Integrating new approaches to atrial fibrillation management: the 6th AFNET/EHRA Consensus Conference.

There are major challenges ahead for clinicians treating patients with atrial fibrillation (AF). The population with AF is expected to expand considerably and yet, apart from anticoagulation, therapies used in AF have not been shown to consistently impact on mortality or reduce adverse cardiovascular events. New approaches to AF management, including the use of novel technologies and structured, integrated care, have the potential to enhance clinical phenotyping or result in better treatment selection and stratified therapy. Here, we report the outcomes of the 6th Consensus Conference of the Atrial Fibrillation Network (AFNET) and the European Heart Rhythm Association (EHRA), held at the European Society of Cardiology Heart House in Sophia Antipolis, France, 17-19 January 2017. Sixty-two global specialists in AF and 13 industry partners met to develop innovative solutions based on new approaches to screening and diagnosis, enhancing integration of AF care, developing clinical pathways for treating complex patients, improving stroke prevention strategies, and better patient selection for heart rate and rhythm control. Ultimately, these approaches can lead to better outcomes for patients with AF.

Net clinical benefit of dabigatran vs. warfarin in venous thromboembolism: analyses from RE-COVER®, RE-COVER™ II, and RE-MEDY™.

The direct oral anticoagulants, e.g., dabigatran etexilate (DE), are effective and well tolerated treatments for venous thromboembolism (VTE). Net clinical benefit (NCB) is a useful concept in weighing potential benefits against potential harm of comparator drugs. The NCB of DE vs. warfarin in VTE treatment was compared. Post-hoc analyses were performed on pooled data from the 6-month RE-COVER® and RE-COVER™ II trials, and data from the RE-MEDY™ trial (up to 36 months), to compare the NCB of DE (150 mg twice daily) and warfarin [target international normalized ratio (INR) 2.0-3.0]. Patients (≥18 years old) had symptomatic proximal deep vein thrombosis and/or pulmonary embolism. NCB was the composite of cardiovascular endpoints (non-fatal events of recurrent VTE, myocardial infarction, stroke or systemic embolism), all-cause death, and bleeding outcomes, all weighted equally. A broad definition of NCB included major bleeding events (MBE) and clinically relevant non-major bleeding events as bleeding outcomes, while a narrow definition included just MBE. The pooled dataset totalled 5107 patients from RE-COVER/RE-COVER II and 2856 patients from RE-MEDY. When NCB was narrowly defined, NCB was similar between DE and warfarin. When broadly defined, NCB was superior with DE vs. warfarin [RE-COVER/RE-COVER II, hazard ratio (HR) 0.80; 95% confidence interval (CI), 0.68-0.95 and RE-MEDY, HR 0.73; 95% CI 0.59-0.91]. These findings were unaffected by warfarin time in therapeutic range. The NCB of DE was similar or superior to warfarin, depending on the NCB definition used, regardless of the quality of INR control.

Efficacy of dabigatran versus warfarin in patients with acute venous thromboembolism in the presence of thrombophilia: Findings from RE-COVER®, RE-COVER™ II, and RE-MEDY™.

It is unclear whether thrombophilia causes resistance to anticoagulant therapy. Post hoc analyses of data from RE-COVER®, RE-COVER™ II, and RE-MEDY™ were performed to compare dabigatran etexilate with warfarin for the treatment and prevention of venous thromboembolism (VTE) in patients with thrombophilia or antiphospholipid antibody syndrome (APS). There were no significant differences in symptomatic VTE/VTE-related deaths between dabigatran etexilate and warfarin in patients with or without thrombophilia. All bleeding event categories were less frequent with dabigatran etexilate than with warfarin, regardless of whether patients had thrombophilia, no thrombophilia, or were not tested. However, these differences did not reach significance in every group. In patients with APS, there was no significant difference in VTE/VTE-related deaths between the two treatment arms. Rates of bleeding events tended to be lower with dabigatran etexilate than with warfarin, reaching statistical significance for any bleeding event. In conclusion, the efficacy and safety of dabigatran etexilate were not significantly affected by the presence of thrombophilia or APS. ClinicalTrials.gov RECOVER IDENTIFIER NCT00291330; RECOVER II IDENTIFIER NCT00680186; RE-MEDY IDENTIFIER NCT00329238.

Dabigatran etexilate for thromboprophylaxis in over 5000 hip or knee replacement patients in a real-world clinical setting.

BACKGROUND: Thromboprophylaxis is recommended for patients undergoing total hip or total knee replacement (THR, TKR). An international, open-label, prospective, observational, single-arm study in a routine clinical setting was performed to assess the safety and efficacy of dabigatran etexilate 220 mg once daily in patients undergoing THR or TKR, and in subgroups of patients with potentially increased risk of bleeding or venous thromboembolism (VTE). MATERIALS AND METHODS: Patients were ≥18 years and required to be eligible to receive dabigatran 220 mg once daily (first dose 110 mg 1-4 h after THR/TKR surgery) according to the European Summary of Product Characteristics. The primary safety and efficacy outcomes were incidence of major bleeding events (MBEs), and the composite incidence of symptomatic VTE events and all-cause mortality, respectively. RESULTS: In total, 5292 patients (median age 64 years) were enrolled and received dabigatran (2734 THR and 2558 TKR). Median drug exposure was 31 days (THR 34 days; TKR 27 days). Overall incidence of MBEs was 0.72 % (95 % confidence interval [CI] 0.51, 0.98), and this rate was comparable between types of surgery and was not significantly affected by protocol-defined risk factors. The overall incidence of symptomatic VTE and all-cause mortality was 1.04 % (95 % CI 0.78, 1.35); the only significant risk factor was history of VTE events (odds ratio 5.59; 95 % CI 2.53, 11.08). A post-hoc analysis showed that the incidence of MBEs in this observational study was similar to or lower than those reported in previous phase 3 trials. CONCLUSIONS: Results from this observational study of dabigatran etexilate administered to patients undergoing THR or TKR surgery are reassuring and supportive of those obtained in dabigatran phase 3 trials. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00846807.

Safety and efficacy of switching from low molecular weight heparin to dabigatran in patients undergoing elective total hip or knee replacement surgery.

BACKGROUND: The aim of this study was to assess the safety and efficacy of switching therapy from low molecular weight heparin (LMWH; enoxaparin) to dabigatran for prevention of venous thromboembolic events (VTE) in patients undergoing elective total hip or knee replacement surgery (THR/TKR). METHODS: This was a prospective, multicenter, open-label, single-arm, observational, study in patients undergoing THR or TKR who were to receive enoxaparin 40 mg for thromboprophylaxis. Enoxaparin was initiated before or after surgery according to local practice, and was switched to dabigatran 220 mg once daily at a time point chosen by the investigator. The coprimary endpoints were major bleeding events, and the composite of symptomatic VTE and all-cause mortality, from last use of enoxaparin to 24 h after last intake of dabigatran. RESULTS: Altogether, 168 (81 THR, 87 TKR) patients were enrolled, of whom 161 received both enoxaparin and dabigatran, 2 received dabigatran only and 5 received enoxaparin only. The median time of the first dabigatran tablet was 24.0 h after the last LMWH dosage and the median number of days on dabigatran treatment was 36 days. No symptomatic VTE or death occurred during the study. One major bleeding event was seen at the surgical site and required treatment cessation. Three minor bleeding events were observed. CONCLUSIONS: In the normal clinical setting, switching from LMWH to dabigatran in patients who had undergone THR and TKR was safe and effective in preventing VTE. The reported adverse events and serious adverse events were consistent with the known safety profile for dabigatran. Switching from a subcutaneous to an oral anticoagulant may offer greater convenience in the outpatient setting after discharge. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT01153698.

Oral dabigatran etexilate versus enoxaparin for venous thromboembolism prevention after total hip arthroplasty: pooled analysis of two phase 3 randomized trials.

BACKGROUND: Two phase 3 trials compared 28-35 days of treatment with oral dabigatran 220 mg or 150 mg (RE-NOVATE) or 220 mg (RE-NOVATE II) once daily with subcutaneous enoxaparin 40 mg once daily for prevention of venous thromboembolism (VTE) after elective total hip arthroplasty. METHODS: This prespecified pooled analysis compared the outcomes for the dabigatran 220 mg dose with enoxaparin, which included 4,374 patients. Total VTE (venographic and symptomatic) plus all-cause mortality (primary efficacy), major VTE (proximal deep vein thrombosis [DVT] or non-fatal pulmonary embolism) plus VTE-related death, and bleeding events were evaluated. Efficacy analysis was based on the modified intention-to-treat (ITT) population and safety analysis was based on all treated patients. The common risk difference (RD) for dabigatran versus enoxaparin was estimated using a fixed effects model. RESULTS: Total VTE and all-cause mortality occurred in 6.8 % (114/1,672) and 7.7 % (129/1,682) (RD:-0.8 %, 95 % confidence interval [CI] -2.6 to 0.9) for dabigatran and enoxaparin, respectively. Major VTE plus VTE-related mortality occurred in 2.7 % (46/1,714) and 4.0 % (69/1,711) (RD: -1.4 %, 95 % CI -2.6 to -0.2) of patients receiving dabigatran 220 mg and enoxaparin, respectively. Major bleeding occurred in 1.7 % (37/2,156) and 1.3 % (27/2,157) (RD: 0.5 %, 95 % CI -0.2 to 1.2), for dabigatran and enoxaparin respectively. CONCLUSIONS: Extended prophylaxis with oral dabigatran 220 mg once daily was as effective as enoxaparin 40 mg once daily in reducing the risk of total VTE and all-cause mortality after total hip arthroplasty, with a similar bleeding profile. The clinically relevant outcome of major VTE and VTE-related death was significantly reduced with dabigatran versus enoxaparin. TRIAL REGISTRATION: NCT00657150 and NCT00168818.

Treatment of venous thromboembolism - effects of different therapeutic strategies on bleeding and recurrence rates and considerations for future anticoagulant management.

Effective treatment of venous thromboembolism (VTE) strikes a balance between prevention of recurrence and bleeding complications. The current standard of care is heparin followed by a vitamin K antagonist such as warfarin. However, this option is not without its limitations, as the anticoagulant effect of warfarin is associated with high inter- and intra-patient variability and patients must be regularly monitored to ensure that anticoagulation is within the narrow target therapeutic range. Several novel oral anticoagulant agents are in the advanced stages of development for VTE treatment, some of which are given after an initial period of heparin treatment, in line with current practice, while others switch from high to low doses after the initial phase of treatment. In this review we assess the critical considerations for treating VTE in light of emerging clinical data for new oral agents and discuss the merits of novel treatment regimens for patients who have experienced an episode of deep vein thrombosis or pulmonary embolism.

Type of anaesthesia and the safety and efficacy of thromboprophylaxis with enoxaparin or dabigatran etexilate in major orthopaedic surgery: pooled analysis of three randomized controlled trials.

BACKGROUND: There has been a shift towards greater use of neuraxial over general anaesthesia for patients undergoing total hip or knee arthroplasty. Furthermore, suggestions that peripheral nerve block may reduce adverse effects have recently been put forward. Although older studies showed a reduction in venous thromboembolism (VTE) with neuraxial compared with general anaesthesia, this difference has not been confirmed in studies using effective current thromboprophylaxis. We used a large data set to investigate the pattern of anaesthesia usage, and whether anaesthesia type affects efficacy and bleeding outcomes of thromboprophylaxis overall, within each treatment group, or for the novel oral anticoagulant dabigatran etexilate versus enoxaparin. METHODS: Three previously reported trials compared 220 mg and 150 mg dabigatran etexilate once daily with enoxaparin after knee or hip arthroplasty. A pooled analysis was performed in patients receiving general or neuraxial anaesthesia, or the combination of either with peripheral nerve block (n = 8062). Outcome measures were major VTE plus VTE-related mortality, major bleeding and major plus clinically relevant bleeding events. RESULTS: General, neuraxial and combination anaesthesia were used in 29%, 52% and 19% of patients, respectively. Differences in efficacy and safety between anaesthesia subgroups were small and not significant, except for a slightly higher rate of major VTE and VTE-related mortality with general versus neuraxial anaesthesia (odds ratio: 1.40; 95% confidence interval: 1.03-1.90; p = 0.035) in the overall population. There were no significant effects of anaesthesia type on efficacy or safety of dabigatran etexilate versus enoxaparin. CONCLUSIONS: Anaesthesia type did not greatly affect efficacy and safety outcomes in the pooled population of all three treatment groups. The efficacy and safety of dabigatran etexilate was comparable with enoxaparin, regardless of type of anaesthesia. TRIAL REGISTRATION: ClinicalTrials.gov identifiers: NCT00168805, NCT00168818, NCT00152971.

Switching from enoxaparin to dabigatran etexilate: pharmacokinetics, pharmacodynamics, and safety profile.

PURPOSE: Dabigatran etexilate is an oral, reversible, direct thrombin inhibitor licensed for the prevention of venous thromboembolism and stroke prevention in patients with atrial fibrillation. The aim of this study was to investigate whether, and to what extent, a switch from enoxparin to dabigatran etexilate affects the pharmacokinetic (PK) and pharmacodynamic (PD) parameters and safety profile of dabigatran. METHODS: Enoxaparin 40 mg was administered subcutaneously once daily for 3 days followed by a single dose of dabigatran etexilate 220 mg (test treatment) on day 4 in an open-label, two-way cross-over trial in healthy volunteers. Dabigatran plasma levels were measured using a validated high-performance liquid chromatography tandem mass spectrometry method. Anticoagulant activity was measured using a number of clotting tests, including prothrombinase-induced clotting time (PiCT), activated partial thromboplastin time (aPTT), ecarin clotting time (ECT), and diluted thrombin time (dTT). RESULTS: PK, PD, and safety data were available for 23 subjects for each treatment. The adjusted geometric mean test/reference ratio of area under the concentration-time curve for total dabigatran was 84% (90% confidence interval 67.2-105.0%) and 86% (67.0-110.0%) for maximum plasma concentration. The PiCT test/reference ratio, which represents the activity of enoxaparin and dabigatran, was elevated by approximately 15% for peak maximum effect ratio to baseline and total area under the effect curve (AUEC0₋48) activity, suggesting that some anticoagulant activity of enoxaparin was still present. Enoxaparin pre-treatment increased the AUEC0₋48 of activated partial thromboplastin time by approximately 14%. All other dabigatran-related PD markers were unaffected. Tolerability was good, with only mild and reversible adverse events during the treatment. CONCLUSION: Prior administration of enoxaparin did not meaningfully affect the PK or PD properties of dabigatran, and the switch from enoxaparin to dabigatran etexilate was well tolerated among the study subjects. These data support the safety of switching patients from enoxaparin to dabigatran etexilate.

Dalteparin dose-dependently increases ROTEM(®) thrombelastography parameters only at supratherapeutic anti-factor Xa levels: an in vitro study.

1. The low molecular weight heparin (LMWH) dalteparin is used, for example, to prevent primary venous thromboembolism in patients undergoing surgery or in medically ill patients. The anticoagulant activity of dalteparin can be monitored by measuring anti-factor Xa levels and activated partial thromboplastin time (aPTT); however, aPTT is an unreliable parameter in this case. The aim of the present in vitro study was to evaluate the thrombelastograph ROTEM(®) (Tem International, Munich, Germany) with respect to determining the anticoagulant activity of dalteparin at therapeutic and supratherapeutic plasma concentrations. 2. The ROTEM(®) parameters, namely coagulation time (CT), clot formation time (CFT) and maximum clot firmness (MCF), were measured using the reagents EXTEM and INTEM (Pentapharm, Munich, Germany) at increasing concentrations of dalteparin (0.01-10 µg/mL, which corresponded to anti-factor Xa levels of 1-1000 U/mL, respectively). 3. The mean CT measured using EXTEM was found to increase from 65.4 ± 27.9 s at baseline to 173.3 ± 112.2 s and 332.2 ± 200.7 s at drug concentrations of 1 and 10 µg/mL, respectively (P < 0.0001 for both). Moreover, the mean CFT value (EXTEM) increased from 97.7 ± 21.5 s at baseline to 187.6 ± 115.2 s (P = 0.0001) at a drug concentration of 10 µg/mL, which is greater than the therapeutic anti-factor Xa concentrations for LMWH. The results obtained when INTEM was used as the reagent were similar to those obtained using EXTEM. 4. In conclusion, the results indicate that the thrombelastograph ROTEM(®) can detect the anticoagulant effects of dalteparin only at supratherapeutic levels of anti-factor Xa.

Dabigatran versus Warfarin for Acute Venous Thromboembolism in Elderly or Impaired Renal Function Patients: Pooled Analysis of RE-COVER and RE-COVER II.

Management of acute venous thromboembolism (VTE) with anticoagulants in elderly patients and those with chronic kidney disease poses special challenges. The RE-COVER and RE-COVER II trials showed that dabigatran 150 mg twice daily was as effective as warfarin over 6 months in preventing recurrent VTE, with a lower bleeding risk. We now assess the effects of old age and renal impairment (RI) on pooled trial outcomes in 5,107 patients: 4,504 aged <75 years and 603 aged ≥75 years. The primary efficacy outcome was symptomatic VTE/VTE-related death. Safety outcomes were centrally adjudicated major bleeding events (MBEs), MBEs or clinically relevant non-major bleeding events (MBEs/CRBEs) and any bleeds. Baseline renal function was categorized as normal, mild RI or moderate RI. A total of 3,698 had normal renal function and 1,100 and 237 had mild and moderate RI, respectively (23 patients with severe RI and 49 with missing creatinine clearance data were not included). For dabigatran, VTE/VTE-related death decreased from 3.1% (normal renal function) to 1.9% for mild RI and to 0.0% for moderate RI. For warfarin, the event rates were 2.6, 1.6 and 4.1%, respectively. Overall, major bleeding increased with increasing RI (p = 0.0037) and with age (p = 0.4350), with no apparent difference between the dabigatran and warfarin patients. Dabigatran shows better efficacy than warfarin in RI and in the elderly patients, probably because of an increase in the concentration of dabigatran. However, bleeding risk increases with both dabigatran and warfarin in the presence of RI.

Effects of synthetic progestagens on autonomic tone, neurohormones and C-reactive protein levels in young healthy females in reproductive age.

BACKGROUND: Heart rate variability and baroreceptor sensitivity are measures of autonomic control. While progestagen-containing replacement therapy in postmenopausal women adversely affects autonomic balance, the impact of hormonal contraceptives with synthetic progestagens on autonomic activity, neurohormones and C-reactive protein levels is not well characterized. METHODS AND RESULTS: We analyzed parameters of heart rate variability and baroreceptor sensitivity in young healthy females without (n = 27) or on oral contraceptives with synthetic progestagens (n = 31). Demographic characteristics were not different among the examined groups. Total power (controls: 5682+/-3618 vs. hormones: 4800+/-2957 ms2; NS), standard deviation of beat-to-beat intervals (SDNN; 66+/-24 vs. 63+/-20 ms; p = 0.74), other time- and frequency-dependent parameters of heart rate variability and baroreceptor sensitivity (6.0+/-3.2 vs. 6.5+/-2.7 ms/mm Hg; NS) were not significantly different among the groups. Total cholesterol and triglyceride as well as C-reactive protein (CRP) levels were significantly higher in users of hormonal contraceptives than in non-users (cholesterol: 187+/-37 vs. 166+/-28 mg/dL; p = 0.05; triglycerides: 110+/-35 vs. 68+/-30 mg/dL; p = 0.01; CRP: 2.7+/-2.1 vs. 1.0+/-1.4 mg/L; p < 0.001). Heart rate variability, baroreceptor sensitivity, lipid parameters and CRP levels were not affected during the ovarian cycle in non-users of hormonal contraception. CONCLUSIONS: The use of oral contraceptives containing synthetic progestagens was not associated with a modulation of autonomic tone, while lipid parameters and CRP levels were adversely affected. These data suggest that synthetic progestagens in modern oral contraceptives do not modulate the autonomic balance, but probably affect the atherogenic risk profile of young females in reproductive age.

The discovery of dabigatran etexilate for the treatment of venous thrombosis.

INTRODUCTION: Venous thromboembolism (VTE) can be life-threatening and requires anticoagulant treatment; for many years, vitamin K antagonists, e.g. warfarin, were the only oral anticoagulants available for long-term treatment. Although highly effective, they have many limitations including a slow onset, a multitude of drug-drug and drug-food interactions, and a narrow therapeutic range. These limitations spurred the search for non-vitamin K antagonist oral anticoagulants (NOACs), such as dabigatran etexilate. AREAS COVERED: The authors illustrate the progression of preclinical and clinical studies leading to the development of dabigatran, the only approved NOAC to act by direct thrombin inhibition. They focus on molecule discovery, animal models of thrombosis, clinical trials and post-launch activities in VTE treatment. EXPERT OPINION: Dabigatran demonstrated comparable efficacy to the highly effective warfarin, and a more favourable safety profile in trials of VTE treatment. A favourable anticoagulant safety profile in addition to efficacy is essential for VTE treatment. Availability of the dabigatran-specific reversal agent, idarucizumab, provides a means of rapidly reversing the anticoagulant effect if required. Future investigations into the optimal duration of VTE treatment and an evaluation of the impact of idarucizumab, in real-world studies, could provide valuable information to help optimise treatment for selected patients.

Treatment of acute pulmonary embolism with dabigatran versus warfarin. A pooled analysis of data from RE-COVER and RE-COVER II.

Dabigatran was non-inferior to warfarin for prevention of recurrent venous thromboembolism (VTE), and dabigatran had a lower rate of bleeding compared with warfarin in two large-scale randomised trials, RE-COVER and RE-COVER II. In this study, we investigate the efficacy and safety of dabigatran versus warfarin according to the index event that qualified the patient for enrollment, either symptomatic pulmonary embolism (PE) with or without deep-vein thrombosis (DVT), or DVT alone. We then analyse the anticoagulant effect of dabigatran vs warfarin on patients enrolled with PE. The pooled dataset for the efficacy analysis consisted of 2553 and 2554 patients who were randomised to dabigatran and warfarin, respectively. Recurrent VTE/VTE-related death during the study period and additional 30-day follow-up occurred in 2.7 % of all patients on dabigatran and in 2.4 % on warfarin (hazard ratio [HR] 1.09 [95 % confidence interval 0.77, 1.54]). In patients with PE as their index event, recurrent VTE/VTE-related death occurred in 2.9 % vs 3.1 % of patients (HR 0.93 [0.53, 1.64]). There were significantly fewer major bleeding events in patients treated with dabigatran than with warfarin (HR 0.60 [0.36, 0.99]). The pattern was similar both in patients with PE and in those with DVT alone as the index event. These analyses of the pooled dataset from the RE-COVER and RE-COVER II trials indicate that dabigatran is as effective as warfarin in preventing recurrent VTE, regardless of whether patients present with symptomatic PE (with or without DVT) or with symptomatic DVT alone. Dabigatran was also associated with a lower risk of bleeding than warfarin, regardless of the index event.

An open-label study of the pharmacokinetics and pharmacodynamics of dabigatran etexilate 150mg once daily in Caucasian patients with moderate renal impairment undergoing primary unilateral elective total knee or hip replacement surgery.

BACKGROUND: In adults with moderate renal impairment (creatinine clearance [CrCl] 30-50mL/min) undergoing total hip or knee replacement (THR/TKR), the recommended dose of dabigatran etexilate is 150mg once daily (qd). We investigated the steady state pharmacokinetics, pharmacodynamics and safety in these patients. METHODS: Single-arm, open-label phase 4 study (NCT01184989) in Caucasian patients receiving dabigatran etexilate 75mg 1-4h after surgery and 150mg qd on days 2-10 (TKR) or days 2-35 (THR). Plasma total dabigatran concentrations (day 6±1) were determined by high-performance liquid chromatography tandem mass spectrometry and indirectly using the commercially available diluted thrombin time (dTT) assay (Hemoclot® Thrombin Inhibitors). RESULTS: Of 112 patients (mean CrCl 42.5mL/min, age 79.1years, 69.6% female), 100 completed the study. Geometric mean trough and peak dabigatran concentrations were 47.5ng/mL (10th-90th percentile 19.7-120) and 166ng/mL (49.1-364), respectively. There were four major bleeding events and no venous thromboembolic events. Dabigatran concentrations determined from dTT (and falling within the assay range of 50-500ng/mL) underestimated actual values by 7.6% (90% confidence interval 5.3, 9.9), which is within the acceptance limits of ±15%. CONCLUSIONS: These findings in Caucasians with moderate renal impairment undergoing THR or TKR support the use of the 150mg qd dose of dabigatran etexilate. With adequate set-up, calibration and quality control the dTT assay might be appropriate for situations, such as serious bleeding or a need for urgent surgery, where determination of dabigatran levels would be helpful.

Effectiveness and outcome of management strategies for dabigatran- or warfarin-related major bleeding events.

BACKGROUND: Strategies used for the management of dabigatran-related major bleeding events (MBEs), and their effectiveness have not been systematically evaluated. METHODS: Reports on 1034 individuals experiencing 1121 MBEs (696 on dabigatran, and 425 on warfarin) in 5 phase III randomized controlled trials were assessed independently by two investigators. RESULTS: MBEs were managed either by drug discontinuation only (37%), or drug discontinuation with either transfusion of only red cell concentrates (38%), or plasma (23%). Few MBEs (2%) were treated with coagulation factor concentrates. The effectiveness of the management was assessed as good in significantly larger proportion of MBEs on dabigatran (91%) than on warfarin (84%, odds ratio [OR] 1.68; 95% confidence interval [CI], 1.14-2.49), which was consistent with the lower 30-day mortality (OR (OR 0.66; 95% CI, 0.44-1.00)). The effectiveness of bleeding management in non-traumatic bleeding was better in patients with dabigatran than with warfarin (OR 1.82; 95% CI, 1.18-2.79) but was similar in traumatic bleeding (OR 0.75; 95% CI, 0.25-2.30). The relative effectiveness of management of bleeding and 30-day mortality rates across other key subgroups of patients or sites of bleeding, the use of platelet inhibitors, age-, sex- and renal function subgroups, were comparable in MBEs on dabigatran or warfarin. CONCLUSION: Despite the unavailability of a specific antidote at the time of these studies, bleeding in patients receiving dabigatran was managed in the overwhelming majority of patients without coagulation factor concentrates, with comparable or superior effectiveness and lower 30-day mortality rates versus those who bleed while receiving warfarin.

Observational study of dabigatran etexilate 150mg in patients with moderate renal impairment undergoing elective total hip or knee replacement.

INTRODUCTION: The standard dabigatran etexilate dosage for prevention of venous thromboembolism (VTE) after elective total hip or knee replacement (THR/TKR) is 220mg once daily (qd), with 150mg qd for patients with moderate renal impairment. As clinical trial experience in patients with moderate renal impairment was limited at the time of approval, we conducted an observational study to evaluate the 150mg qd dose. MATERIALS AND METHODS: This open-label, prospective, uncontrolled, observational study in patients with creatinine clearance (CrCl) 30-50mL/min was conducted in seven European countries. Patients received 75mg dabigatran etexilate 1-4h after surgery and 150mg qd on days 2-10 (TKR) or 2-35 (THR), per the European Summary of Product Characteristics. Coprimary outcomes were major bleeding events (MBEs) and a composite of symptomatic VTE and all-cause mortality. RESULTS: 428 renally impaired patients with median CrCl 43.4mL/min (range 30.0-49.9), and median age 80years (range 32-96) received dabigatran etexilate: median treatment duration THR 31days, TKR 28days. Ten MBEs occurred in nine patients (2.1%; 95% confidence interval [CI]: 1.0-4.0; THR 1.8%; TKR 2.4%); none were fatal or involved a critical organ. Symptomatic VTE and all-cause mortality occurred in three patients (0.7%; 95% CI: 0.1-2.0; THR 0.9%; TKR 0.5%). Overall, 54 patients discontinued treatment prematurely, including 35 due to an adverse event (nine bleeding-related) and 16 switching to another anticoagulant. CONCLUSIONS: Dabigatran etexilate 150mg qd had a good safety profile and was efficacious in fragile, elderly, renally impaired patients undergoing THR or TKR. These findings from the clinical practice setting add to the existing clinical trial data.

Bleeding events with dabigatran or warfarin in patients with venous thromboembolism.

Dabigatran was as effective as warfarin for the acute treatment of venous thromboembolism in the RE-COVER and RE-COVER II trials. We compared the incidence of bleeding with dabigatran versus warfarin in pooled data from these studies. The localisation, bleeding severity, and the impact of key factors on the incidence of bleeding, were compared between the dabigatran and warfarin treatment group. Altogether, 2553 patients received dabigatran and 2554 warfarin, each for a mean of 164 days. The incidence of any bleeding event was significantly lower with dabigatran (hazard ratio [HR] 0.70; 95% confidence interval [CI], 0.61-0.79), as was the incidence of the composite of MBEs and clinically relevant non-major bleeding events (HR 0.62; 95% CI, 0.50-0.76). The incidence of major bleeding events (MBEs) was also significantly lower with dabigatran in the double-dummy phase (HR, 0.60; 95%CI, 0.36-0.99) but not statistically different between the two treatment arms when the entire treatment period is considered (HR 0.73 95% CI, 0.48-1.11). Increasing age, reduced renal function, Asian ethnicity, and concomitant antiplatelet therapy were associated with higher bleeding rates in both treatment groups. The reduction in bleeding with dabigatran compared to warfarin was consistent among the subgroups and with a similar pattern for intracranial, and urogenital major bleeding. In conclusion, treatment of venous thromboembolism with dabigatran is associated with a lower risk of bleeding compared to warfarin. This reduction did not differ with respect to the location of bleeding or among predefined subgroups.

Treatment with dabigatran or warfarin in patients with venous thromboembolism and cancer.

The efficacy and safety of dabigatran for treatment of venous thromboembolism (VTE) were demonstrated in two trials. It is unclear if the results pertain to patients with cancer and VTE. Data from two randomised trials comparing dabigatran and warfarin for acute VTE were pooled. Primary efficacy outcome was symptomatic recurrent VTE and related death from randomisation to the end of the treatment period. Safety outcomes were major, major and clinically relevant non-major, and any bleeding during the oral-only treatment period. Patients with active cancer (=within 5 years) at baseline or diagnosed during the study were analysed. Compared with 4,772 patients without cancer, recurrent VTE occurred more frequently in 335 patients with cancer at any time (hazard ratio [HR] 3.3; 95 % confidence interval [CI], 2.1-5.3) and more often in 114 with cancer diagnosed during the study compared to 221 with cancer at baseline (HR 2.6; 95 % CI, 1.1-6.2). There was no significant difference in efficacy between dabigatran and warfarin for cancer at baseline (HR 0.75; 95 % CI, 0.20-2.8) or diagnosed during the study (HR 0.63; 95 % CI, 0.20-2.0). Major bleeding (HR 4.1; 95 % CI, 2.2-7.5) and any bleeding (HR 1.5; 95 % CI, 1.2-2.0) were more frequent in patients with cancer than without, but with similar incidence in cancer with dabigatran or warfarin. In conclusion, in cancer patients, dabigatran provided similar clinical benefit as warfarin. VTE recurrence or bleeding were similar in patients on dabigatran or warfarin. The efficacy of dabigatran has not been assessed in comparison with low-molecular-weight heparin.

Porcine spermatozoa contain more than one membrane progesterone receptor.

Progesterone has been shown to be a physiologically relevant inducer of the sperm acrosome reaction. A novel protein intrinsic to microsomal membranes, membrane progesterone receptor (mPR, now termed progesterone membrane receptor component 1, PGMRC1) that binds progesterone with high affinity has been cloned from porcine liver previously, and corresponding antibodies mitigate the progesterone induced acrosome reaction. In this study we aimed at the localization of mPR in porcine spermatozoa. Immunostaining suggested the exclusive occurrence of mPR in a hardly accessible place, possibly the inner acrosomal membrane, with digitonin dramatically increasing the number of positively stained cells. Consistent with the structure prediction for mPR, its short N-terminus (NT) but not the large C-terminal part becomes accessible from outside after digitonin treatment as evidenced by the staining pattern of antibodies directed against different regions of the protein. However, digitonin treatment solubilizes a progesterone binding activity of approximately 140 kDa molecular weight, that is different from mPR, which remains in the cell membrane as demonstrated by Western blotting. Ligand binding studies confirm the dissimilarity of mPR and the digitonin-soluble progesterone binding protein. Chemical modification studies also indicate that the digitonin-soluble progesterone binding protein has a binding site that differs from that of mPR. It is concluded that more than one progesterone receptor is present in porcine spermatozoa.