Anticoagulation in atrial fibrillation: selected controversies including optimal anticoagulation intensity, treatment of intracerebral hemorrhage

Meta-Analysis of Efficacy and Safety of Low-Intensity Warfarin Therapy for East Asian Patients With Nonvalvular Atrial Fibrillation

For patients with nonvalvular atrial fibrillation (NVAF) receiving warfarin therapy, the target international normalized ratio range of 2.0 to 3.0 is recommended by Western countries. However, this treatment carries a higher risk of bleeding which suggests more researches on whether low-intensity warfarin therapy (range <2.0 to 3.0) is suitable for East Asian patients. Three databases were searched from inception to April 21, 2016. Studies that reported thromboembolic and hemorrhagic events in low- and standard-intensity warfarin groups were included. Finally, seven studies were included in the analysis. There was a significantly decreased risk of hemorrhagic events (odds ratio [OR] 0.59, 95% confidence interval [CI] 0.43 to 0.82, p = 0.002) with no statistically increased risk of thromboembolic events (OR 1.14, 95% CI 0.80 to 1.62, p = 0.47) in the 1.5 to 2.0 group compared with that of the 2.0 to 3.0 group. Meanwhile, there was no significant difference of cardiovascular mortality (OR 1.58, 95% CI 0.89 to 2.83, p = 0.12) between the 2 groups. Further analysis showed there was no significance in thromboembolic events (OR 1.15, 95% CI 0.83 to 1.60, p = 0.40), major bleeding events (OR 0.74, 95% CI 0.50 to 1.09, p = 0.13), and cardiovascular mortality (OR 1.45, 95% CI 0.79 to 2.65, p = 0.23) between 1.5 to 2.5 and 2.0 to 3.0 groups. Although no significant difference was found in hemorrhagic events (OR 0.76, 95% CI 0.57 to 1.01, p = 0.06), there was a decreased trend in it. In conclusion, low-intensity warfarin therapy can achieve reduced hemorrhage without increasing thromboembolism for East Asian patients with NVAF receiving warfarin therapy.

Antithrombotic drug uses and deep intracerebral hemorrhages in stroke patients with deep cerebral microbleeds

BACKGROUND

It has been suggested that antiplatelet or anticoagulant drugs elevate the rate of intracerebral hemorrhage (ICH) in patients with cerebral microbleeds (MBs). To investigate the mechanism by which antiplatelet drugs or warfarin may contribute to deep ICH occurrences in patients with deep MBs, we prospectively analyzed deep ICH occurrences in 807 consecutive patients (351 females and 456 males; mean age ± standard deviation 69.8 ± 12.0 years) who were admitted to our hospital with strokes.

METHODS

Occurrence-free rate curves were generated using the Kaplan-Meier method; deep ICH occurrence-free rates were compared using the log-rank test. The follow-up period was 0.5 to 71 months (mean ± standard deviation 31.6 ± 22.2 months).

RESULTS

In patients with deep MBs, the rates (1.0%/year; 6 ICHs in 180 patients) of deep ICH occurrence associated with antiplatelet drugs were not significantly greater than that without the drugs (1.0%/year; 6 ICHs in 167 patients; P = .977). The incidence of deep ICHs associated with warfarin use was not significantly greater than that without warfarin use.

CONCLUSIONS

Multivariate analysis revealed that the use of antiplatelet drugs or warfarin did not significantly influence the occurrence of deep ICH in patients with deep MBs. Antiplatelet drugs or warfarin did not significantly elevate the rate of deep ICHs in stroke patients with pre-existing deep MBs.

[Prevention of cardioembolic stroke]

Stroke and atrial fibrillation (AF) constitute a true vascular epidemic with catastrophic consequences. The most common and devastating complication of AF is cardioembolic stroke but this catastrophic event can be predicted and prevented. Accurate etiologic diagnosis of stroke is essential for effective prevention. The percentage of cryptogenic ischemic strokes is too high and detection of AF and other causes of cardioembolic events should be improved. Cardioembolic cerebral ischemia can be prevented. However, because of physician inertia, lack of patient adherence and the problems of vitamin K antagonists, many patients are at risk of cerebral ischemia. Recently, major advances with drugs such as dronedarone, dabigatran and FXa inhibitors have opened the way to improving stroke prevention, as reflected in therapeutic guidelines, and neurologists should be familiar with these drugs. There is reason to hope that much suffering can be avoided.

Early complications of ischemic stroke

Patients with acute ischemic stroke are at high risk of neurologic and medical complications, such as space-occupying edema formation, hemorrhagic transformation of the infarct, epileptic seizures, depression, and venous thromboembolism. They should therefore be monitored closely for early detection of these complications. Care is best when the patient is admitted to a specialized stroke unit. The multidisciplinary approach provided by stroke units, including specialized medical, nursing, and remedial therapies, reduces the duration of hospitalization and improves functional outcome. For many complications, however, optimal treatment and its effect on functional outcome after stroke has not been established. Therefore, in addition to the ongoing acute intervention trials, well-designed, large randomized trials are needed to address the prevention and treatment of complications and their effect on functional outcome.

Treatments for reversing warfarin anticoagulation in patients with acute intracranial hemorrhage: a structured literature review

Study objective

The acute management of patients on warfarin with spontaneous or traumatic intracranial hemorrhage continues to be debated in the medical literature. The objective of this paper was to conduct a structured review of the medical literature and summarize the advantages and risks of the available treatment options for reversing warfarin anticoagulation in patients who present to the emergency department with acute intracranial hemorrhage.

Methods

A structured literature search and review of articles relevant to intracranial hemorrhage and warfarin and treatment in the emergency department was performed. Databases for PubMed, CINAHL, and Cochrane EBM Reviews were electronically searched using keywords covering the concepts of anticoagulation drugs, intracranial hemorrhage (ICH), and treatment. The results generated by the search were limited to English- language articles and reviewed for relevance to our topic. The multiple database searches revealed 586 papers for review for possible inclusion. The final consensus of our comprehensive search strategy was a total of 23 original studies for inclusion in our review.

Results

Warfarin not only increases the risk of but also the severity of ICH by causing hematoma expansion. Prothrombin complex concentrate is statistically significantly faster at correcting the INR compared to fresh frozen plasma transfusions. Recombinant factor VIIa appears to rapidly reverse warfarin's effect on INR; however, this treatment is not FDA-approved and is associated with a 5% thromboembolic event rate. Slow intravenous dosing of vitamin K is recommended in patients with ICH. The 30-day risk for ischemic stroke after discontinuation of warfarin therapy was 3-5%. The risks of not reversing the anticoagulation in ICH generally outweigh the risk of thrombosis in the acute setting.

Conclusions

Increasing numbers of patients are on anticoagulation including warfarin. There is no uniform standard for reversing warfarin in intracranial hemorrhage. Intravenous vitamin K in addition to fresh frozen plasma or prothrombin complex concentrate is recommended be used to reverse warfarin-associated intracranial hemorrhage. No mortality benefit for one treatment regimen over another has been shown. Emergency physicians should know their hospital's available warfarin reversal options and be comfortable administering these treatments to critically ill patients.

[Persistent left atrial thrombus in atrial fibrillation under oral anticoagulation]

The case of a 78-year-old female patient who suffered atrial fibrillation and persistent thrombus in the left atrial appendage despite sufficient anticoagulation is reported. The case is chosen to demonstrate the complexity inherent in prophylaxis as well as risk evaluation of thromboembolism on the basis of clinical and echocardiographic criteria. We also discuss transesophageal echocardiography as the standard diagnostic procedure for detection of intracardiac thrombi prior to cardioversion as well as cardiac computer tomography as an alternative.

Optimizing warfarin reversal--an ex vivo study

BACKGROUND

Warfarin reversal is a common clinical situation. This is commonly performed using vitamin K and, depending on the urgency, fresh frozen plasma (FFP), prothrombin complex concentrates (PCCs), or activated factor VII. Even though PCCs are widely used, the ideal dosing regimen is far from established.

OBJECTIVES

To verify differences in warfarin reversal patterns using FFP, recombinant FVIIa (rFVIIa), and PCC; and to test the hypothesis that supratherapeutic International Normalized Ratios (INRs) might not correlate with thrombin generation (TG) and identify the ideal concentrations of PCC required to reverse various INR thresholds.

METHODS

We studied the effects of FFP, rFVIIa and Beriplex P/N on the INR and TG, using the calibrated automated thrombography assay in ex vivo warfarinized plasma. Plasmas with different INRs were spiked with different concentrations of Beriplex P/N.

RESULTS

Beriplex P/N was the only agent that completely normalized TG and the INR. The endogenous thrombin potential (ETP) and the peak thrombin showed a significant negative correlation with all INRs. The ETP and velocity of TG reached a plateau at an INR of approximately 4.0. A concentration equivalent to a dose of 30 IU kg(-1) Beriplex P/N normalized the ETP, the INR, FII, FVII, FIX and FX of samples with INRs > or = 4.0. Higher doses resulted in hypercoagulable TG patterns. A concentration equivalent to a dose of 20 IU kg(-1) was sufficient to reverse warfarin at an INR range of 2.0-3.9, as judged by the same tests.

CONCLUSIONS

Warfarin reversal algorithms could be simplified with the adoption of this strategy utilizing two doses of PCC, depending on the INR of the patient. This would also lead to cost reductions and, possibly, a reduction in thrombotic risk.

Warfarin reversal in anticoagulant-associated intracerebral hemorrhage

Anticoagulant-associated intracerebral hemorrhage (ICH) is a devastating disease, causing death in half of patients and permanent disability in the majority of survivors. The finding that patients often continue bleeding after hospital presentation offers the possibility that emergency warfarin reversal may improve outcomes. As no clinical trials have demonstrated the superiority of any one treatment strategy, various treatment options are available. Intravenous vitamin K is the definitive therapy; however, as monotherapy it can require many hours to take effect. Therefore, it is often considered an adjunct agent. Coagulation factors can be repleted with fresh frozen plasma (FFP), which is widely available and relatively low cost, but can require substantial time to deliver in real-world settings. A number of coagulation factor products collectively termed prothrombin complex concentrates (PCCs) are widely available that can rapidly provide many or all the vitamin K-dependent coagulation factors. Recombinant activated factor VII is used in many centers for this purpose, as it is thought to provide a procoagulant effect that may compensate for the lack of the other critical factors. Until clinical trials demonstrate the superiority of any one means of warfarin reversal, a number of expert guidelines from national organizations are available to help local providers guide therapy. At our institution, we have focused on improving the rapid and reliable delivery of a combination of intravenous vitamin K and FFP, with continued re-dosing until the desired INR lowering is achieved.

Anticoagulation in atrial fibrillation: the trials and tribulations of keeping within therapeutic range

Atrial fibrillation (AF) is a growing epidemic in the developed world that has attracted much attention due to the associated risk of stroke and thromboembolism. This article discusses the application of oral anticoagulation (OAC) therapy with vitamin K antagonists (VKA) in order to reduce these risks. The article provides an overview of OAC management and highlights the need for greater efforts to increase time within therapeutic range.