Cancer cells BXPC3 and MCF7 differentially reverse the inhibition of thrombin generation by apixaban, fondaparinux and enoxaparin

INTRODUCTION

Cancer cells may alter the efficiency of the antithrombotic agents. To explore this possibility, the present study compared the capacity of the LMWH enoxaparin and the specific inhibitors of Xa (apixaban and fondaparinux) to inhibit thrombin generation triggered by pancreas adenocarcinoma cells (BXPC3) and human breast carcinoma cells (MCF7).

MATERIALS AND METHODS

Samples of platelet poor (PPP) or platelet rich plasma (PRP) spiked with apixaban, fondaparinux or enoxaparin were added in micro wells carrying cancer cells and assessed for thrombin generation. In the control experiment thrombin generation was triggered with tissue factor reagent.

RESULTS

The three antithrombotics inhibited thrombin generation in a concentration dependent manner. The BXPC3 and MCF7 cells reversed in a different intensity the effect of the studied agents. According to the histological type of the cancer the antithrombotic efficiency of apixaban was preserved or partially reversed. Fondaparinux, was more vulnerable to the presence of cancer cells as compared to apixaban. The effect of BXCP3 or MCF7 cells on the antithrombotic potency of enoxaparin was of similar magnitude as that on apixaban.

CONCLUSIONS

The type of cancer cells is determinant for the antithrombotic efficiency of the specific factor Xa inhibitors. In contrast it does not significantly influence the potency of enoxaparin. The present study shows that the impact of the type of cancer cells on the antithrombotic activity of the specific Xa inhibitors should not be neglected. This has to be taken into consideration for the design of dose-finding studies of the direct orally active FXa inhibitors in patients with different histological types of cancer.

Updated European Heart Rhythm Association Practical Guide on the use of non-vitamin K antagonist anticoagulants in patients with non-valvular atrial fibrillation

The current manuscript is an update of the original Practical Guide, published in June 2013[Heidbuchel H, Verhamme P, Alings M, Antz M, Hacke W, Oldgren J, et al. European Heart Rhythm Association Practical Guide on the use of new oral anticoagulants in patients with non-valvular atrial fibrillation. Europace 2013;15:625-51; Heidbuchel H, Verhamme P, Alings M, Antz M, Hacke W, Oldgren J, et al. EHRA practical guide on the use of new oral anticoagulants in patients with non-valvular atrial fibrillation: executive summary. Eur Heart J 2013;34:2094-106]. Non-vitamin K antagonist oral anticoagulants (NOACs) are an alternative for vitamin K antagonists (VKAs) to prevent stroke in patients with non-valvular atrial fibrillation (AF). Both physicians and patients have to learn how to use these drugs effectively and safely in clinical practice. Many unresolved questions on how to optimally use these drugs in specific clinical situations remain. The European Heart Rhythm Association set out to coordinate a unified way of informing physicians on the use of the different NOACs. A writing group defined what needs to be considered as 'non-valvular AF' and listed 15 topics of concrete clinical scenarios for which practical answers were formulated, based on available evidence. The 15 topics are (i) practical start-up and follow-up scheme for patients on NOACs; (ii) how to measure the anticoagulant effect of NOACs; (iii) drug-drug interactions and pharmacokinetics of NOACs; (iv) switching between anticoagulant regimens; (v) ensuring adherence of NOAC intake; (vi) how to deal with dosing errors; (vii) patients with chronic kidney disease; (viii) what to do if there is a (suspected) overdose without bleeding, or a clotting test is indicating a risk of bleeding?; (xi) management of bleeding complications; (x) patients undergoing a planned surgical intervention or ablation; (xi) patients undergoing an urgent surgical intervention; (xii) patients with AF and coronary artery disease; (xiii) cardioversion in a NOAC-treated patient; (xiv) patients presenting with acute stroke while on NOACs; and (xv) NOACs vs. VKAs in AF patients with a malignancy. Additional information and downloads of the text and anticoagulation cards in >16 languages can be found on an European Heart Rhythm Association web site (www.NOACforAF.eu).

Choosing the right drug to fit the patient when selecting oral anticoagulation for stroke prevention in atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia worldwide and is a growing health problem that is associated with a significantly increased risk of stroke and thromboembolism. Oral anticoagulant (OAC) therapy reduces the risk of stroke and all-cause mortality in patients with AF. OAC therapy is commonly given as a well-controlled vitamin K antagonist (VKA; e.g. warfarin) and can reduce the risk of stroke in AF patients by almost two-thirds. However, the widespread use of VKAs has been hampered by the unpredictable pharmacokinetic and pharmacodynamic properties of the drugs and justifiable concerns about the consequent risk of haemorrhage. The non-VKA OACs (NOACs) have revolutionized thromboprophylaxis in AF by providing therapeutic options with predictable pharmacodynamic and pharmacokinetic properties that are as efficacious as warfarin in the prevention of stroke and thromboembolism but are more convenient to use. In this review, we provide a patient-centred framework to assist clinicians in recommending the right OAC therapy to fit the individual patient with AF, including methods for stratifying the risk of stroke and haemorrhage and the chances of achieving tight control of VKA anticoagulation, and we discuss the properties of the NOACs that favour their use in particular patient cohorts.

[Non-VKA oral anticoagulants: an update for the clinical biologists]

Non-VKA oral anticoagulants (NOACs), thanks to their ease of use and their similar or superior safety/efficacy profiles versus warfarin, have now widely reached the lucrative market of anticoagulation. However, while the marketing authorization holders always claim, in a quite unclear way that no monitoring is required, accumulative evidence and cases of major bleeding have been described in the literature and reported by spontaneous reporting systems at the regulator's level. These compounds are usually given at fixed doses without routine coagulation monitoring. However, new data suggests that an assessment of the response at the individual level could improve the benefit-risk ratio of, at least dabigatran. Therefore, in certain patient populations, i.e. acute or chronic renal impairment or multiple drug interactions, measurement of drug exposure may be useful to ensure an optimal treatment response. More specific circumstances such as patients experiencing a haemorrhagic or thromboembolic event during the treatment duration, patients who require urgent surgery or an invasive procedure, or patient with a suspected overdose could benefit from such a measurement. This article aims at providing guidance on how to best estimate the intensity of anticoagulation using laboratory assays in daily practice.

Non-vitamin k antagonist oral anticoagulants do not increase cerebral microbleeds

BACKGROUND

Atrial fibrillation (AF) is a cardiac arrhythmia that frequently induces ischemic strokes. Nowadays, non-vitamin K antagonist oral anticoagulants (NOACs) have come into widespread use for cardiogenic embolism prevention in place of warfarin. Recently, cerebral microbleeds (CMBs) have been noticed for their potential implication in cerebral small vessel disease. We hypothesized that NOACs do not have an unfavorable influence over cerebral small vessels and investigated whether NOACs increase CMBs in AF patients in a prospective manner.

METHODS

We performed baseline magnetic resonance imaging (MRI) examinations on the 69 enrolled AF patients and re-examined second round of MRI 1 year later. The enrolled patients continued the same anticoagulation therapy during the meantime.

RESULTS

CMBs did not develop in the 23 patients with NOACs for 1 year. Nine patients with antiplatelets also did not develop CMBs. On the other hand, 3 of 21 patients continued on warfarin and 3 of 9 with warfarin and antiplatelets had CMBs. When divided into 2 groups according to whether the CMBs developed, significant differences in the incidence of using NOACs were observed between the 2 groups (P = .02). A multivariate regression analysis showed that warfarin was independently related to the new development of CMBs (hazard ratio, 10.75; 95% confidence interval, 1.22-94.99; P = .03).

CONCLUSIONS

This is the first report to clarify that NOACs do not increase CMBs in AF patients longitudinally in 1 year. Further consideration will be continued with a much longer follow-up in large samples.

[Prospective study of the new oral anticoagulants in private practice: cautious optimism]

BACKGROUND

The new direct oral anticoagulants (DOA) such as dabigatran, rivaroxaban or apixaban are an evolution in the management of patients requiring curative anticoagulation. However, behind the simplicity of prescribing and monitoring, several questions remain about their daily use. The aim of this prospective study was to measure the feelings of general practitioners (GP), angiologists (AP) and cardiologists (CP), potential prescribers of this new anticoagulant family.

METHOD

Between December 2012 and May 2013, a questionnaire including five open questions and 11 questions using a positioning on an analogic visual scale (AVS 0 to 10) was subjected to GP, AP and CP in Alsace.

RESULTS

Responses from 224 physicians (150 GP, 35 AP and 39 CP) were collected. Thus, 83% of GP, 83% of AP and 100% of CP were prescribers of DOA. However, among these prescribing doctors, the feeling was not the same and the trend of prescription was lower in GP (2.0 [1.1-3.2] AVS units) than in AP (3.1 [2.0-5.6]) and in CP (5.0 [1.2-8.7]) (P<0.0001 in multivariate analysis). The female doctors tended to prescribe DOA in younger patients than male doctors (respectively 66.1 [52.5-76.7] vs. 75.0 [65.7-81.0] years; P=0.004). The DOA were more considered as progress by AP and CP (respectively 7.8 [5.3-9.0] and 7.9 [7.0-8.7] AVSu) than by GP (6.1 [4.8-8.2] AVSu; P=0.02 in multivariate analysis). The answer about the eventual replacement of vitamin K antagonists by the DOA was very mixed whatever the practitioner group (5.1 [3.0-7.8] AVSu; P=0.139). The ease to use and the lack of biological monitoring were the main arguments leading to the prescription but the attitude of practitioners was very balanced by the lack of experience on the bleeding risk and the lack of available antidote.

CONCLUSIONS

If the DOA are considered as an improvement for the physicians, the enthusiasm remains cautious whatever the type of practiced medicine. The results of clinical trials and the clinical experience should better appreciate the ongoing change in the field of anticoagulation.

Drug persistence with rivaroxaban therapy in atrial fibrillation patients-results from the Dresden non-interventional oral anticoagulation registry

Aims

Worldwide, rivaroxaban is increasingly used for stroke prevention in atrial fibrillation (SPAF) but little is known about the rates of or reasons for rivaroxaban discontinuations in daily care. Using data from a prospective, non-interventional oral anticoagulation (NOAC) registry, we analysed rivaroxaban treatment persistence.

Methods and results

Persistence with rivaroxaban in SPAF was assessed in an ongoing, prospective, non-interventional registry of >2600 NOAC patients from daily care using the Kaplan–Meier time-to-first-event analysis. Reasons for and management of rivaroxaban discontinuation were assessed. Potential baseline risk factors for treatment discontinuation were evaluated using Cox regression analysis. Between October 2011 and April 2014, 1204 rivaroxaban SPAF patients were enrolled [39.3% switched from vitamin K antagonists (VKAs) and 60.7% newly treated patients]. Of these, 223 patients (18.5%) stopped rivaroxaban during follow-up (median 544 days), which translates into a discontinuation rate of 13.6 (95% CI 11.8–15.4) per 100 patient-years. Most common reasons for treatment discontinuations were bleeding complications (30% of all discontinuations), followed by other side-effects (24.2%) and diagnosis of stable sinus rhythm (9.9%). A history of chronic heart failure (HR 1.43; 95% CI 1.09–1.87; P = 0.009) or diabetes (HR 1.39; 95% CI 1.06–1.82; P = 0.018) were the only statistically significant baseline risk factors for rivaroxaban discontinuation. After discontinuation of rivaroxaban, patients received antiplatelet therapy (31.8%), VKA (24.2%), another NOAC (18.4%), heparin (9.9%), or nothing (15.7%).

Conclusion

Our data indicate that overall persistence with rivaroxaban therapy is high, with a discontinuation rate of ∼15% in the first year of treatment and few additional discontinuations thereafter.

Stroke Prevention in Atrial Fibrillation - Outcomes and Future Directions

Stroke prevention is central to the management of patients with atrial fibrillation (AF). Vitamin K antagonists (VKAs) are the established and long-standing option for stroke prevention therapy in patients with AF. However, non-VKA oral anticoagulants (NOACs) have recently been developed and demonstrated non-inferior efficacy vs VKA treatment, with fewer limitations in clinical practice and with reduced risks of major bleeding. In order to discuss the usage, efficacy and safety of NOACs, a satellite symposium was held at the Cardiostim/ EHRA Europace Congress in Nice in June 2014. At present, three NOACs, a direct thrombin inhibitor (dabigatran) and two direct factor Xa inhibitors (rivaroxaban and apixaban) have been approved in Europe for stroke prevention in patients with AF. In addition, the once-daily factor Xa inhibitor edoxaban has recently been evaluated in this setting in the phase III Effective Anticoagulation with Factor Xa Next Generation in Atrial Fibrillation - Thrombolysis In Myocardial Infarction Study 48 (ENGAGE AF-TIMI 48) that compared edoxaban 30 mg once daily (low-dose regimen) with dose-adjusted warfarin (international normalised ratio 2.0-3.0). ENGAGE AF-TIMI 48 was the largest trial with a NOAC to date, and demonstrated that both dosing regimens of once-daily edoxaban were non-inferior to well-managed warfarin treatment for the prevention of stroke or systemic embolism and also provided significant reductions in the risk of haemorrhagic stroke, cardiovascular mortality, major bleeding and intracranial bleeding. In summary, the recent availability of NOACs has enabled physicians to avoid the limitations of VKA therapy in clinical practice and tailor anticoagulant treatment to the individual patient. However, worldwide usage of oral anticoagulant therapy remains suboptimal compared with guideline recommendations, and further dissemination of its benefits may prove helpful.

The Potential Role of Edoxaban in Stroke Prevention Guidelines

With the emergence of edoxaban, the oral factor Xa inhibitors now appear consolidated as the dominant class of novel oral anticoagulants (NOACs) for stroke prevention in non-valvular atrial fibrillation (AF). The oral factor Xa inhibitors do not require an adequate time in therapeutic range to be effective, presenting a potential advantage over the vitamin K antagonists (VKAs). Guidelines are changing to reflect the increased choice of anticoagulants and as clinicians move away from the VKAs towards the relative safety and efficacy of NOACs, they must consider which one offers the best therapy for their patient. The ENGAGE-AF study was the latest phase III trial to report on the safety and efficacy of a new factor Xa inhibitor relative to warfarin. Both edoxaban 60mg once daily, and edoxaban 30mg once daily were found to be non-inferior compared to warfarin for the prevention of ischaemic stroke and systemic embolism, being associated with significantly lower rates of major bleeding, intracranial haemorrhage and cardiovascular death. A two-tiered dosing option may present clinicians with a further element of choice for the individual patient.

The Year in Cardiology 2013: valvular heart disease (focus on catheter-based interventions)

2013 was the year of transcatheter heart valve interventions. Not least because of the 2012 European guidelines on the management of valvular heart disease (VHD), the multidisciplinary heart team approach became an established concept. Decision-making, when a patient is too 'sick' for surgery and too 'healthy' for catheter-based interventions, is complex, since VHD is often seen at an older age and, as a consequence, there is a higher frequency of co-morbidity and frailty. However, before TAVI and other transcatheter heart valve interventions can be expanded to intermediate-risk patients, evidence in favour of this less invasive treatment has to be provided by upcoming randomized clinical trials.

Cancer-associated thrombosis, low-molecular-weight heparin, and the patient experience: a qualitative study

BACKGROUND

Venous thromboembolism is a common complication of cancer and its treatments. Treatment of cancer-associated thrombosis (CAT) differs from treatment of thrombosis in noncancer patients, requiring a daily injection of low-molecular-weight heparin (LMWH) for 6 months instead of an oral anticoagulant. Previous research suggested LMWH is an acceptable intervention in the treatment of CAT, yet clinical practice and therapeutic opportunities have changed in the decade since the study was conducted. Furthermore, in the previous study there was acknowledged selection bias in participant recruitment. There is increasing clinical use of the novel oral anticoagulants, although their efficacy and safety is yet to be demonstrated within the cancer population. The experience of patients receiving anticoagulation for CAT will inform future practice with respect to quality of life and adherence to anticoagulation therapy.

AIM

To explore the acceptability of long-term LMWH for the treatment of CAT in the contexts of living with cancer and quality of life.

DESIGN

Qualitative study of cancer patients who had been receiving LMWH for at least 3 months for CAT was undertaken. Audiotaped semistructured interviews were conducted and transcribed. Thematic analysis was undertaken until theoretical saturation.

SETTING/PARTICIPANTS

Fourteen patients attending a palliative care or CAT clinic were interviewed. Participants had been receiving LMWH for a median 6 months.

RESULTS

Participants reported distressing symptoms associated with symptomatic CAT, which they rated as worse than their cancer experiences. LMWH was considered an acceptable intervention despite challenges of long-term injections. Several adaptive techniques were reported to optimize ongoing injections. Participants would only favor a novel oral anticoagulant if it was equivalent to LMWH in efficacy and safety.

CONCLUSION

Although LMWH remains an acceptable intervention for the treatment of CAT, its long-term use is associated with bruising and deterioration of injection sites. These are considered an acceptable trade-off against their strongly negative experiences of symptomatic venous thromboembolism.

Left atrial appendage occlusion: opportunities and challenges

Stroke prevention in patients with atrial fibrillation is a growing clinical dilemma as the incidence of the arrhythmia increases and risk profiles worsen. Strategies in patients with nonvalvular atrial fibrillation have included anticoagulation with a variety of drugs. Knowledge that stroke in this setting typically results from thrombus in the left atrial appendage has led to the development of mechanical approaches, both catheter-based and surgical, to occlude that structure. Such a device, if it were safe and effective, might avoid the need for anticoagulation and prevent stroke in the large number of patients who are currently not treated with anticoagulants. Regulatory approval has been difficult due to trial design challenges, balance of the risk-benefit ratio, specific patient populations studied, selection of treatment in the control group, and specific endpoints and statistical analyses selected. Accumulating data from randomized trials and registries with longer-term follow-up continues to support a role for left atrial appendage exclusion from the central circulation as an alternative to anticoagulation in carefully-selected patient populations.

Management of major bleeding complications and emergency surgery in patients on long-term treatment with direct oral anticoagulants, thrombin or factor-Xa inhibitors: proposals of the working group on perioperative haemostasis (GIHP) - March 2013

Direct new oral anticoagulants (NOACs) - inhibitors of thrombin or factor Xa - are intended to be used largely in the treatment of venous thromboembolic disease or the prevention of systematic embolism in atrial fibrillation, instead of vitamin K antagonists. Like any anticoagulant treatment, they are associated with spontaneous or provoked haemorrhagic risk. Furthermore, a significant proportion of treated patients are likely to be exposed to emergency surgery or invasive procedures. Given the absence of a specific antidote, the action to be taken in these situations must be defined. The lack of data means that it is only possible to issue proposals rather than recommendations, which will evolve according to accumulated experience. The proposals presented here apply to dabigatran (Pradaxa(®)) and rivaroxaban (Xarelto(®)); data for apixaban and edoxaban are still scarce. For urgent surgery with haemorrhagic risk, the drug plasma concentration should be less or equal to 30ng/mL for dabigatran and rivaroxaban should enable surgery associated with a high bleeding risk. Beyond that, if possible, the intervention should be postponed by monitoring the drug concentration. The course to follow is then defined according to the NOAC and its concentration. If the anticoagulant dosage is not immediately available, worse propositions, based on the usual tests (prothrombin time and activated partial thromboplastin time), are presented. However, these tests do not really assess drug concentration or the risk of bleeding that depends on it. In case of serious bleeding in a critical organ, the effect of anticoagulant therapy should be reduced using a non-specific procoagulant drug as a first-line approach: activated prothrombin complex concentrate (aPCC) (FEIBA(®) 30-50U/kg) or non-activated PCC (50U/kg). In addition, for any other type of severe haemorrhage, the administration of a procoagulant drug, which is potentially thrombogenic in these patients, is discussed according to the NOAC concentration and the possibilities of mechanical haemostasis.