Dabigatran versus warfarin in patients with mechanical heart valves

Perioperative management of oral anticoagulants: a focus on target-specific oral anticoagulants

Although warfarin has historically been the dominant oral anticoagulant, newer target-specific oral anticoagulants (TSOACs) have been introduced in the marketplace in the past few years. Dabigatran, rivaroxaban, and apixaban, collectively referred to as TSOACs, have undergone extensive testing in comparison with warfarin and other anticoagulants for a variety of conditions. Compared with warfarin, the shorter time to peak effect, shorter half-life, and fewer drug-drug interactions have helped make the TSOACs attractive alternatives to warfarin for the prevention and treatment of thromboembolic disease associated with orthopedic surgery and atrial fibrillation as well as for the treatment of venous thromboembolism. However, their unique properties pose a challenge for their management in the perioperative period. This article reviews the current guideline-based approach to perioperative management of anticoagulants, the clinical data, and the recommendations supporting use of the TSOACs in the perioperative period. The article also addresses common pitfalls in their perioperative management. By understanding a few key properties of the new oral anticoagulants and with careful perioperative planning, physicians can ensure that their patients will safely undergo most surgical procedures with minimal disruption of their chronic anticoagulation.

Addressing barriers to optimal oral anticoagulation use and persistence among patients with atrial fibrillation: Proceedings, Washington, DC, December 3-4, 2012

Approximately half of patients with atrial fibrillation and with risk factors for stroke are not treated with oral anticoagulation (OAC), whether it be with vitamin K antagonists (VKAs) or novel OACs (NOACs); and of those treated, many discontinue treatment. Leaders from academia, government, industry, and professional societies convened in Washington, DC, on December 3-4, 2012, to identify barriers to optimal OAC use and adherence and to generate potential solutions. Participants identified a broad range of barriers, including knowledge gaps about stroke risk and the relative risks and benefits of anticoagulant therapies; lack of awareness regarding the potential use of NOAC agents for VKA-unsuitable patients; lack of recognition of expanded eligibility for OAC; lack of availability of reversal agents and the difficulty of anticoagulant effect monitoring for the NOACs; concerns with the bleeding risk of anticoagulant therapy, especially with the NOACs and particularly in the setting of dual antiplatelet therapy; suboptimal time in therapeutic range for VKA; and costs and insurance coverage. Proposed solutions were to define reasons for oral anticoagulant underuse classified in ways that can guide intervention and improve use, to increase awareness of stroke risk as well as the benefits and risks of OAC use via educational initiatives and feedback mechanisms, to better define the role of VKA in the current therapeutic era including eligibility and ineligibility for different anticoagulant therapies, to identify NOAC reversal agents and monitoring strategies and make knowledge regarding their use publicly available, to minimize the duration of dual antiplatelet therapy and concomitant OAC where possible, to improve time in therapeutic range for VKA, to leverage observational data sets to refine understanding of OAC use and outcomes in general practice, and to better align health system incentives.

Eligibility and preference of new oral anticoagulants in patients with atrial fibrillation: comparison between patients with versus without stroke

BACKGROUND AND PURPOSE

Recent randomized clinical trials (RCTs) have evaluated the benefit of new oral anticoagulants in reducing the risk of vascular events and bleeding complications in patients with atrial fibrillation (AF). However, abundant and strict enrollment criteria may limit the validity and applicability of results of RCTs to clinical practice. We estimated the eligibility for participation in RCTs of an unselected group of patients with AF. In addition, we compared features favoring new oral anticoagulant use between patients with versus without stroke. Randomized Evaluation of Long-Term Anticoagulation Therapy

METHODS

We applied enrollment criteria of 4 RCTs (RE-LY, ROCKET-AF, ARISTOTLE, and ENGAGE-AF-TIMI 48) to 695 patients with AF taking warfarin, prospectively and consecutively collected at a university medical center; 500 patients with and 195 patients without stroke. Time in therapeutic range and bleeding risk scheme (anticoagulation and risk factors in atrial fibrillation) were also measured.

RESULTS

The proportions of patients fulfilling the trial enrollment criteria varied, ranging from 39% to 72.8%, depending on the differences in indications/contraindications among studies and presence/absence of stroke. The main reasons for ineligibility for RCTs were hemorrhagic risk (anticoagulation and risk factors in atrial fibrillation [ATRIA] score) (10.8%-40.5%) and planned cardioversion (5.1%-7.7%) for nonstroke patients, and a low creatinine clearance (5.6%-9.2%) and higher risk of bleeding (15.2%-20.8%) for patients with stroke. When compared with nonstroke patients, patients with stroke showed a lower time in therapeutic range (54.4±42.8% versus 65.4±34.9%, especially with severe disability) and a high hemorrhagic risk (ATRIA score) (3.06±2.30 versus 2.18±2.16) (P<0.05 in both cases).

CONCLUSIONS

Patients enrolled in RCTs are partly representative of patients with AF in clinical practice. When time in therapeutic range and bleeding tendency with warfarin use were considered, the use of new oral anticoagulants was preferred in patients with stroke than in nonstroke patients, but they were more likely to be excluded in RCTs.

Dental Procedures in Patients with Atrial Fibrillation and New Oral Anticoagulants

This review discusses the basic pharmacology of new oral anticoagulants that are used for prevention of thromboembolism in patients with atrial fibrillation. It presents available evidence, and provides recommendations for the management of patients requiring invasive procedures in dental practice.

Advances in clinical cardiology

Multiple, potentially practice-changing cardiology trials have been presented or published over the past year. In this paper, we summarize and place in clinical context, new data regarding management of acute coronary syndrome and ST-elevation myocardial infarction (copeptin assessment, otamixaban, cangrelor, prasugrel, sodium nitrite, inclacumab, ranolazine, preventive coronary intervention of non-culprit lesions, immediate thrombolytic therapy versus transfer for primary intervention), new coronary intervention data (thrombectomy, radial access, pressure wire fractional flow reserve, antiplatelet therapy duration and gene-guidance, permanent and biodegradable polymers, coronary bifurcation and strategies), and coronary artery bypass data (off pump vs. on pump). Latest trials in trans-aortic valve implantation, heart failure (eplerenone, aliskiren, spironolactone, sildenafil, dopamine, nesiritide, omecamtiv mecarbil, the algisyl left ventricular augmentation device, and echo-guided cardiac resynchronization), atrial fibrillation (edoxaban, dabigatran, and ablation), cardiac arrest (hypothermia, LUCAS™ mechanical chest compression), and cardiovascular prevention (vitamins, renal denervation for resistant hypertension, renal artery stenting, saxagliptin, alogliptin, and gastric banding) are also discussed.

Target-specific oral anticoagulants: practice issues for the clinician

Venous thromboembolism and atrial fibrillation are among the most common cardiovascular disorders in the United States. For over 50 years, the standard of care has been anticoagulation with vitamin K antagonists. However, the numerous limitations of vitamin K antagonists led to the development of target-specific oral anticoagulants. Dabigatran, rivaroxaban, apixaban, and edoxaban have been shown to be as effective as warfarin in the treatment and prevention of venous thromboembolism and prevention of stroke in nonvalvular atrial fibrillation. This article compares the basic pharmacologic properties of these anticoagulants, reviews the data supporting their use, and discusses practical clinical issues including measurement of the anticoagulation effect, reversal strategies, and management of patients prior to surgery.

Non-vitamin K antagonist oral anticoagulants (NOACs): clinical evidence and therapeutic considerations

Warfarin, a vitamin K antagonist, is the most widely used oral anticoagulant in the world. It is cheap and effective, but its use is limited in many patients by unpredictable levels of anticoagulation, which increases the risk of thromboembolic or haemorrhagic complications. It also requires regular blood monitoring and dose adjustment. New classes of drugs, non-vitamin K antagonist oral anticoagulants (NOACs), are now supported as alternatives to warfarin. Three NOACs are licensed: dabigatran, a direct thrombin inhibitor, and rivaroxaban and apixaban, antagonists of factor Xa. NOACs do not require routine blood monitoring or dose adjustment. They have a rapid onset and offset of action and fewer food and drug interactions. Current indications include treatment and prophylaxis of venous thromboembolism and prevention of cardioembolic disease in non-valvular atrial fibrillation. Effective antidotes are lacking and some caution must be used in severe renal impairment, but favourable trial evidence has led to their widespread adoption. Research is ongoing, and an increase in their use and indications is expected in the coming years.

Periprocedural management of patients on anticoagulants

Every year, new studies are undertaken to address the complex issue of periprocedural management of patients on anticoagulants and antiplatelet medications. In addition, newer drugs add to the confusion among clinicians about how to best manage patients taking these agents. Using the most recent data, guidelines, and personal experience, this article discusses recommendations and presents simplified algorithms to assist clinicians in the periprocedural management of patients on anticoagulants.

Anticoagulation strategies for the management of postoperative atrial fibrillation

Patients undergoing thoracic and cardiac procedures are at the highest risk for postoperative atrial fibrillation (POAF). POAF is associated with poor short-term and long-term outcomes, including high rates of early and late stroke, and late mortality. Patients with POAF that persists for longer than 48 hours should be anticoagulated on warfarin. Three new oral anticoagulants are available for the treatment of nonvalvular atrial fibrillation and have been found to be as efficacious or superior to warfarin in the prevention of stroke in high-risk patients, with similar to lower rates of major bleeding, and lower rates of intracranial hemorrhage.

Direct oral anticoagulants: integration into clinical practice

The introduction of direct oral anticoagulants (OACs) for the treatment and prevention of thromboembolic disease represents a shift from the traditional vitamin K antagonist-based therapies, which have been the mainstay of treatment for almost 60 years. A challenge for hospital formularies will be to manage the use of direct OACs from hospital to outpatient settings. Three direct OACs—apixaban, dabigatran and rivaroxaban—are widely approved across different indications, with rivaroxaban approved across the widest breadth of indications. A fourth direct OAC, edoxaban, has also completed phase III trials. Implementation of these agents by physicians will require an understanding of the efficacy and safety profile of these drugs, as well as an awareness of renal function, comedication use, patient adherence and compliance. Optimal implementation of direct OACs in the hospital setting will provide improved patient outcomes when compared with traditional anticoagulants and will simplify the treatment and prevention of thromboembolic diseases.

On the monitoring of dabigatran treatment in "real life" patients with atrial fibrillation

INTRODUCTION

The oral direct thrombin inhibitor dabigatran is increasingly used to prevent thromboembolic stroke in patients with atrial fibrillation (AF). Routine laboratory monitoring is currently not recommended, but measurements of dabigatran and/or its effect are desirable in certain situations. We studied dabigatran exposure and compared different tests for monitoring of dabigatran in a real-life cohort of AF patients.

MATERIAL AND METHODS

Ninety AF patients (68 ± 9 years, 67% men, mean CHADS2 score 1.5) were treated with dabigatran 150 (n=73) or 110 mg BID (n=17). Trough plasma concentrations of total and free dabigatran by liquid chromatography-tandem mass-spectrometry (LC-MS/MS) were compared to indirect measurements by Hemoclot thrombin inhibitors (HTI) and Ecarin clotting assay (ECA), as well as PT-INR and aPTT.

RESULTS

Total plasma dabigatran varied 20-fold (12-237 ng/mL with 150 mg BID) and correlated well with free dabigatran (r(2)=0.93). There were strong correlations between LC-MS/MS and HTI or ECA (p<0.001) but these assays were less accurate with dabigatran below 50 ng/mL. The aPTT assay was not dependable and PT-INR not useful at all. There were weak correlations between creatinine clearance (Cockcroft-Gault) and LC-MS/MS, HTI and ECA (p<0.001 for all). A high body weight with normal kidney function was associated with low dabigatran levels.

CONCLUSIONS

HTI and ECA reflect the intensity of dabigatran anticoagulation, but LC-MS/MS is required to quantify low levels or infer absence of dabigatran. Most real life patients with a normal creatinine clearance had low dabigatran levels suggesting a low risk of bleeding but possibly limited protection against stroke.

[Novel oral anticoagulants in patients with atrial fibrillation, how to avoid accidents?]

Know the indications of these new drugs, and respect them. Do not confuse easiness of administration and absence of precautions. Renal function: a key parameter before and during treatment. Know when to use a low-dose drug regimen. Cardioversion: lack of safety evidence for some drugs. Drug interactions: beware of P-glycoprotein and cytochrome P450.

Thromboembolism, major bleeding and mortality in patients with mechanical heart valves- a population-based cohort study

INTRODUCTION

Low incidences of thromboembolism (TE) and bleeding in patients with mechanical heart valves (MHV) have previously been reported. This study assesses the incidence of and clinical risk factors predicting TE, major bleeding and mortality in a clinical setting.

METHODS AND RESULTS

All 546 patients undergoing anticoagulation treatment due to MHV replacement at hospitals in Malmö and Sundsvall in Sweden were monitored during 2008-2011 and the incidence of TE, major bleeding and mortality was prospectively followed. There were 398, 122 and 26 patients in the aortic group (AVR), mitral (MVR) group and the combined aortic/mitral valve group respectively. The incidence of TE was 1.8 and 2.2 per 100 patient-years in the AVR group MVR group respectively. The corresponding incidences of bleeding were 4.4 and 4.6, respectively. Independent predictor of thromboembolism was vascular disease (Odds ratio {OR}: 4.2; 95% CI: 1.0-17.4). Predictor of bleeding was previous bleeding (OR: 2.7; 95% CI: 1.4-5.3). Independent predictors of mortality was age (Hazard ratio {HR}: 1.03; 95% CI: 1.00-1.05), hypertension (HR: 2.4; 95% CI: 1.3-4.5), diabetes (HR: 2.4; 95% CI: 1.3-4.3) and alcohol overconsumption (HR: 5.2; 95% CI: 1.7-15.9). Standardized mortality/morbidity ratio for mortality and AMI was 0.99 (95% CI: 0.8-1.2) and 0.87 (95% CI: 0.5-1.2) respectively.

CONCLUSION

The incidence of TE and major bleeding in this unselected clinical population exceeds that of previously reported retrospective and randomized trials. Despite this, mortality is equal to that of the general population.

Dabigatran etexilate and risk of myocardial infarction, other cardiovascular events, major bleeding, and all-cause mortality: a systematic review and meta-analysis of randomized controlled trials

Background

Signals of an increased risk of myocardial infarction (MI) have been identified with dabigatran etexilate in randomized controlled trials (RCTs).

Methods and Resules

We conducted searches of the published literature and a clinical trials registry maintained by the drug manufacturer. Criteria for inclusion in our meta‐analysis included all RCTs and the availability of outcome data for MI, other cardiovascular events, major bleeding, and all‐cause mortality. Among the 501 unique references identified, 14 RCTs fulfilled the inclusion criteria. Stratification analyses by comparators and doses of dabigatran etexilate were conducted. Peto odds ratio (OR_PETO) values using the fixed‐effect model (FEM) for MI, other cardiovascular events, major bleeding, and all‐cause mortality were 1.34 (95% CI 1.08 to 1.65, P=0.007), 0.93 (95%CI 0.83 to 1.06, P=0.270), 0.88 (95% CI 0.79 to 0.99, P=0.029), and 0.89 (95% CI 0.80 to 1.00, P=0.041). When compared with warfarin, OR_PETO values using FEM were 1.41 (95% CI 1.11 to 1.80, P=0.005), 0.94 (95%CI 0.83 to 1.06, P=0.293), 0.85 (95% CI 0.76 to 0.96, P=0.007), and 0.90 (95% CI 0.81 to 1.01, P=0.061), respectively. In RCTs using the 150‐mg BID dosage, the OR_PETO values using FEM were 1.45 (95% CI 1.11 to 1.91, P=0.007), 0.95 (95% CI 0.82 to 1.09, P=0.423), 0.92 (95% CI 0.81 to 1.05, P=0.228), and 0.88 (95% CI 0.78 to 1.00, P=0.045), respectively. The results of the 110‐mg BID dosage were mainly driven by the RE‐LY trial.

Conclusions

This meta‐analysis provides evidence that dabigatran etexilate is associated with a significantly increased risk of MI. This increased risk should be considered taking into account the overall benefit in terms of major bleeding and all‐cause mortality.

Beyond warfarin: a patient-centered approach to selecting novel oral anticoagulants for stroke prevention in atrial fibrillation

BACKGROUND

Warfarin reduces stroke in patients with atrial fibrillation. However, its narrow therapeutic index and need for chronic monitoring are barriers to its optimal utilization in many patients. The recent introduction of 3 novel oral anticoagulants (NOACs), as alternatives to warfarin, may change the eligibility and management of patients with nonvalvular atrial fibrillation (NVAF) who require systemic anticoagulation.

PURPOSE

To summarize contemporary indications for anticoagulation in NVAF, and to help provide patient-centered clinical decision making for selecting warfarin or 1 of the NOACs (dabigatran, rivaroxaban, apixaban) based on randomized trials and mechanistic data for each drug.

DATA SOURCES AND STUDY SELECTION

The primary clinical outcome trials of warfarin and the NOACs, pharmacologic studies, and briefing documents from the US Food and Drug Administration were reviewed.

DATA EXTRACTION AND DATA SYNTHESIS

In randomized trials, NOACs were consistently noninferior to warfarin for reducing stroke or systemic embolism in patients with NVAF, with reductions in intracranial bleeding as well. However, NOACs have several important drug-drug interactions, exclusion criteria for specific patient subgroups (eg, severe renal disease), and each medication may have a different impact on other clinical outcomes such as myocardial infarction or gastrointestinal bleeding. Benefits of the new drugs are particularly pronounced when international normalized ratio levels on warfarin are labile.

CONCLUSIONS

Warfarin continues to play an important role in the prevention of stroke or systemic embolism in NVAF. Among selected patients, the use of NOACs provides equal or superior benefit, without the need for chronic anticoagulation monitoring or ongoing dose titration.

'Real-world' antithrombotic treatment in atrial fibrillation: The EORP-AF pilot survey

BACKGROUND

Current guidelines strongly recommend that oral anticoagulation should be offered to patients with atrial fibrillation and ≥1 stroke risk factors. The guidelines also recommend that oral anticoagulation still should be used in the presence of stroke risk factors irrespective of rate or rhythm control.

METHODS

In an analysis from the dataset of the EURObservational Research Programme on Atrial Fibrillation Pilot Survey (n = 3119), we examined antithrombotic therapy prescribing, with particular focus on the risk factors determining oral anticoagulation or antiplatelet therapy use.

RESULTS

When oral anticoagulation was used among admitted patients in whom no pharmacologic cardioversion, electrical cardioversion, or catheter ablation was performed or planned, vitamin K antagonist therapy was prescribed in the majority (72.2%), whereas novel oral anticoagulants were used in the minority (7.7%). There was no significant difference in bleeding risk factors among the patients treated with the different types of antithrombotic therapies, except for those with chronic kidney disease, in whom oral anticoagulation was less commonly used (P = .0318). Antiplatelet therapy was more commonly used in patients with a high Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile international normalized ratio, Elderly (>65 years), Drugs/alcohol concomitantly score (≥2) (P < .0001). More oral anticoagulation use was associated with female gender (P = .0245). Less novel oral anticoagulant use was associated with valvular heart disease (P < .0001), chronic heart failure (P = .0010), coronary artery disease (P < .0001), and peripheral artery disease (P = .0092). Coronary artery disease was the strongest reason for combination therapy with oral anticoagulation plus antiplatelet drug (odds ratio, 8.54; P < .0001). When the Congestive heart failure, Hypertension, Age ≥75 [Doubled], Diabetes, Stroke [Doubled]-Vascular disease, Age 65-74, and Sex category [female] score was used, 95.6% of patients with a score ≥1 received antithrombotic therapy, with 80.5% of patients with a score ≥1 receiving oral anticoagulation. Of note, 83.7% of those with a score ≥2 received antithrombotic therapy. Of the latter, 70.9% of those with a score ≥2 received oral anticoagulation, vitamin K antagonists were used in 64.1%, and novel oral anticoagulants were used in 6.9%.

CONCLUSIONS

The EURObservational Research Programme on Atrial Fibrillation Pilot Survey provides contemporary data on oral anticoagulation prescribing by European cardiologists for atrial fibrillation. Although the uptake of oral anticoagulation (mostly vitamin K antagonist therapy) has improved since the Euro Heart Survey a decade ago, antiplatelet therapy is still commonly prescribed, with or without oral anticoagulation, whereas elderly patients are commonly undertreated with oral anticoagulation.

Personalized medicine: importance of clinical interpretative skills for real-world patient care

Sequencing of the human genome led to great hopes and expectations for a 'genomics revolution' where disease diagnosis as well as therapies would be based on an individual's genetic makeup. Although significant progress has been made, a number of challenging hurdles must be overcome prior to the broader adoption and implementation of pharmacogenomics and personalized medicine as a part of standard patient care. One aspect of pharmacogenomics-based personalized medicine that has not garnered as much attention, a key focus of this perspective, is the importance of interpreting pharmacogenomic test results in a patient-specific clinical context, and expert physicians and other allied health care providers with the requisite expertise in clinical pharmacology and genomics who are able to provide such services.

Controversies regarding the new oral anticoagulants for stroke prevention in patients with atrial fibrillation

Increasing use of the new oral anticoagulants (NOACs) – dabigatran, rivaroxaban, and apixaban – has prompted considerable discussion in the medical community even as warfarin remains the mainstay of therapy. This article raises 10 controversial issues regarding the use of NOACs for stroke prevention in patients with atrial fibrillation, and offers a review of the latest available evidence. We provide a brief overview of the mechanism and dosing of these drugs, as well as a summary of the key clinical trials that have brought them into the spotlight. Comparative considerations relative to warfarin such as NOAC safety, efficacy, bleeding risk, reversibility, drug-transitioning and use in patients well controlled on warfarin are addressed. Use in select populations such as the elderly, those with coronary disease, renal impairment, or on multiple anti-platelet drugs is also discussed. Finally, we consider such specific issues as comparative efficacy, off-label use, cost, rebound and management during events. Ultimately, the rise of the NOACs to mainstream use will depend on further data and clinical experience amongst the medical community.

Misconceptions, diagnostic challenges and treatment opportunities in bioprosthetic valve thrombosis: lessons from a case series

OBJECTIVES

Bioprosthetic valve thrombosis (BPVT) is a rare but potentially life-threatening complication. Current guidelines favour surgery or thrombolysis as initial treatment. We set forth to characterize timing, diagnostic criteria and treatment strategies in BPVT.

METHODS

A free-text search tool was used to identify patients diagnosed with BPVT at Mayo Clinic between 1997 and 2013. We compared patients treated initially with vitamin K antagonists (VKA group; N = 15) versus surgery/thrombolysis (non-VKA group; N = 17).

RESULTS

Peak incidence of BPVT was 13-24 months after implantation in both groups. VKA and surgery/thrombolysis decreased prosthetic mean gradients to a similar extent (VKA group: 13 ± 5 to 6 ± 2 mmHg in mitral position, 9 ± 3 to 5 ± 1 mmHg in tricuspid position and 39 ± 3 to 24 ± 7 mmHg in aortic/pulmonary position; non-VKA group: 16 ± 12 to 5 ± 1 mmHg in mitral, 10 ± 5 to 4 ± 1 mmHg in tricuspid and 57 ± 9 to 18 ± 6 mmHg in aortic position; P = 0.59 for group effect). NYHA class improved in 11 of 15 patients in the VKA group and 10 of 17 patients in the non-VKA group (P = 0.39). There were no deaths, strokes or recognized embolic events; 1 patient in each group experienced gastrointestinal bleeding requiring transfusion. Index transthoracic echocardiogram formally identified BPVT in a minority of patients.

CONCLUSIONS

BPVT may occur late after surgical implantation. VKA therapy resulted in haemodynamic and clinical improvement with minimal risk, and should be considered the first-line therapy in haemodynamically stable patients. Echocardiographic criteria for improving BPVT diagnosis are proposed.

Potential use of NOACs in developing countries: pros and cons

PURPOSE

Although vitamin K antagonists (VKAs) are effective for long-term thromboprophylaxis in atrial fibrillation (AF), their limitations have led to widespread underutilisation, especially in the developing world. Novel oral anticoagulants (NOACs) have emerged as promising alternatives to VKAs, although there are some particular considerations and challenges to their introduction in developing countries. This review summarises the current state of antithrombotic management of AF in the developing world, explores the early evidence for the NOACs and describes some of the special considerations that must be taken into account when considering the role of the NOACs within developing countries' health care systems.

METHODS

A literature search was conducted via PubMed and Google Scholar to find articles published in English between the years 2000 to 2014. Search terms used were "atrial fibrillation", "oral anticoagulants", "warfarin", "NOACs", "dabigatran", "rivaroxaban", "apixaban", "edoxaban", "time in therapeutic range", "International Normalized Ratio" "cost-effectiveness", "stroke", "adverse-drug reactions" and "drug-drug interactions", together with the individual names of developing countries as listed by the World Bank. We reviewed the results of randomized clinical trials, relevant retrospective and prospective studies, case-studies and review articles.

RESULTS

Many developing countries lack or have sporadic data on the quality of AF management, making it difficult to anticipate the potential impact of NOACs in these settings. The utilisation of anticoagulants for AF appears highly variable in developing countries. Given the issues associated with VKA therapy in many developing countries, NOACs offer some potential advantages; however, there is insufficient evidence to advocate the widespread replacement of warfarin at present. VKAs may continue to have a role in selected patients or countries, especially if alternative monitoring strategies can be utilised.

CONCLUSION

The evaluation of the introduction of NOACs should consider safety, budget concerns and the quality of oral anticoagulation care achieved by each country. Prospective registries will be important in developing countries to better elucidate the comparative safety, efficacy and cost-effectiveness of NOACs and VKAs as NOACs are introduced into practice.

Stroke prevention in atrial fibrillation: Commentary regarding the AAN's evidence-based guideline update

Atrial fibrillation is a common, potentially preventable cause of disabling stroke in the elderly, particularly in elderly women, resulting from embolism of stasis-precipitated thrombi formed in the left atrial appendage. In 1989, the first randomized clinical trial of anticoagulant therapy in atrial fibrillation showed that warfarin produced a large reduction in ischemic stroke.¹ In the ensuing 25 years, more than 40 additional randomized trials have permitted stroke prophylaxis to be importantly refined. It has been a period of remarkable progress in stroke prevention. Here, we discuss selected aspects of the American Academy of Neurology (AAN)'s evidence-based guideline update.^2.

Dabigatran anticoagulation and Stanford type A aortic dissection: lethal coincidence: Case report with literature review

BACKGROUND

Novel oral anticoagulants are now encountered in patients needing emergency surgery. Knowledge and treatment options are limited.

METHODS AND RESULT

We present the case of a 76-year-old patient who suffered from an acute Stanford type A aortic dissection, needing emergency surgical aortic repair. He was anticoagulated with dabigatran due to past atrial fibrillation. Despite haemodiafiltration, surgical revision and massive transfusion of packed red blood cells, fresh frozen plasma, platelets, coagulation factors, and recombinant factor VIIa, the patient died from intractable bleeding with sustained therapeutic levels of dabigatran.

CONCLUSION

After reviewing the literature, we summarize the limited treatment options and show possible approaches for patients treated with dabigatran needing emergency surgery.