Increased risk of intracranial hemorrhage when aspirin is combined with warfarin: A meta-analysis and hypothesis

Hemorrhage induced by antithrombotic agents: new insights from a real-world pharmacovigilance study

BACKGROUND

Hemorrhage represents the most common and serious side effect of antithrombotic agents. Many studies have compared the risk of bleeding between different antithrombotic agents, but analysis of time-to-onset for hemorrhage induced by these drugs is yet sparse.

METHODS

We conducted a retrospective study based on the adverse drug reaction reports on antithrombotic agents collected by the Henan Adverse Drug Reaction Monitoring Center. We assessed the reporting odds ratio to determine the disproportionate reporting signals for bleeding and the Weibull shape parameter was used to evaluate the time-to-onset data.

RESULTS

In the signal detection, crude low molecular weight heparin-hemorrhage was found as a positive signal. The hemorrhage for most antithrombotic agents was random failure profiles. In particular, the hazard of hemorrhage decreased over time for warfarin and clopidogrel and increased for alteplase, nadroparin, and dipyridamole.

CONCLUSION

We found that the risk of bleeding in patients taking Crude low molecular weight heparins was significantly higher compared to other antithrombotic agents, but with a small magnificence, which may be attributed to the severely irrational use of this medication under improper management. Statistics in days, results showed that the risk of bleeding decreased over time for warfarin and clopidogrel and increased for alteplase, nadroparin, and dipyridamole.

Clinical and neuroimaging risk factors associated with the development of intracerebral hemorrhage while taking direct oral anticoagulants

BACKGROUND AND AIMS

Intracerebral hemorrhage (ICH) associated with direct oral anticoagulant (DOAC) usage confers significant mortality/disability. We aimed to understand the clinical and neuroimaging features associated with developing ICH among DOAC users.

METHODS

Clinical and radiological data were collected from consecutive DOAC users with ICH (DOAC-ICH) and age-matched controls without ICH from a single referral center. The frequency/distribution of MRI markers of hemorrhage risk were assessed. Baseline demographics and neuroimaging markers were compared in univariate tests. Significant associations (p < 0.1) were entered into a multivariable regression model to determine predictors of ICH.

RESULTS

86 DOAC-ICH and 94 ICH-free patients were included. Diabetes, coronary artery disease, prior ischemic stroke, smoking history, and antiplatelet usage were more common in ICH patients than ICH-free DOAC users. In the neuroimaging analyses, severe white matter hyperintensities (WMHs), lacunes, cortical superficial siderosis (cSS), and cerebral microbleeds (CMBs) were more common in the ICH cohort than the ICH-free cohort. In the multivariable regression, diabetes [OR 3.53 95% CI (1.05-11.87)], prior ischemic stroke [OR 14.80 95% CI (3.33-65.77)], smoking history [OR 3.08 95% CI (1.05-9.01)], CMBs [OR 4.07 95% CI (1.45-11.39)], and cSS [OR 39.73 95% CI (3.43-460.24)] were independently associated with ICH.

CONCLUSIONS

Risk factors including diabetes, prior stroke, and smoking history as well as MRI biomarkers including CMBs and cSS are associated with ICH in DOAC users. Although screening MRIs are not typically performed prior to initiating DOAC therapy, these data suggest that patients of high-hemorrhagic risk may be identified.

Neurological complications of cardiovascular drugs

Cardiovascular drugs are used to treat arterial hypertension, hyperlipidemia, arrhythmias, heart failure, and coronary artery disease. They also include antiplatelet and anticoagulant drugs that are essential for prevention of cardiogenic embolism. Most neurologic complications of the cardiovascular drugs are minor or transient and are far outweighed by the anticipated benefits of treatment. Other neurologic complications are more serious and require early recognition and management. Overtreatment of arterial hypertension may cause lightheadedness or fatigue but often responds readily to dose adjustment or an alternative drug. Other drug complications may be more troublesome as in myalgia associated with statins or headache associated with vasodilators. The recognized bleeding risk of the antithrombotics requires careful calculation of risk/benefit ratios for individual patients. Many neurologic complications of cardiovascular drugs are well documented in clinical trials with known frequency and severity, but others are rare and recognized only in isolated case reports or small case series. This chapter draws on both sources to report the adverse effects on muscle, nerve, and brain associated with commonly used cardiovascular drugs.

Antithrombotics in intracerebral hemorrhage in the era of novel agents and antidotes: A review

BACKGROUND

Intracerebral hemorrhage (ICH)1 is characterized by the pathological accumulation of blood within the brain parenchyma, most commonly associated with hypertension, arteriovenous malformations, or trauma. However, it can also present in patients receiving antithrombotic drugs, either anticoagulants such as acenocoumarol/warfarin-novel oral anticoagulants or antiplatelets, for the prevention and treatment of thromboembolic disease.

OBJECTIVE

The purpose of this review is to present current bibliographic data regarding ICH irrespective of the cause, as well as post-hemorrhage use of antithrombotic agents. Moreover, this review attempts to provide guidelines concerning the termination, inversion, and of course resumption of antithrombotic therapy.

METHODS AND MATERIALS

We reviewed the most recently presented available data for patients who dealt with intracerebral hemorrhagic events while on antithrombotic agents (due to atrial fibrillation, prosthetic mechanical valves or recent/recurrent deep vein thrombosis). Furthermore, we examined and compared the thromboembolic risk, the bleeding risk, as well as the re-bleeding risk in two groups: patients receiving antithrombotic therapy versus patients not on antithrombotic therapy.

CONCLUSION

Antithrombotic therapy is of great importance when indicated, though it does not come without crucial side-effects, such as ICH. Optimal timing of withdrawal, reversal, and resumption of antithrombotic treatment should be determined by a multidisciplinary team consisting of a stroke specialist, a cardiologist, and a neurosurgeon, who will individually approach the needs and risks of each patient.

Proposal for the Rapid Reversal of Coagulopathy in Patients with Nonoperative Head Injuries on Anticoagulants and/or Antiplatelet Agents: A Case Study and Literature Review

BACKGROUND

Emergency room physicians, trauma teams, and neurosurgeons are seeing increasing numbers of head-injured patients on anticoagulants, many of whom are nonoperative. Head injury and anticoagulation can lead to devastating consequences. These patients need immediate evaluation and often reversal of anticoagulation in order to decrease their high rates of morbidity and mortality.

OBJECTIVE

To review data on the prevalence, risks, treatment, and complications of head-injured anticoagulated patients and provide a proposal for their anticoagulant management, and imaging requirements.

METHODS

A PubMed database search was performed for articles on the prevalence, risks, treatment, and complications of patients who have sustained a head injury while on anticoagulant or antiplatelet agents.

RESULTS

A total of 1877 articles were found, of which 64 were selected for use based on direct relevance, information quality, and contribution of the article to the current understanding of anticoagulated head injury patients.

CONCLUSION

There are very few guidelines for the management of nonoperative head-injured patients. Rapid reversal guided by international normalized ratio values, Platelet Function Assays, computed tomography imaging of the head, and physical exam is suggested. The proposal presented in this paper enables patient management to begin quickly in a systematic approach, with the goal of achieving a significant decrease in the morbidity and mortality for the anticoagulated head-injured patient. Rapid reversal can potentially decrease mortality by as much as 38%.

Bleeding with anticoagulant treatments

Anticoagulation with vitamin K antagonists (VKAs) is effective in the prevention and treatment of thrombotic complications in many clinical conditions, including atrial fibrillation (that represents today the most frequent indication for anticoagulant treatment), venous thromboembolism, acute coronary syndromes and after invasive cardiac procedures. Bleeding is the most important complication of VKAs and a major concern for both physicians and patients, limiting a more widespread prescription of the treatment. As a result, a non negligible proportion of all the subjects who would have a clear clinical indication for anticoagulation do not receive an effective treatment.

This review analyses the treatment- and person-associated risk factors for bleeding during VKAs. New oral anticoagulant drugs seems to overcome at least some of the limitations of VKAs. Potentially, they can allow a less demanding and more stable anticoagulant treatment, with less side-effects allowing that more patients can receive an appropriate anticoagulant treatment. Based on the so far available phase III clinical studies, it is possible to assume that these new drugs are associated with a risk of bleeding, that is probably related to the intensity of treatment.

Anticoagulants

Anticoagulants are effective in the prevention and treatment of a variety of arterial and venous thrombotic disorders but are associated with an increased risk of serious bleeding complications. Based on well documented studies of patients using vitamin K antagonists the incidence of major bleeding is 0.5%/year and the incidence of intracranial bleeding is 0.2%/year, however, in real life practice this incidence may be even higher. Risk factors for bleeding are the intensity of anticoagulation, the management strategy to keep the anticoagulant effect in the desired range, and patient characteristics. Recently, a new generation of anticoagulants have been developed and is currently evaluated in clinical trials. Initial results show a similar or superior efficacy over conventional anticoagulant agents with a good safety profile. In case of serious bleeding complications in a patient who uses vitamin K antagonists, this anticoagulant treatment can be quickly reversed by administration of vitamin K or coagulation factor concentrates. For the newer anticoagulants, quick reversal strategies are more cumbersome, although some interventions, including prothrombin complex concentrates, show promising results in initial experimental studies.

Bleeding risk assessment and management in atrial fibrillation patients

In this executive summary of a Consensus Document from the European Heart Rhythm Association, endorsed by the European Society of Cardiology Working Group on Thrombosis, we comprehensively review the published evidence and propose a consensus on bleeding risk assessments in atrial fibrillation (AF) patients. The main aim of the document was to summarise ‘best practice’ in dealing with bleeding risk in AF patients when approaching antithrombotic therapy, by addressing the epidemiology and size of the problem, and review established bleeding risk factors. We also summarise definitions of bleeding in the published literature. Patient values and preferences balancing the risk of bleeding against thromboembolism as well as the prognostic implications of bleeding are reviewed. We also provide an overview of published bleeding risk stratification and bleeding risk schema. Brief discussion of special situations (e.g. periablation, peri-devices such as implantable cardioverter defibrillators [ICD] or pacemakers, presentation with acute coronary syndromes and/or requiring percutanous coronary interventions/stents and bridging therapy) is made, as well as a discussion of the prevention of bleeds and managing bleeding complications. Finally, this document puts forwards consensus statements that may help to define evidence gaps and assist in everyday clinical practice.

Gaps in translation from trials to practice: Non-vitamin K antagonist oral anticoagulants (NOACs) for stroke prevention in atrial fibrillation

Worldwide there is a tremendous need for affordable anticoagulants that do not require monitoring. The advent of the non-warfarin oral anticoagulant drugs represents a major advance for stroke prevention in atrial fibrillation (AF). The objectives of this review are to 1) identify gaps in our current knowledge regarding use of these single target anticoagulant drugs; 2) outline the potential implications of these gaps for clinical practice, and thereby, 3) highlight areas of research to further optimise their use for stroke prevention in AF.

Venous thromboembolism in the elderly

Old age is an independent risk factor of venous thromboembolism. Nevertheless initial symptoms are often attributed to existing cardiac or pulmonary comorbidity. Once deep thromboembolism (DTE) is in focus, the synopsis of clinical findings and anamnestic clues help to take further steps to establish or rule out the diagnosis (e.g. Wells score). Treatment consists in oral anticoagulation, either by vitamin-k-antagonists or by direct oral anticoagulants (“DOACs”). Strict compliance of patients or main caregivers is essential in both cases. Simultaneous medication of platelet-inhibitingor nonsteroidal anti-inflammatory drugs – often unknown self medication – results in a raised bleeding risk and should be avoided. If longterm anticoagulation is mandatory, a strategy of sequential dose-reduced anticoagulation can be considered, especially in the case of increased bleeding-risk. Systemic fibrinolysis of pulmonary embolism goes along with a very high bleeding risk in old age and should be performed only in case of vital circulatory depression or failure.

Resuming anticoagulant therapy after intracerebral bleeding

The clinical benefit of resuming anticoagulant treatment after an anticoagulants-associated intracranial hemorrhage (ICH) is debated. No randomized trial has been conducted on this particular clinical issue. The risk of ICH recurrence from resuming anticoagulant therapy is expected to be higher after index lobar than deep ICH and in patients with not amendable risk factors for ICH. Retrospective studies have recently shown improved survival with resumption of treatment after index anticoagulants-associated ICH. Based on these evidences and on the risk for thromboembolic events without anticoagulant treatment, resumption of anticoagulation should be considered in all patients with mechanical heart valve prosthesis and in those with amendable risk factors for anticoagulants-associated ICH. Resumption with direct oral anticoagulants appears a reasonable option for non-valvular atrial fibrillation (NVAF) patients at moderate to high thromboembolic risk after deep ICH and for selected NVAF patients at high thromboembolic risk after lobar ICH. For VTE patients at high risk for recurrence, resumption of anticoagulation or insertion of vena cava filter should be tailored on the estimated risk for ICH recurrence.

Animal models of spontaneous intracerebral hemorrhage

OBJECTIVES

Intracerebral hemorrhage (ICH) is a type of stroke that results in significant mortality and morbidity. Currently there is no definitive treatment for this disease. The paucity of animal models that reflect the heterogeneity of this spontaneous human disease could be the reason.

METHODS

In this review, we searched the literature for animal models of spontaneous ICH and found eight relevant papers.

RESULTS

Two were related to hypertension and six were related to cerebral amyloid angiopathy (CAA). One model used double transgenic mice overexpressing human renin and angiotensinogen which caused the mice to be hypertensive. Induction of ICH, however required addition of a high salt diet and nitric oxide synthase inhibition. Another mouse model of hypertension employed subcutaneous angiotensin II infusion and nitric oxide synthase inhibition plus acute injections of angiotensin to further elevate blood pressure. Five CAA models were in transgenic mice overexpressing amyloid precursor protein. One relied on the natural development of CAA in squirrel monkeys.

CONCLUSIONS

While all of the spontaneous ICH models have some advantages, the disadvantages include the sporadic time of onset of ICH and variability in size and location of ICH. Since there are no known efficacious treatments for ICH, it is not known if findings in the animal models will find treatments that are effective in humans.

Antiplatelet and anticoagulant therapy after intracerebral hemorrhage

Management of patients with an indication for long-term oral antithrombotic therapy who have an intracerebral hemorrhage (ICH) presents a therapeutic dilemma. Should antithrombotic therapy be resumed, and if so, when, using what agent, and for whom? There is no consensus for answers to these questions. In the absence of randomized trials, management of antithrombotic therapy after ICH is based on a combination of observational data, pathophysiologic concepts, and decision analysis. At the heart of the decision is an assessment of the individual patient's risk of thromboembolism off antithrombotic therapy versus risk of ICH recurrence on antithrombotic therapy.

Subsequent arterial ischemic events in patients receiving anticoagulant therapy for venous thromboembolism

OBJECTIVE

Patients with acute venous thromboembolism (VTE) are at increased risk for the development of subsequent arterial ischemic events unrelated to the diagnosis of VTE. Accurate identification of VTE patients at increased risk for ischemic events during the course of anticoagulation may help to select those who would potentially benefit from concomitant therapy with anticoagulants and antiplatelets.

METHODS

We used the Registro Informatizado de Enfermedad TromboEmbólica (RIETE) Registry to assess the rate and severity of subsequent ischemic events (ie, stroke, myocardial infarction, lower limb amputation, or mesenteric ischemia) appearing during the course of anticoagulant therapy and tried to identify risk factors for these events.

RESULTS

From February 2009 to March 2014, 23,370 patients were recruited: 12,397 initially presenting with pulmonary embolism (PE) and 10,973 with deep venous thrombosis. During the course of anticoagulation (mean, 9.2 months), 597 patients developed recurrent VTE, 652 bled, 162 had ischemic events (stroke, 86; myocardial infarction, 53; limb amputation, 13; mesenteric ischemia, 11), and 2063 died. Of these, 29 patients died of recurrent PE, 83 of bleeding, and 53 of the ischemic events. On multivariable analysis, cancer (hazard ratio [HR], 1.77; 95% confidence interval [CI], 1.21-2.61), chronic lung disease (HR, 1.54; 95% CI, 1.05-2.26), renal insufficiency (HR, 1.72; 95% CI, 1.25-2.36), anemia (HR, 1.54; 95% CI, 1.11-2.14), prior artery disease (HR, 1.84; 95% CI, 1.29-2.64), and diabetes (HR, 1.58; 95% CI, 1.10-2.27) independently predicted the risk for ischemic events. Most of these variables also predicted major bleeding (cancer, chronic lung disease, renal insufficiency, anemia, and prior artery disease) or recurrent PE (cancer, chronic lung disease, anemia, and prior artery disease).

CONCLUSIONS

In patients receiving anticoagulation for VTE, the mortality due to PE recurrences was lower than the mortality due to ischemic events. Most independent predictors for ischemic events were also predictors for major bleeding and for recurrent PE.

Is bleeding a necessary evil? The inherent risk of antithrombotic pharmacotherapy used for stroke prevention in atrial fibrillation

Current European atrial fibrillation (AF) guidelines have assigned a strong recommendation for the initiation of antithrombotic therapy to prevent thromboembolism in all but those AF patients at low risk (or with contraindications). Furthermore, the selection of antithrombotic therapy is based on the absolute risks of thromboembolism and bleeding, and the relative risk and benefit for a given patient. By their very mechanism of action, antithrombotic agents used for stroke prevention in AF will potentially increase the risk of bleeding events. Moreover, the introduction of novel oral anticoagulation agents have introduced new, hitherto ill-defined, deficiencies in the authors' knowledge with respect to anticoagulation monitoring, availability of direct antidotes, drug-drug interactions and the ability to appropriately control and reverse their actions if bleeding events occur. The authors present a comprehensive review on all aspects of bleeding related to currently licensed antithrombotic agents used for stroke prevention in patients with AF.

New orally active anticoagulants in critical care and anesthesia practice: the good, the bad and the ugly

With the adoption of dabigatran, rivaroxaban, and apixaban into clinical practice, a new era has arrived in the practice of oral anticoagulants. Venous thromboembolism (VTE) has traditionally been underdiagnosed and under treated in Asia. With increasing longevity, the diagnosis and the need for management of atrial fibrillation (AF) and VTE is likely to increase significantly. The new orally active anticoagulants (NOACs) have reasonably filled the lacunae that clinicians traditionally faced when treating patients with vitamin K antagonist (VKA). Unlike VKA, NOACs do not need frequent monitoring. Therefore, more patients are likely to get therapeutic effects of anticoagulation and thus reduce morbidity and mortality associated with VTE and AF. However, the clinicians need to be circumspect and exercise caution in use of these medications. In particular (in geriatric population), the clinicians should look out for drug-drug interactions and underlying renal insufficiency. This would ensure therapeutic efficacy and minimize bleeding complications. Here, it is important to note that the antidote for NOACs is not available and is a major concern if emergency surgical procedure is required in their presence.

Intracerebral hemorrhage: new challenges and steps forward

Intracerebral hemorrhage (ICH) is a significant cause of morbidity and mortality. With the aging population, increased use of anticoagulants, and changing racial and ethnic landscape of the United States, the incidence of ICH will increase over the next decade. Improvements in preventative strategies to treat hypertension and atrial fibrillation are necessary to change the trajectory of this increase. Advances in the understanding of ICH at the vascular and molecular level may pave the way to new treatment options. This article discusses the epidemiology, pathophysiology, and current treatment options for patients with ICH. Differences in outcome and treatment between patients taking and not taking anticoagulant therapies are considered.

Intracerebral hemorrhage in patients receiving oral anticoagulation therapy

Intracerebral hemorrhage (ICH) in patients with oral anticoagulation therapy is an increasingly prevalent problem in large part due to the aging population and the increased use of anticoagulants for patients at high risk of thrombosis. Warfarin has been virtually the only outpatient anticoagulant choice until fairly recently. The development of subcutaneously injected heparinoids, and more recently, of direct thrombin inhibitors, has made the treatment and prognostication of ICH in anticoagulated patients more difficult. In this review, we will review the current state of diagnosis, prognostication, and treatment for patients with this often-devastating type of bleeding. We will focus on warfarin therapy, because the preponderance of evidence comes from studies of warfarin treatment. Where there is evidence, we will contrast warfarin with some of the newer treatment modalities. We review the evidence of the 4 major reversal agents for warfarin, vitamin K, prothrombin complex concentrates, activated factor VII, and fresh frozen plasma as well as rational treatment choices. We offer possible treatments for the newer anticoagulants based on the limited evidence available. Finally, we review recommendations from the major societies and studies that support early and aggressive therapies in intensive care units with dedicated neurological specialists.

Adverse drug events associated with vitamin K antagonists: factors of therapeutic imbalance

Background

Adverse drug events (ADE) occur frequently during treatment with vitamin K antagonists (AVK) and contribute to increase hemorrhagic risks.

Methods

A retrospective study was conducted over a period of 2 years. Patients treated with AVK and admitted to the emergency room of a tertiary care hospital in Beirut were included. The aim of the study was to identify ADE characterized by a high international normalized ratio (INR) and to determine the predictive factors responsible for these events. Statistical analysis was performed with the SPSS statistical package.

Results

We included 148 patients. Sixty-seven patients (47.3%) with an INR above the therapeutic range were identified as cases. The control group consisted of 81 patients (54.7%) with an INR within the therapeutic range. Hemorrhagic complications were observed in 53.7% of cases versus 6.2% of controls (P < 0.0001). No significant difference was noticed between cases and controls regarding the indication and the dose of AVK. Patients aged over 75 years were more likely to present an INR above the therapeutic range (58.2%, P = 0.049). Recent infection was present in 40.3% of cases versus 6.2% of controls (P < 0.0001) and hypoalbuminemia in 37.3% of cases versus 6.1% of controls (P < 0.0001). Treatment with antibiotics, amiodarone, and anti-inflammatory drugs were also factors of imbalance (P < 0.0001).

Conclusion

Many factors may be associated with ADE related to AVK. Monitoring of INR and its stabilization in the therapeutic range are important for preventing these events.

Stroke Prevention in Atrial Fibrillation

New orally administered anticoagulants will simplify stroke-prevention strategies in patients with atrial fibrillation (AF). Novel anticoagulants, such as dabigatran etexilate, a direct thrombin inhibitor, and rivaroxaban, a direct factor Xa inhibitor, have been approved by the US Food and Drug Administration for the prevention of stroke and systemic embolism in patients with nonvalvular AF. In addition, the factor Xa inhibitor apixaban has been reported to be as effective as warfarin in a large, randomized clinical trial, and the efficacy of edoxaban is being assessed in a phase III warfarin comparison trial. This review discusses the limitations of vitamin K antagonist therapy for patients with AF and establishes the need for alternative, effective anticoagulation with an improved benefit–risk ratio for the prevention of stroke. Novel anticoagulants have the potential to provide convenient, effective stroke prophylaxis without many of the issues inherent in the use of traditional agents.

Systematic review of methods used in meta-analyses where a primary outcome is an adverse or unintended event

BACKGROUND

Adverse consequences of medical interventions are a source of concern, but clinical trials may lack power to detect elevated rates of such events, while observational studies have inherent limitations. Meta-analysis allows the combination of individual studies, which can increase power and provide stronger evidence relating to adverse events. However, meta-analysis of adverse events has associated methodological challenges. The aim of this study was to systematically identify and review the methodology used in meta-analyses where a primary outcome is an adverse or unintended event, following a therapeutic intervention.

METHODS

Using a collection of reviews identified previously, 166 references including a meta-analysis were selected for review. At least one of the primary outcomes in each review was an adverse or unintended event. The nature of the intervention, source of funding, number of individual meta-analyses performed, number of primary studies included in the review, and use of meta-analytic methods were all recorded. Specific areas of interest relating to the methods used included the choice of outcome metric, methods of dealing with sparse events, heterogeneity, publication bias and use of individual patient data.

RESULTS

The 166 included reviews were published between 1994 and 2006. Interventions included drugs and surgery among other interventions. Many of the references being reviewed included multiple meta-analyses with 44.6% (74/166) including more than ten. Randomised trials only were included in 42.2% of meta-analyses (70/166), observational studies only in 33.7% (56/166) and a mix of observational studies and trials in 15.7% (26/166). Sparse data, in the form of zero events in one or both arms where the outcome was a count of events, was found in 64 reviews of two-arm studies, of which 41 (64.1%) had zero events in both arms.

CONCLUSIONS

Meta-analyses of adverse events data are common and useful in terms of increasing the power to detect an association with an intervention, especially when the events are infrequent. However, with regard to existing meta-analyses, a wide variety of different methods have been employed, often with no evident rationale for using a particular approach. More specifically, the approach to dealing with zero events varies, and guidelines on this issue would be desirable.

Intracranial hemorrhage in atrial fibrillation patients during anticoagulation with warfarin or dabigatran: the RE-LY trial

BACKGROUND AND PURPOSE

Intracranial hemorrhage is the most devastating complication of anticoagulation. Outcomes associated with different sites of intracranial bleeding occurring with warfarin versus dabigatran have not been defined.

METHODS

Analysis of 18 113 participants with atrial fibrillation in the Randomized Evaluation of Long-term anticoagulant therapY (RE-LY) trial assigned to adjusted-dose warfarin (target international normalized ratio, 2-3) or dabigatran (150 mg or 110 mg, both twice daily).

RESULTS

During a mean of 2.0 years of follow-up, 154 intracranial hemorrhages occurred in 153 participants: 46% intracerebral (49% mortality), 45% subdural (24% mortality), and 8% subarachnoid (31% mortality). The rates of intracranial hemorrhage were 0.76%, 0.31%, and 0.23% per year among those assigned to warfarin, dabigatran 150 mg, and dabigatran 110 mg, respectively (P<0.001 for either dabigatran dose versus warfarin). Fewer fatal intracranial hemorrhages occurred among those assigned dabigatran 150 mg and 110 mg (n=13 and n=11, respectively) versus warfarin (n=32; P<0.01 for both). Fewer traumatic intracranial hemorrhages occurred among those assigned to dabigatran (11 patients with each dose) compared with warfarin (24 patients; P<0.05 for both dabigatran doses versus warfarin). Independent predictors of intracranial hemorrhage were assignment to warfarin (relative risk, 2.9; P<0.001), aspirin use (relative risk, 1.6; P=0.01), age (relative risk, 1.1 per year; P<0.001), and previous stroke/transient ischemic attack (relative risk, 1.8; P=0.001).

CONCLUSIONS

The clinical spectrum of intracranial hemorrhage was similar for patients given warfarin and dabigatran. Absolute rates at all sites and both fatal and traumatic intracranial hemorrhages were lower with dabigatran than with warfarin. Concomitant aspirin use was the most important modifiable independent risk factor for intracranial hemorrhage.

Current anticoagulant safety

INTRODUCTION

Currently used anticoagulants such as unfractionated heparin, low-molecular-weight heparin and vitamin K antagonists, have several drawbacks, mostly related to safety. In this review, we will briefly discuss and compare the safety of anticoagulation therapy with 'old' and new agents.

AREAS COVERED

Safety issues with anticoagulation therapy are mostly related to bleeding. The intensity of anticoagulation is related to the risk of bleeding and thus, for the efficacy not to be affected, must be maintained at the lower effective intensity. Several improvements have been made in the management of anticoagulation therapy; these include monitoring, pathology-based treatment schemes taking into account patient characteristics, patient education and the introduction of anticoagulation centers. Safety of novel anticoagulants is encouraging.

EXPERT OPINION

Novel agents have the potential to compete with existing therapy for thromboprophylaxis, treatment and stroke prevention in atrial fibrillation. Promising results have emerged from trials comparing them with existing treatment. Not long from now we will see these new agents in the armamentarium of antithrombotic drugs.

Determinants of intracranial hemorrhage incidence in patients on oral anticoagulation followed at the Lahey clinic

Oral anticoagulation with warfarin is widely used to treat venous and arterial thromboembolic disease (Ansell et al. Chest 133(6 suppl):160S-198S, 2008). Its administration is associated with a risk of intracranial hemorrhage (ICH), a devastating complication which usually results in death or severe disability (Fang et al. Am J Med,120(8):700-705, 2007; Rosand et al. Arch Intern Med, 164(8):880-884, 2004). The international normalized ratio (INR) is one of the factors which can help determine the risk of ICH in a given individual (Singer et al. Circ Cardiovasc Qual Outcomes, 2(4):297-304, 2009). Using the DoseResponse(®) patient database at our institution, we carried a retrospective nested matched case-control study to identify patient characteristics associated with the occurrence of ICH. The database was queried for the years 2004-2009. Each case was matched by month to four control patients having a routine INR determination for the monitoring of chronic anticoagulation. The following characteristics were captured: bleeding type, INR, age, sex, blood pressure, hemoglobin, creatinine, presence or history of pertinent comorbid conditions, intake of antiplatelet agents (aspirin or thienopyridine) and indication for anticoagulation. The relationship between those risk factors and the odds ratio of ICH was determined with conditional logistic regression. Fifty cases of ICH were retrieved. When correcting for pertinent variables, the odds ratio of ICH increased significantly for higher INR values, with a quadratic relationship noted in the model. Increasing mean blood pressure seemed to be associated with a higher risk of ICH, also in an exponential manner. Rising hemoglobin values on the other hand seemed to have a protective effect against such events. About 50% of cases of ICH occurred in or below the therapeutic INR range. The intake of antiplatelet agent was found to be associated with ICH in univariate analysis only. The INR is an important predictor for the incidence of ICH, but in this study an elevated measurement was found in only half of cases. Mean blood pressure appears to be another important determinant of the risk of ICH in the anticoagulated patient population.

Spontaneous intraventricular hemorrhage associated with prolonged diosmin therapy

BACKGROUND

The prevalent use of anticoagulation in a growing elderly population has led to an increasing incidence of intracerebral hemorrhage. Furthermore, the understanding of the interactions and adverse effects of oral anticoagulants when used with non-FDA approved drugs is limited. Diosmin is one such non-FDA approved drug which is a semisynthetic, phlebotropic supplement with multiple microcirculatory effects. We report a case of a patient on oral anticoagulation and diosmin, who presented with spontaneous intraventricular hemorrhage, and discuss the possible etiology behind this rare event.

METHODS

A retrospective chart review and a comprehensive search of the literature using the PubMed database were performed.

RESULTS

A 77-year old female with a 6 week history of warfarin therapy and a several year history of diosmin use presented with severe bitemporal headache. Computed tomography scan revealed an acute hemorrhage within the right ventricle without associated intraparenchymal hemorrhage. International normalized ratio measured 1.8 and was corrected using fresh frozen plasma and vitamin K. She was discharged without neurological deficits.

CONCLUSIONS

Diosmin inhibits platelet aggregation and prolongs the effect of norepinephrine on venous tone, leading to increased venoconstriction. The combined effect of chronic microcirculatory hypertension and inhibition of platelet aggregation due to diosmin may have predisposed to spontaneous hemorrhage in this anticoagulated patient. Individual cases such as this serve as a reminder that over-the-counter dietary supplements may be associated with serious adverse events. The practicing clinician should be aware of this possible adverse event when evaluating patients on oral anticoagulation and chronic diosmin treatment.

Bleeding risk and reversal strategies for old and new anticoagulants and antiplatelet agents

The most important adverse effect of antithrombotic treatment is the occurrence of bleeding. In the case of severe bleeding in a patient who uses anticoagulant agents or when a patient on anticoagulants needs to undergo an urgent invasive procedure, it may be useful to reverse anticoagulant treatment. Conventional anticoagulants such as vitamin K antagonists may be neutralized by administration of vitamin K or prothrombin complex concentrates, whereas heparin and heparin derivatives can be counteracted by protamine sulphate. The anti-hemostatic effect of aspirin and other antiplatelet strategies can be corrected by the administration of platelet concentrate and/or desmopressin, if needed. Recently, a new generation of anticoagulants with a greater specificity towards activated coagulation factors as well as new antiplatelet agents have been introduced and these drugs show promising results in clinical studies. A limitation of these new agents may be the lack of an appropriate strategy to reverse the effect if a bleeding event occurs, although experimental studies show hopeful results for some of these agents.

[Pharmacologically-induced neurocatastrophes]

Drug-induced adverse reactions represent a significant health problem in developed countries. These events cause 5% of hospital admissions and are one of the main causes of mortality. Neurological manifestations are among the most frequent. This article reviews catastrophic cerebrovascular situations and confusional syndromes, as well as epilepsy, structural encephalopathy, neuromuscular disorders, catastrophic movement disorders and infections, all of which can be drug-induced.

Anticoagulation remains underused in prevention of stroke associated with atrial fibrillation: insights from two consecutive national surveys

BACKGROUND

Atrial fibrillation (AF) is a major risk factor of ischemic stroke. We tested whether the adoption of the CHADS(2) score in clinical guidelines has impacted treatment strategies for stroke prevention, and examined how AF affects stroke outcome.

METHODS

In the setting of two national surveys [National Acute Stroke Israeli Surveys; all patients hospitalized for stroke in Israel during February-March 2004, and March-April 2007] data of patients with and without AF were analyzed with respect to patient characteristics, use of anticoagulation, stroke severity, clinical course, and long-term outcome.

RESULTS

Of 3040 patients with acute ischemic stroke, 586 patients (19%) had a history of AF. Severe strokes on admission were significantly more frequent in patients with AF, as was the proportion of total anterior circulation strokes. Ischemic stroke associated with AF predicted poor outcome at discharge (adjusted OR 1.56; 95%CI 1.24-1.96) and higher mortality rates throughout follow-up. Among patients with a CHADS(2) score ≥ 2 prior to the index stroke and without known contraindications, 41% received anticoagulation. This proportion increased to only 62% after the index stroke, even after excluding patients with severe disability and no significant increase between 2004 and 2007 was detectable. Increasing age, in-hospital infectious complications, and unfavorable functional status at discharge were independently associated with decreased likelihood of receiving anticoagulation.

CONCLUSIONS

In deviation from current recommendations and in spite of the introduction of CHADS(2) criteria, anticoagulation for stroke prevention remains underutilized, despite the particularly poor outcome of strokes associated with AF.

Predicting left atrial thrombi in atrial fibrillation

BACKGROUND

The aim of the study was to determine whether CHADS(2) score is predictive of left atrial appendage thrombus (LAAT) in nonvalvular atrial fibrillation (AF). Strategies for effective stroke prevention in AF require tools capable of identifying those patients at greatest risk for embolization of LAAT and most likely to benefit from warfarin. Nearly half of strokes in AF are due to noncardioembolic mechanisms for which antiplatelet therapy would be more appropriate. Previous attempts to develop such tools have been limited by including patients without proven cardioembolism.

METHODS

Nonanticoagulated, nonvalvular AF patients with (cases) or without (controls) LAAT by transesophageal echocardiography were identified using Mayo Clinic Echocardiography and Cardioversion Unit Databases (Rochester, MN). Type and duration of AF, CHADS(2) score, and echocardiography measures were compared to determine variables predictive of LAAT.

RESULTS

The CHADS(2) score was significantly higher for cases (n = 110, mean +/- SD 2.8 +/- 1.6) compared to controls (n = 387, 1.6 +/- 1.3). By multivariate analysis, independent predictors of LAAT included heart failure (HR 5.78, P < 0001), prior stroke/transient ischemic attack (HR 3.94, P < .0001), diabetes mellitus (HR 1.98, P = .015), permanent AF (HR 3.02, P < .05), AF duration (HR 2.24, P < .05), and spontaneous echocardiographic contrast (HR 4.35, P = .005). Using these elements, a new scoring system provided cleaner case-control separation (C-index 0.90) and higher predictive power compared to CHADS(2) (C-index 0.71).

CONCLUSIONS

The CHADS(2) score predicts the presence of LAAT in AF patients. Some, but not all, variables within this score are predictive of LAAT. By including only echo and clinical variables predictive of LAAT, our novel scoring system better identified those AF patients at greatest cardioembolic risk.

Levels of mint and wintergreen flavorants: smokeless tobacco products vs. confectionery products

Nicotine and flavorant compound levels were measured in 10 "mint"-related sub-brands and 8 "wintergreen" sub-brands of smokeless tobacco (SLT). Also analyzed were "mint"-related and "wintergreen" confectionery products. Of the "mint" SLT, "Timberwolf Packs Mint Pouches" contained the highest menthol level (5.3 mg/g); the average for the five most-highly mentholated SLT products was 4.3 mg/g. The average for the most five most-highly mentholated confectionery products was 3.5 mg/g. For hard candy, a reported average of maximum use levels is 2.1 mg/g (Burdock, 2009). Of the "wintergreen" SLT, "Hawken Wintergreen" was found to contain the highest methyl salicylate (MS) level (29.7 mg/g). The average of the five highest SLT MS levels was 23.8 mg/g, i.e., 5x higher than the level found in the confectionery product with the highest MS level (LifeSavers Wint O Green Sugar Free, 4.6 mg/g). For hard candy, a reported average of maximum use levels is 2.0 mg/g (Burdock, 2009). Assuming 23.8 mg/g MS in SLT, SLT use at 15 g/day, 100% bodily absorption of the MS, and 60 kg body weight, the average daily intake would be 6.0 mg/kg-day, i.e., 12x the acceptable daily intake (ADI) of 0.5 mg/kg-day established for this compound by a joint FAO/WHO committee.

Epidemiology and management of bleeding in patients using vitamin K antagonists

Vitamin K antagonists are effective in the prevention and treatment of a variety of arterial and venous thrombotic disorders, but are associated with an increased risk of serious bleeding complications. According to well documented studies of patients using vitamin K antagonists, the incidence of major bleeding is 0.5% per year and the incidence of intracranial bleeding is 0.2% per year, however, in real life practice this incidence may be even higher. Risk factors for bleeding are the intensity of anticoagulation, the management strategy to keep the INR in the desired range, and patient characteristics. In case of serious bleeding complications in a patient who uses vitamin K antagonists, this anticoagulant treatment can be quickly reversed by administration of vitamin K or coagulation factor concentrates.

Contemporary management of atrial fibrillation: update on anticoagulation and invasive management strategies

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice. Its increasing prevalence, particularly among the elderly, renders it one of the most serious current medical epidemics. Several management questions confront the clinician treating a patient with AF: Should the condition be treated? Is the patient at risk of death or serious morbidity as a result of this diagnosis? If treatment is necessary, is rate control or rhythm control superior? Which patients need anticoagulation therapy, and for how long? This review of articles obtained by a search of the PubMed and MEDLINE databases presents the available evidence that can guide the clinician in answering these questions. After discussing the merits of available therapy, including medications aimed at controlling rate, rhythm, or both, we focus on the present status of ablative therapy for AF. Catheter ablation, particularly targeting the pulmonary veins, is being increasingly performed, although the precise indications for this approach and its effectiveness and safety are being actively investigated. We briefly discuss other invasive options that are less frequently used, such as pacemakers, defibrillators, left atrial appendage closure devices, and the surgical maze procedure.

New anticoagulants for atrial fibrillation

Although warfarin and other vitamin K antagonists have clearly the greatest efficacy among treatments commonly available in preventing stroke in atrial fibrillation, their use is associated with a substantial risk of major bleedings and are unpractical and difficult to use because of their narrow therapeutic window, their interaction with drugs and foods, and the need of frequent coagulation monitoring. Several new anticoagulants are now undergoing phase III clinical trials in atrial fibrillation with the aim of demonstrating noninferiority compared with vitamin K antagonists or superiority compared with aspirin in patients in whom vitamin K antagonists are contraindicated or not tolerated. These drugs fall in different pharmacological categories of oral direct thrombin inhibitors, parenteral long-lived indirect factor Xa inhibitors, and oral direct factor Xa inhibitors. Cardiologists need to be aware of the explosive pharmacological literature being accrued with these new drugs, as most of these will likely enter the clinical arena in the near future.