needed.

Evaluation of Trends of Inpatient Hospitalisation for Significant Haemorrhage in Patients Anticoagulated for Atrial Fibrillation before and after the Release of Novel Anticoagulants

Compared to Vitamin K antagonists (VKA), novel oral anticoagulants (NOACs) appear to be safer in terms of major bleeding risks with added advantage of having fixed dosing schedules when used in patients with non-valvular atrial fibrillation (AF). We sought to study the differences as sources and severity of anticoagulant-associated haemorrhage in patients with AF in the year preceding introduction of NOACs (first cohort) as compared to post approval of the NOACs (second cohort) by retrospectively reviewing the hospital admissions, as well as the pharmacodynamic and pharmacokinetic interactions between time periods. There were 359 patients for the first cohort and 405 patients for the second cohort, including 57 patients prescribed NOACs. There was no significant difference in age, deaths, source of bleeding, or rate of pharmacokinetic or pharmacodynamic interaction between the two time periods. Comparing all VKA patients to patients prescribed NOAC's, there were non-significant but higher rates of intracerebral bleed, significantly higher rates of pharmacokinetic (194 (25.4%) versus 0 (0%), p<.001) and similar rates of pharmacodynamic interactions (505 (66.1%) versus 39 (68.4%), p=.70). Drug-renal interactions were seen in 7 of the 57 (12.3%) NOAC-treated patients, in which all seven had acute renal failure that may have prolonged the effects of the anticoagulants. NOACs hold promise in that drug interactions are far less common than those seen in VKAs, and intracerebral bleeds appear to be less common in randomised trials as well as our review. For patients on dabigatran or rivaroxaban, consideration should be given to serial monitoring of renal function.

Management of hemorrhage with the target-specific oral anticoagulants

The target-specific oral anticoagulants have recently been introduced as alternatives to warfarin for both prophylactic and therapeutic indications. Although their efficacy and side-effect profiles have been favorable, there is significant concern about management of hemorrhage with these agents as there is no direct reversal agent available. It is important for clinicians to be aware of these agents and the issues that surround them. Most of the management of hemorrhage is based on expert opinion and case reviews. Given the potentially catastrophic consequences of acute hemorrhage while patients are on anticoagulation, specific treatments are needed. Some methods that have been described include activated charcoal, hemodialysis, prohemostatic agents, and transfusions. Target-specific therapies have been shown to be effective in early studies in animal models; however, the effects in humans are still under investigation. More investigation is needed on the management of bleeding complications from target-specific oral anticoagulants.

Intracranial hemorrhage mortality in atrial fibrillation patients treated with dabigatran or warfarin

BACKGROUND AND PURPOSE

In randomized trials, patients with atrial fibrillation (AF) receiving dabigatran, a direct oral anticoagulant, had lower risk of intracranial bleeding (ICB) than those on warfarin. However, concerns exist about potential worse outcomes in dabigatran users if bleeding occurs, given the lack of approved reversal agents. Thus, we examined in-hospital mortality in AF patients with ICB being treated with dabigatran versus warfarin in a real-world population in the United States.

METHODS

We analyzed healthcare utilization claims in the Truven Health Marketscan Research Databases. The study sample included patients with AF admitted to a hospital with a primary diagnosis of ICB. Information on medications, inpatient, and outpatient diagnoses was obtained from available claims. Propensity score-adjusted risk ratios and 95% confidence intervals of in-hospital mortality comparing current users of dabigatran versus warfarin were estimated using relative risk regression.

RESULTS

Among 2391 AF patients admitted with ICB (2290 on warfarin, 101 on dabigatran), 531 died during their admission. In-hospital mortality was similar in those treated with warfarin (22%) or dabigatran (20%). Compared with warfarin users, the propensity score-adjusted risk ratio (95% confidence interval) of mortality in dabigatran users was 0.93 (0.62-1.37). Associations were similar across different ICB subtypes (intracerebral hemorrhage, subarachnoid hemorrhage, and subdural hematoma).

CONCLUSIONS

In this sample of AF patients with ICB on oral anticoagulants, dabigatran was not associated with higher in-hospital mortality compared with warfarin. Hence, reluctance to use dabigatran because of a lack of approved reversal agents is not supported by our results.

Continuation of dabigatran therapy in "real-world" practice in Hong Kong

BACKGROUND

Dabigatran, an oral direct thrombin inhibitor, possesses several advantages over warfarin that can in principle simplify the management of stroke prevention in atrial fibrillation (AF). Nonetheless it remains unclear whether these advantages can translate to clinical practice and encourage long-term therapy. The objective was to describe long-term dabigatran therapy for stroke prevention in AF and to identify risk factors for discontinuation of therapy.

METHODS AND RESULTS

We studied 467 consecutive Chinese patients (72 ± 11 years, male: 53.8%) with a mean CHA2DS2-VASc score of 3.6 prescribed dabigatran for stroke prevention in AF from March 2010 to September 2013. Over a mean follow-up of 16 months, 101 patients (21.6%) permanently discontinued dabigatran. The mean time-to-discontinuation was 8 months. The most common reason for discontinuation was dyspepsia (30.7%), followed by other adverse events (17.8%) such as minor bleeding (8.9%), major gastrointestinal bleeding (7.9%), and intracranial hemorrhage (1%). Other reasons included dosing frequency (5.9%), fear of side effects (4.0%), lack of laboratory monitoring (1.0%), and cost (1.0%). Multivariable analysis revealed that low baseline estimated glomerular filtration rate (p = 0.02), absence of hypertension (p = 0.01), and prior use of a proton-pump inhibitor (p = 0.02) and H2-receptor blocker (p = 0.01) were independent predictors of drug discontinuation. In addition, there were altogether 9 ischemic strokes (1.5%/years), 3 intracranial hemorrhages (0.5%/year), and 24 major gastrointestinal bleedings (4.1%/year).

CONCLUSION

Dabigatran discontinuation is very common amongst Chinese AF patients. This reveals a management gap in the prevention of stroke in AF.

Dabigatran, rivaroxaban and apixaban for extended venous thromboembolism treatment: network meta-analysis

AIM

Many new oral anticoagulants (NOACs; dabigatran, rivaroxaban, and apixaban) are currently available to treat thromboembolic disease. There are no head-to-head trials comparing these agents. To assess the efficacy and safety of NOACs for prevention of recurrent venous thromboembolism (VTE), we performed a network meta-analysis.

METHODS

Medline, Embase, and the Cochrane-controlled trial register were searched, without language restriction, to identify trials. Studies were evaluated according to a priori inclusion criteria and appraised using established internal validity criteria. Adjusted indirect comparisons between agents were performed using well-established methods.

RESULTS

Three trials meeting inclusion criteria were identified. Direct comparison between apixaban 2.5 mg twice daily (BID) versus apixaban 5 mg BID showed no difference for any outcome. Clinically relevant non-major bleeding occurred less with both apixaban 2.5 mg BID (OR 0.23, 95% CI 0.08-0.62, P=0.004) and apixaban 5 mg BID [OR 0.31, 95% CI 0.11-0.82, P=0.019] compared to rivaroxaban 20 mg daily. Apixaban 2.5 mg BID showed less clinically relevant non-major bleeding than dabigatran 150 mg BID [OR 0.4, 95% CI 0.16-0.9, P=0.04], but not apixaban 5 mg BID. There were no differences between rivaroxaban 20 mg daily and dabigatran 150 mg BID. No differences in risk for recurrent VTE, major bleeding, or mortality were observed for any comparison between any pair of NOACs.

CONCLUSION

There were no significant differences in risk for recurrent VTE, major bleeding, or all-cause mortality between the NOACs. However, apixaban 2.5 mg BID was associated with less clinically significant non-major bleeding than either rivaroxaban 20 mg daily or dabigatran 150 mg BID.

Management of the bleeding patient receiving new oral anticoagulants: a role for prothrombin complex concentrates

Ease of dosing and simplicity of monitoring make new oral anticoagulants an attractive therapy in a growing range of clinical conditions. However, newer oral anticoagulants interact with the coagulation cascade in different ways than traditional warfarin therapy. Replacement of clotting factors will not reverse the effects of dabigatran, rivaroxaban, or apixaban. Currently, antidotes for these drugs are not widely available. Fortunately, withholding the anticoagulant and dialysis are freqnently effective treatments, particularly with rivaroxaban and dabigatran. Emergent bleeding, however, requires utilization of Prothrombin Complex Concentrates (PCCs). PCCs, in addition to recombinant factor VIIa, are used to activate the clotting system to reverse the effects of the new oral anticoagulants. In cases of refractory or emergent bleeding, the recommended factor concentrate in our protocols differs between the new oral anticoagulants. In patients taking dabigatran, we administer an activated PCC (aPCC) [FELBA] due to reported benefit in human in vitro studies. Based on human clinical trial evidence, the 4-factor PCC (Kcentra) is suggested for patients with refractory rivaroxaban- or apixaban-associated hemorrhage. If bleeding continues, recombinant factor VIIa may be employed. With all of these new procoagulant agents, the risk of thrombosis associated with administration of factor concentrates must be weighed against the relative risk of hemorrhage.

Dabigatran in secondary stroke prevention: clinical experience with 106 patients

INTRODUCTION

Our aim was to analyze our clinical experience with dabigatran etexilate in secondary stroke prevention.

METHODS

We retrospectively included patients starting dabigatran etexilate for secondary stroke prevention from March 2010 to December 2012. Efficacy and safety variables were registered.

RESULTS

106 patients were included, median follow-up of 12 months (range 1-31). Fifty-six females (52.8%), mean age 76.4 (range 50-95, SD 9.8), median CHADS2 4 (range 2-6), CHA2DS2-VASc 5 (range 2-9), and HAS-BLED 2 (range 1-5). Indication for dabigatran etexilate was ischemic stroke in 101 patients and acute cerebral hemorrhage (CH) due to warfarin in 5 (4.7%). Dabigatran etexilate 110 mg bid was prescribed in 71 cases (67%) and 150 mg bid was prescribed in the remaining. Seventeen patients (16%) suffered 20 complications during follow-up. Ischemic complications (10) were 6 transient ischemic attacks (TIA), 3 ischemic strokes, and 1 acute coronary syndrome. Hemorrhagic complications (10) were CH (1), gastrointestinal bleeding (6), mild hematuria (2), and mild metrorrhagia (1), leading to dabigatran etexilate discontinuation in 3 patients. Patients with previous CH remained uneventful. Three patients died (pneumonia, congestive heart failure, and acute cholecystitis) and 9 were lost during follow-up.

CONCLUSIONS

Dabigatran etexilate was safe and effective in secondary stroke prevention in clinical practice, including a small number of patients with previous history of CH.

Dabigatran: gastrointestinal ulcers

Dabigatran appears to provoke gastrointestinal ulcers that are all the more likely to bleed as it is an anticoagulant.

[Two cases of dabigatran-induced esophageal ulcer indicating the usefulness of drug administration guidance]

Here we report two cases of dabigatran-induced esophageal ulcer. Case 1 was a 67-year-old man who presented with heartburn that developed a month after dabigatran administration. Case 2 was an 81-year-old woman who presented with epigastralgia that developed within a few days of dabigatran administration. Endoscopic findings were similar in both cases, including shallow esophageal ulcers covered with a thin whitish membrane. The patients were advised to consume the drug with plenty of water during meals and to remain in a sitting position for 30 min after consumption. This method successfully decreased their symptoms and ulcers, indicating that drug administration guidance is extremely effective in managing dabigatran-induced esophageal injury.

Anticoagulation in atrial fibrillation

Atrial fibrillation increases the risk of stroke, which is a leading cause of death and disability worldwide. The use of oral anticoagulation in patients with atrial fibrillation at moderate or high risk of stroke, estimated by established criteria, improves outcomes. However, to ensure that the benefits exceed the risks of bleeding, appropriate patient selection is essential. Vitamin K antagonism has been the mainstay of treatment; however, newer drugs with novel mechanisms are also available. These novel oral anticoagulants (direct thrombin inhibitors and factor Xa inhibitors) obviate many of warfarin's shortcomings, and they have demonstrated safety and efficacy in large randomized trials of patients with non-valvular atrial fibrillation. However, the management of patients taking warfarin or novel agents remains a clinical challenge. There are several important considerations when selecting anticoagulant therapy for patients with atrial fibrillation. This review will discuss the rationale for anticoagulation in patients with atrial fibrillation; risk stratification for treatment; available agents; the appropriate implementation of these agents; and additional, specific clinical considerations for treatment.