Coagulation Testing in Acute Ischemic Stroke Patients Taking Non–Vitamin K Antagonist Oral Anticoagulants

Direct oral anticoagulants or vitamin K antagonists in emergencies: comparison of management in an observational study

Background

Restoring hemostasis in patients on oral anticoagulants presenting with major hemorrhage (MH) or before surgical intervention has changed, with the replacement of vitamin K antagonist (VKA) with direct oral anticoagulants (DOACs).

Objectives

To observe the difference in urgent hemostatic management between patients on VKA and those on DOACs.

Methods

A multicenter observational study evaluated the variation in laboratory testing, hemostatic management, mortality, and hospital length of stay (LOS) in patients on VKA or DOACs presenting with MH or urgent hemostatic restoration.

Results

Of the 1194 patients analyzed, 783 had MH (61% VKA) and 411 required urgent hemostatic restoration before surgery (56% VKA). Compared to the international normalized ratio (97.6%), plasma DOAC levels were measured less frequently (<45%), and the time taken from admission for the coagulation sample to reach the laboratory varied widely (median, 52.3 minutes; IQR, 24.8-206.7). No significant plasma DOAC level (<50 ng/mL) was found in up to 19% of patients. There was a poor relationship between plasma DOAC level and the usage of a hemostatic agent. When compared with patients receiving VKA (96.5%) or dabigatran (93.7%), fewer patients prescribed a factor Xa inhibitor (75.5%) received a prohemostatic reversal agent. The overall 30-day mortality for MH (mean: 17.8%) and length of stay (LOS) (median: 8.7 days) was similar between VKA and DOAC patients.

Conclusion

In DOAC patients, when compared to those receiving VKA, plasma DOAC levels were measured less frequently than the international normalized ratio and had a poor relationship with administering a hemostatic reversal agent. In addition, following MH, mortality and LOS were similar between VKA and DOAC patients.

Global Coagulation Testing in Acute Care Medicine: Back to Bedside?

OBJECTIVES

 Detailed and decisive information about the patients' coagulation status is important in various emergency situations. Conventional global coagulation testing strategies are often used to provide a quick overview, but several limitations particularly in the trauma setting are well described. With the introduction of direct oral anticoagulations (DOACs), a milestone for several disease entities resulting in overall improved outcomes could be reached, but at the same time providing new diagnostic challenges for the emergency situation.

DESIGN

 As an alternative to conventional coagulation tests, there is increasing clinical and scientific interest in the use of early whole blood strategies to provide goal-directed coagulation therapies (GDCT) and hemostatic control in critically ill patients. Viscoelastic hemostatic assays (VHAs) were therefore introduced to several clinical applications and may provide as a bedside point-of-care method for faster information on the underlying hemostatic deficiency.

CONCLUSION

 The use of VHA-based algorithms to guide hemostatic control in emergency situations now found its way to several international guidelines for patients at risk of bleeding. With this qualitative review, we would like to focus on VHA-based GDCT and review the current evidence for its use, advantages, and challenges in the two different clinical scenarios of trauma and intracerebral bleeding/stroke management.

Association Between Inappropriately Dosed Anticoagulation Therapy With Stroke Severity and Outcomes in Patients With Atrial Fibrillation

Background

Oral anticoagulation (OAC) is effective for stroke prevention in patients with atrial fibrillation. However, some patients experience stroke despite OAC therapy, and knowledge about the impact of prior treatment quality is lacking.

Methods and Results

Patients with atrial fibrillation on OAC therapy who had a first‐time ischemic stroke were identified in the Danish Stroke Registry (2005–2018). Patients treated with vitamin K antagonist (VKA) therapy were compared according to the international normalized ratio just before stroke (international normalized ratio <2 [subtherapeutic], international normalized ratio 2–3 [therapeutic], international normalized ratio >3 [supratherapeutic]), and patients on underdosed, appropriately dosed, and overdosed direct OAC (DOAC) therapy were compared. Stroke severity was determined using the Scandinavia Stroke Scale (0–58 points), and the risk of very severe stroke (0–14 points) was analyzed by multivariable logistic regression. One‐year mortality was determined using multivariable Cox regression. A total of 2319 patients with atrial fibrillation and stroke were included; 1196 were taking a VKA (subtherapeutic [46%], therapeutic [43%], supratherapeutic [11%]), and 1123 were taking DOAC (underdosed [23%], appropriately dosed [60%], and overdosed [17%]). Subtherapeutic and supratherapeutic VKA therapy (compared with therapeutic) and underdosed DOAC therapy (compared with appropriate and underdosed DOAC) patients were older, more often women, and more comorbid. Subtherapeutic VKA therapy was associated with very severe stroke (odds ratio [OR], 2.06 [95% CI, 1.28–3.31]), whereas supratherapeutic VKA therapy was not (OR, 1.24 [95% CI, 0.60–2.57]) compared with therapeutic VKA therapy. Patients on subtherapeutic and supratherapeutic VKA therapy had a higher 1‐year mortality (hazard ratio [HR], 1.66 [95% CI, 1.29–2.13]); HR, 1.55 [95% CI, 1.08–2.22], respectively) than those on therapeutic VKA therapy. Treatment with underdosed or overdosed DOAC therapy was not associated with very severe stroke (OR, 1.27 [95% CI, 0.76–2.15]; OR, 0.73 [95% CI, 0.37–1.43], respectively) and was not associated with 1‐year mortality (HR, 1.09 [95% CI, 0.83–1.44]; HR, 0.82 [95% CI, 0.57–1.18], respectively) than appropriate DOAC.

Conclusions

Half of the patients with atrial fibrillation with stroke were on inappropriate OAC therapy. Subtherapeutic VKA was associated with worse stroke severity and higher mortality rate than therapeutic VKA therapy. Neither underdosed nor overdosed DOAC was associated with worse outcomes in adjusted models compared with appropriately dosed DOAC. This study supports DOAC as a first‐line therapy over VKA.

Low Exposure to Direct Oral Anticoagulants Is Associated with Ischemic Stroke and Its Severity

Background and purpose

In acute stroke patients, plasma concentrations of direct oral anticoagulants (DOAC) at hospital admission only poorly mirror DOAC exposure or the coagulation status at the time of the event. Here, we evaluated whether DOAC exposure and DOAC plasma concentration at the time of transient ischemic attacks (TIA) and ischemic strokes correlate with their likelihood of occurrence.

Methods

Prospectively, consecutive DOAC patients with acute ischemic stroke or TIA were included. Admission DOAC plasma concentrations were measured by ultraperformance liquid chromatography– tandem mass spectrometry. Individual DOAC exposure (area under the curve) and DOAC concentrations at event onset were derived from population pharmacokinetic analyses.

Results

DOAC exposure was successfully modeled in 211 patients (ischemic stroke 74.4%, TIA 25.6%). Compared to published values, 63.0% had relatively lower DOAC exposure and they more often received lower DOAC doses than recommended (odds ratio [OR], 2.125; 95% confidence interval [CI], 1.039 to 4.560; P=0.044). These patients more likely suffered ischemic strokes than TIA (OR, 2.411; 95% CI, 1.254 to 4.638; P=0.008) and their strokes were more severe (slope, 3.161; 95% CI, 0.741 to 5.58; P=0.011). Low relative DOAC concentrations at event onset were likewise associated with ischemic strokes (OR, 4.123; 95% CI, 1.834 to 9.268; P=0.001), but not to stroke severity (P=0.272). DOAC exposure had a higher explanatory value for stroke severity than concentrations at event.

Conclusions

Low DOAC exposure is strongly associated to ischemic stroke and its severity. By monitoring DOAC plasma concentrations, patients prone to ischemic stroke might be identified.

Acute Stroke Treatment in an Anticoagulated Patient: When Is Thrombolysis an Option?

Purpose of Review

Direct oral anticoagulants (DOACs: the factor Xa inhibitors rivaroxaban, apixaban, and edoxaban and the direct thrombin inhibitor dabigatran) are the mainstay of stroke prevention in patients with non-valvular atrial fibrillation (AF). Nevertheless, there is a residual stroke risk of 1–2% per year despite DOAC therapy. Intravenous thrombolysis (IVT) reduces morbidity in patients with ischemic stroke and improves functional outcome. Prior DOAC therapy is a (relative) contraindication for IVT but emerging evidence supports its use in selected patients.

Recent Findings

Recent observational studies highlighted that IVT in patients on prior DOAC therapy seems feasible and did not yield major safety issues. Different selection criteria and approaches have been studied including selection by DOAC plasma levels, non-specific coagulation assays, time since last intake, and prior reversal agent use. The optimal selection process is however not clear and most studies comprised few patients.

Summary

IVT in patients taking DOAC is a clinically challenging scenario. Several approaches have been proposed without major safety issues but current evidence is weak. A patient-oriented approach balancing potential benefits of IVT (i.e., amount of salvageable penumbra) against expected bleeding risk including appropriate monitoring of anticoagulant activity seem justified.

Challenges of Acute Ischemic Stroke Treatment in Orally Anticoagulated Patients via Telemedicine

Background: Managing acute ischemic stroke (AIS) in patients receiving treatment with vitamin K antagonists (VKA) or non-VKA oral anticoagulants (NOACs) is difficult and the challenge this poses for stroke telemedicine remains unexplored. Methods: We analyzed data from a random sample (n = 1500) of all teleneurological consultations conducted between July 2015 and December 2017. Management of patients suffering AIS with and without prior oral anticoagulation treatment was characterized, including potential vs. actual treatment with intravenous thrombolysis (IVT) and reasons for withholding it. Results: n = 359 patients had suffered an AIS, of whom 63 (17.5%) were under treatment with oral anticoagulants (VKA, n = 24; NOAC, n = 39). Administration of IVT was more common in patients who had not received prior oral anticoagulation treatment (20.3% vs. 3.2%, p < 0.001). NOAC intake was the primary reason for withholding IVT in 37% of orally anticoagulated patients who were found potentially eligible for IVT. Furthermore, patients under oral anticoagulation tended to be transported to the comprehensive stroke center more often (23.8% vs. 13.9%, p = 0.056). Conclusions: AIS in patients on oral anticoagulation treatment is a frequent reason for telestroke consultation, and NOAC intake constitutes an important barrier to administering IVT.

Recanalisation therapies for acute ischaemic stroke in patients on direct oral anticoagulants

Direct oral anticoagulants (DOACs) have emerged as primary therapeutic option for stroke prevention in patients with atrial fibrillation. However, patients may have ischaemic stroke despite DOAC therapy and there is uncertainty whether those patients can safely receive intravenous thrombolysis or mechanical thrombectomy. In this review, we summarise and discuss current knowledge about different approaches to select patient. Time since last DOAC intake-as a surrogate for anticoagulant activity-is easy to use but limited by interindividual variability of drug pharmacokinetics and long cut-offs (>48 hours). Measuring anticoagulant activity using drug-specific coagulation assays showed promising safety results. Large proportion of patients at low anticoagulant activity seem to be potentially treatable but there remains uncertainty about exact safe cut-off values and limited assay availability. The use of specific reversal agents (ie, idarucizumab or andexanet alfa) prior to thrombolysis is a new emerging option with first data reporting safety but issues including health economics need to be elucidated. Mechanical thrombectomy appears to be safe without any specific selection criteria applied. In patients on DOAC therapy with large vessel occlusion, decision for intravenous thrombolysis should not delay thrombectomy (eg, direct thrombectomy or immediate transfer to a thrombectomy-capable centre recommended). Precision medicine using a tailored approach combining clinicoradiological information (ie, penumbra and vessel status), anticoagulant activity and use of specific reversal agents only if necessary seems a reasonable choice.

Coagulation Assay and Stroke Severity upon Admission of Patients with Cardioembolic Cerebral Infarction during Direct Oral Anticoagulant Use

Although the severity of acute cerebral infarction varies in patients receiving direct oral anticoagulants (DOACs), no practical method to predict the severity has been established. We analyzed retrospectively the relationship between cardioembolic cerebral infarction severity and coagulation indicators in patients treated with DOACs. We assessed the anticoagulation effect of DOACs using the activated partial thromboplastin time (APTT), prothrombin time (PT), and prothrombin time international standardized ratio (PT-INR) in 71 patients with cardioembolic cerebral infarction admitted to our hospital between January 2015 and December 2019. The participants were divided into a prolongation group (prolonged APTT for oral thrombin inhibitors or prolonged PT for oral factor Xa inhibitors, n =37) and a normal group (no prolongation of coagulation markers, n =34). Of the 71 patients, 21 (30%) and 50 (70%) were using oral thrombin and oral factor Xa inhibitors, respectively. PT, PT-INR, and APTT were significantly higher in the prolongation group (PT: 17.4 ± 5.1 vs. 12.8 ± 1.4 s, P < 0.001; PT-INR: 1.5 ± 0.5 vs. 1.1 ± 0.1, P < 0.001; APTT: 44.8 ± 26.4 vs. 30.4 ± 4.1 s, P = 0.003). The median National Institutes of Health Stroke Scale (NIHSS) score on admission and the prevalence of large vessel occlusion were significantly lower in the prolongation group (NIHSS: 2.0 vs. 9.5, P = 0.007; large vessel occlusion: 27% vs. 53%, P = 0.031). The prevalence of large vessel occlusion was low and stroke severity was mild in patients undergoing DOAC therapy with prolongation of coagulation assay markers upon onset of cardioembolic cerebral infarction.

Point-of-care testing for emergency assessment of coagulation in patients treated with direct oral anticoagulants including edoxaban

Background

Direct oral anticoagulants (DOAC) including edoxaban are increasingly used for stroke prevention in atrial fibrillation. Despite treatment, annual stroke rate in these patients remains 1–2%. Rapid assessment of coagulation would be useful to guide thrombolysis or reversal therapy in this growing population of DOAC/edoxaban-treated stroke patients. Employing the Hemochron™ Signature Elite point-of-care test system (HC-POCT), clinically relevant plasma concentrations of dabigatran and rivaroxaban can be excluded in a blood sample. However, no data exists on the effect of edoxaban on HC-POCT results.

We evaluated whether edoxaban plasma concentrations above the current treatment thresholds for thrombolysis or anticoagulation reversal (i.e., 30 and 50 ng/mL) can be ruled out with the HC-POCT.

Methods

We prospectively studied patients receiving a first dose of edoxaban. Six blood samples were collected from each patient: before, 0.5, 1, 2, 8, and 24 h after drug intake. HC-POCT-based INR (HC-INR), activated clotting time (HC-ACT+ and HC-ACT-LR), activated partial thromboplastin time (HC-aPTT), and mass spectrometry for edoxaban plasma concentrations were performed at each time-point. We calculated correlations, receiver operating characteristics (ROC) and test-specific cut-offs for ruling out edoxaban concentrations > 30 and > 50 ng/mL in a blood sample.

Results

One hundred twenty blood samples from 20 edoxaban-treated patients were analyzed. Edoxaban plasma concentrations ranged from 0 to 512 ng/mL. HC-INR/HC-ACT+/HC-ACT-LR/HC-aPTT ranged from 0.7–8.3/78–310 s/65–215 s/19–93 s, and Pearson’s correlation coefficients showed moderate to very strong correlations with edoxaban concentrations (r = 0.95/0.79/0.70/0.60). With areas under the ROC curve of 0.997 (95% confidence interval: 0.991–0.971) and 0.989 (0.975–1.000), HC-INR most reliably ruled out edoxaban concentrations > 30 and > 50 ng/mL, respectively, and HC-INR results ≤1.5 and ≤ 2.1 provided specificity/sensitivity of 98.6% (91.2–99.9)/98.0% (88.0–99.9) and 96.8% (88.0–99.4)/96.5% (86.8–99.4).

Conclusions

Our study represents the first systematic evaluation of the HC-POCT in edoxaban-treated patients. Applying sufficiently low assay-specific cut-offs, the HC-POCT may not only be used to reliably rule out dabigatran and rivaroxaban, but also very low edoxaban concentrations in a blood sample. Because the assay-specific cut-offs were retrospectively defined, further investigation is warranted.

Trial registration

ClinicalTrials.gov, registration number: NCT02825394, registered on: 07/07/2016, URL

Supplementary Information

The online version contains supplementary material available at 10.1186/s42466-021-00105-4.

Direct Oral Anticoagulants Plasma Levels Measurement: Clinical Usefulness from Trials and Real-World Data

Measurement of direct oral anticoagulants (DOACs) activity is not routinely necessary. Indeed, evaluation of DOACs plasmatic concentration is discouraged for the majority of patients, due to the lack of outcome data supporting this approach. Nevertheless, DOAC measurements may be useful in emergency situations such as serious bleeding events, need for urgent invasive procedures, and acute ischemic stroke or in managing anticoagulation in "special populations" not adequately studied in clinical trials, for example the very elderly or those at the extremes of body weight. The aim of this review is to describe and summarize the methods for DOACs activity evaluation and the settings in which their plasma level measurement may be indicated, analyzing indications from scientific societies and evidence from clinical trials, as well as real world data on the usefulness of DOACs plasma levels "monitoring."

Prior Anticoagulation in Patients with Ischemic Stroke and Atrial Fibrillation

OBJECTIVE

The aim was to evaluate, in patients with atrial fibrillation (AF) and acute ischemic stroke, the association of prior anticoagulation with vitamin K antagonists (VKAs) or direct oral anticoagulants (DOACs) with stroke severity, utilization of intravenous thrombolysis (IVT), safety of IVT, and 3-month outcomes.

METHODS

This was a cohort study of consecutive patients (2014-2019) on anticoagulation versus those without (controls) with regard to stroke severity, rates of IVT/mechanical thrombectomy, symptomatic intracranial hemorrhage (sICH), and favorable outcome (modified Rankin Scale score 0-2) at 3 months.

RESULTS

Of 8,179 patients (mean [SD] age, 79.8 [9.6] years; 49% women), 1,486 (18%) were on VKA treatment, 1,634 (20%) on DOAC treatment at stroke onset, and 5,059 controls. Stroke severity was lower in patients on DOACs (median National Institutes of Health Stroke Scale 4, [interquartile range 2-11]) compared with VKA (6, [2-14]) and controls (7, [3-15], p < 0.001; quantile regression: β -2.1, 95% confidence interval [CI] -2.6 to -1.7). The IVT rate in potentially eligible patients was significantly lower in patients on VKA (156 of 247 [63%]; adjusted odds ratio [aOR] 0.67; 95% CI 0.50-0.90) and particularly in patients on DOACs (69 of 464 [15%]; aOR 0.06; 95% CI 0.05-0.08) compared with controls (1,544 of 2,504 [74%]). sICH after IVT occurred in 3.6% (2.6-4.7%) of controls, 9 of 195 (4.6%; 1.9-9.2%; aOR 0.93; 95% CI 0.46-1.90) patients on VKA and 2 of 65 (3.1%; 0.4-10.8%, aOR 0.56; 95% CI 0.28-1.12) of those on DOACs. After adjustments for prognostic confounders, DOAC pretreatment was associated with a favorable 3-month outcome (aOR 1.24; 1.01-1.51).

INTERPRETATION

Prior DOAC therapy in patients with AF was associated with decreased admission stroke severity at onset and a remarkably low rate of IVT. Overall, patients on DOAC might have better functional outcome at 3 months. Further research is needed to overcome potential restrictions for IVT in patients taking DOACs. ANN NEUROL 2021;89:42-53.

Effects of dabigatran and rivaroxaban on stroke severity according to the results of routine coagulation tests

Introduction

Prior use of direct oral anticoagulants has been associated with reduced stroke severity in patients with non-valvular atrial fibrillation (NVAF). The aim of this study was to investigate the impact of prothrombin time (PT) and activated partial thromboplastin time (aPTT) on stroke severity in patients who were receiving dabigatran or rivaroxaban at the time of stroke onset.

Materials and methods

We enrolled 107 patients with NVAF who developed acute ischemic stroke while on dabigatran or rivaroxaban and presented within 24 hours to nine hospitals between January 2014 and December 2018. The results of PT and aPTT assays were obtained within 24 hours of stroke onset in all patients. We analyzed PT and aPTT in relation to stroke severity and ischemic lesion volume using correlation and multivariable regression analyses.

Results

Of the 107 patients included, 46 (43.0%) were on dabigatran and 61 (57.0%) were on rivaroxaban. In patients with prior dabigatran use, while aPTT was inversely correlated with admission National Institutes of Health Stroke Scale (NIHSS) score (r = -0.369, p = 0.012) and ischemic lesion volume (r = -0.480, p = 0.005), there was no correlation between PT and either of these variables. Multivariable analysis confirmed the existence of a significant independent inverse relationship between aPTT and NIHSS score at admission (B, -0.201; 95% confidence interval [CI], -0.370 to -0.032; p = 0.005) and between aPTT and ischemic lesion volume (B, -0.076; 95% CI, -0.130 to -0.023; p = 0.007). In patients with prior rivaroxaban use, neither PT nor aPTT was associated with admission NIHSS score or ischemic lesion volume in the correlation and multivariable analyses.

Conclusions

In patients with NVAF who were receiving dabigatran, prolonged aPTT was associated with reduced stroke severity.

Etiology of Ischemic Strokes of Patients with Atrial Fibrillation and Therapy with Anticoagulants

BACKGROUND

Reducing the number of ischemic strokes in patients with atrial fibrillation despite oral anticoagulation remains an important, yet largely unsolved challenge. Therefore, we assessed the etiology of ischemic strokes despite anticoagulation with vitamin K antagonists (VKA) or non-VKA oral anticoagulants (NOACs).

METHODS

Patients with known atrial fibrillation (AF), treatment with VKA or NOAC, and acute ischemic stroke admitted between 2015 and 2018 (1st half) were identified from the hospital database. Brain imaging data were independently reviewed. An integrated etiologic classification according to the ASCOD system was made. Medication errors (admission INR <2.0 in the VKA- or NOAC-specific concentration <10 ng/mL) or dosage/dosing errors were also analyzed.

RESULTS

Of 3610 patients screened, n = 341 were included (VKA, n = 127; NOAC, n = 214). An overall increasing rate of OAC-associated stroke per year was observed. In 95.3% of patients with adequate diagnostic work-up (n = 321/337), at least one additional potential, uncertain, or unlikely non-cardiac cause of stroke was identified. More patients in the VKA than in the NOAC group had a medication error (81/127, 63.8% vs. 102/205, 49.8%; p = 0.013).

CONCLUSIONS

Stroke risk factors despite atrial fibrillation were highly prevalent. Although less common with NOACs than VKAs, medication errors are still frequent.

Antagonizing dabigatran by idarucizumab in cases of ischemic stroke or intracranial hemorrhage in Germany-Updated series of 120 cases

BACKGROUND

Idarucizumab is a monoclonal antibody fragment with high affinity for dabigatran reversing its anticoagulant effects within minutes. Thereby, patients with acute ischemic stroke who are on dabigatran treatment may become eligible for thrombolysis with recombinant tissue-type plasminogen activator (rt-PA). In patients on dabigatran with intracerebral hemorrhage idarucizumab could prevent lesion growth.

AIMS

To provide insights into the clinical use of idarucizumab in patients under effective dabigatran anticoagulation presenting with signs of acute ischemic stroke or intracranial hemorrhage.

METHODS

Retrospective data collected from German neurological/neurosurgical departments administering idarucizumab following product launch from January 2016 to August 2018 were used.

RESULTS

One-hundred and twenty stroke patients received idarucizumab in 61 stroke centers. Eighty patients treated with dabigatran presented with ischemic stroke and 40 patients suffered intracranial bleeding (intracerebral hemorrhage (ICH) in n = 27). In patients receiving intravenous thrombolysis with rt-PA following idarucizumab, 78% showed a median improvement of 7 points in National Institutes of Health Stroke Scale. No bleeding complications were reported. Hematoma growth was observed in 3 out of 27 patients with ICH. Outcome was favorable with a median National Institutes of Health Stroke Scale improvement of 4 points and modified Rankin score 0-3 in 61%. Six out of 40 individuals (15%) with intracranial bleeding died during hospital stay.

CONCLUSION

Administration of rt-PA after reversal of dabigatran activity with idarucizumab in case of acute ischemic stroke seems feasible, effective, and safe. In dabigatran-associated intracranial hemorrhage, idarucizumab appears to prevent hematoma growth and to improve outcome.

The 2018 European Heart Rhythm Association Practical Guide on the use of non-vitamin K antagonist oral anticoagulants in patients with atrial fibrillation

The current manuscript is the second update of the original Practical Guide, published in 2013 [Heidbuchel et al. European Heart Rhythm Association Practical Guide on the use of new oral anticoagulants in patients with non-valvular atrial fibrillation. Europace 2013;15:625-651; Heidbuchel et al. Updated European Heart Rhythm Association Practical Guide on the use of non-vitamin K antagonist anticoagulants in patients with non-valvular atrial fibrillation. Europace 2015;17:1467-1507]. Non-vitamin K antagonist oral anticoagulants (NOACs) are an alternative for vitamin K antagonists (VKAs) to prevent stroke in patients with atrial fibrillation (AF) and have emerged as the preferred choice, particularly in patients newly started on anticoagulation. Both physicians and patients are becoming more accustomed to the use of these drugs in clinical practice. However, many unresolved questions on how to optimally use these agents in specific clinical situations remain. The European Heart Rhythm Association (EHRA) set out to coordinate a unified way of informing physicians on the use of the different NOACs. A writing group identified 20 topics of concrete clinical scenarios for which practical answers were formulated, based on available evidence. The 20 topics are as follows i.e., (1) Eligibility for NOACs; (2) Practical start-up and follow-up scheme for patients on NOACs; (3) Ensuring adherence to prescribed oral anticoagulant intake; (4) Switching between anticoagulant regimens; (5) Pharmacokinetics and drug-drug interactions of NOACs; (6) NOACs in patients with chronic kidney or advanced liver disease; (7) How to measure the anticoagulant effect of NOACs; (8) NOAC plasma level measurement: rare indications, precautions, and potential pitfalls; (9) How to deal with dosing errors; (10) What to do if there is a (suspected) overdose without bleeding, or a clotting test is indicating a potential risk of bleeding; (11) Management of bleeding under NOAC therapy; (12) Patients undergoing a planned invasive procedure, surgery or ablation; (13) Patients requiring an urgent surgical intervention; (14) Patients with AF and coronary artery disease; (15) Avoiding confusion with NOAC dosing across indications; (16) Cardioversion in a NOAC-treated patient; (17) AF patients presenting with acute stroke while on NOACs; (18) NOACs in special situations; (19) Anticoagulation in AF patients with a malignancy; and (20) Optimizing dose adjustments of VKA. Additional information and downloads of the text and anticoagulation cards in different languages can be found on an EHRA website (www.NOACforAF.eu).

Limitations of Specific Coagulation Tests for Direct Oral Anticoagulants: A Critical Analysis

Background

During treatment with direct oral anticoagulants (DOAC), coagulation assessment is required before thrombolysis, surgery, and if anticoagulation reversal is evaluated. Limited data support the accuracy of DOAC‐specific coagulation assays around the current safe‐for‐treatment threshold of 30 ng/mL.

Methods and Results

In 481 samples obtained from 96 patients enrolled at a single center, DOAC concentrations were measured using Hemoclot direct thrombin inhibitor assay, Biophen direct thrombin inhibitor assay or ecarin clotting time for dabigatran, chromogenic anti‐Xa assay (AXA) for factor Xa inhibitors (rivaroxaban, apixaban) and ultraperformance liquid chromatography–tandem mass spectrometry as reference. All dabigatran‐specific assays had high sensitivity to concentrations >30 ng/mL, but specificity was lower for Hemoclot direct thrombin inhibitor assay (78.2%) than for Biophen direct thrombin inhibitor assay (98.9%) and ecarin clotting time (94.6%). AXA provided high sensitivity and specificity for rivaroxaban, but low sensitivity for apixaban (73.8%; concentrations up to 82 ng/mL were misclassified as <30 ng/mL). If no DOAC‐specific calibration for AXA is available, results 2‐fold above the upper limit of normal indicate relevant rivaroxaban concentrations. For apixaban, all elevated results should raise suspicion of relevant anticoagulation.

Conclusions

DOAC‐specific tests differ considerably in diagnostic performance for concentrations close to the currently accepted safe‐for‐treatment threshold. Compared with Biophen direct thrombin inhibitor assay and ecarin clotting time, limited specificity of Hemoclot direct thrombin inhibitor assay poses a high risk of unnecessary anticoagulation reversal or treatment delays in patients on dabigatran. While AXA accurately detected rivaroxaban, the impact of low apixaban levels on the assay was weak. Hence, AXA results need to be interpreted with extreme caution when used to assess hemostatic function in patients on apixaban.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov. Unique identifiers: NCT02371044, NCT02371070.

Patients on NOACs in the Emergency Room

PURPOSE OF REVIEW

Despite the increasing use of NOACs, there is still uncertainty on how to treat NOAC patients presenting with neurological emergencies. Initial assessment of coagulation status is challenging but essential in these patients to provide best-possible treatment in case of ischemic or hemorrhagic stroke. Meanwhile, anticoagulation reversal strategies have been suggested; yet, the optimal management is still unestablished. The current review aims to provide up-to-date information on (i) how to identify patients with NOAC intake, (ii) which therapies are feasible in the setting of ischemic and hemorrhagic stroke as well as traumatic intracranial hemorrhage, and (iii) how to proceed with patients requiring emergency lumbar puncture.

RECENT FINDINGS

Despite several expert opinions, there is still an ongoing debate which NOAC patients presenting with ischemic stroke may benefit from recanalizing strategies and whether these treatment approaches can be performed safely. Results from two phase IV trials investigating the efficacy of NOAC-specific reversal agents in case of major bleeding seem promising with regard to hemostatic parameters, but these antidotes have not been verified to clinically benefit patients, and approval by authorities in parts is still pending. Specific reversal agents are on the way and will provide new treatment options in patients with NOAC-related ischemic and hemorrhagic stroke. Up to now, the decision which patients should undergo recanalizing treatment for ischemic stroke, or which specific pharmacological reversal treatment in hemorrhagic stroke should be initiated, has to be made cautiously on an individual basis after assessing hemostatic parameters.

Cerebral Ischemia in Patients on Direct Oral Anticoagulants

Background and Purpose—

In patients with ischemic stroke on therapy with vitamin K antagonists, stroke severity and clinical course are affected by the quality of anticoagulation at the time of stroke onset, but clinical data for patients using direct oral anticoagulants (DOACs) are limited.

Methods—

Data from our registry including all patients admitted with acute cerebral ischemia while taking oral anticoagulants for atrial fibrillation between November 2014 and October 2017 were investigated. The activity of vitamin K antagonists was assessed using the international normalized ratio on admission and categorized according to a threshold of 1.7. DOAC plasma levels were measured using the calibrated Xa-activity (apixaban, rivaroxaban, and edoxaban) or the Hemoclot-assay (dabigatran) and categorized into low (<50 ng/mL), intermediate (50–100 ng/mL), or high (>100 ng/mL). Primary objective was the association between anticoagulant activity and clinical and imaging characteristics.

Results—

Four hundred sixty patients were included (49% on vitamin K antagonists and 51% on DOAC). Patients on vitamin K antagonists with low international normalized ratio values had higher scores on the National Institutes of Health Stroke Scale and a higher risk of large vessel occlusion on admission. For patients on DOAC, plasma levels were available in 75.6% and found to be low in 49 (27.7%), intermediate in 41 (23.2%), and high in 87 patients (49.2%). Low plasma levels were associated with higher National Institutes of Health Stroke Scale scores on admission (low: 8 [interquartile range, 3–15] versus intermediate: 4 [1–11] versus high: 3 [0–8]; P <0.001) and higher risk of persisting neurological deficits or cerebral infarction on imaging (85.7% versus 75.6% versus 54.0%; P <0.001). Low DOAC plasma levels were an independent predictor of large vessel occlusion (odds ratio, 3.84 [95% CI, 1.80–8.20]; P =0.001).

Conclusions—

The activity of anticoagulation measured by specific DOAC plasma levels on admission is associated with stroke severity and presence of large vessel occlusion.

Clinical presentation, diagnostic findings and management of cerebral ischemic events in patients on treatment with non-vitamin K antagonist oral anticoagulants - A systematic review

Background

Non-vitamin K antagonist oral anticoagulants (NOAC) are equally or potentially superior in terms of effectiveness in the prevention of ischemic stroke and carry a lower associated risk of intracranial hemorrhage compared to Vitamin K antagonists. Nevertheless, ischemic strokes also occur in patients who are being treated with NOAC. In those particular patients, knowledge about the underlying stroke etiology, clinical presentation, acute management, and complication rates is scarce.

Objective

Systematic literature review to provide a comprehensive clinical overview in terms of presentation, laboratory, imaging parameters and outcomes of patients suffering from acute cerebral ischemic events (i.e. TIA and acute ischemic stroke) while on treatment with a NOAC. Only if available, comparison to VKA is presented which was not the primary focus of this analysis.

Data sources

PubMed/MEDLINE, Scopus and EMBASE from January 1, 2006, to November 20, 2018.

Study eligibility criteria

52 studies providing detailed information on a total of 12247 patients were included. We excluded case reports and case series with less than five patients.

Study appraisal and synthesis method

We systematically assessed study quality using a bias tool and pooled consistent data.

Results

Existing data indicates milder stroke severity and smaller infarct size of acute ischemic stroke on treatment with NOAC compared to stroke occurrence on Vitamin K antagonists (VKA). Established risk factors for ischemic events also play a role in stroke while on NOACs, albeit the underlying etiology remains poorly understood. Intravenous thrombolysis and endovascular therapy seem to be safe and effective, but patient selection for recanalization therapies is challenging.

Limitations

Limited quality of published data, duplicate cases, statistical issues of data pooling, possible incomplete retrieval of identified research and reporting bias might have limited our findings.

Conclusions

Acute ischemic events despite treatment with NOAC therapy are insufficiently investigated.

Systematic review registration number

PROSPERO: CRD42018074853.

Non-vitamin K-dependent oral anticoagulants have a positive impact on ischaemic stroke severity in patients with atrial fibrillation

Aims

Several studies showed reduced stroke severity in patients with atrial fibrillation (AF) if the international normalized ratio (INR) was ≥ 2 at stroke onset. There are no respective data for non-vitamin K-dependent oral anticoagulants (NOACs). The aim of this study was to compare the impact of NOAC or phenprocoumon intake on stroke severity.

Methods and results

In this single-centre observational study, 3669 patients with acute ischaemic stroke were retrospectively analysed regarding AF status and medication immediately before admission. Using multivariable regression, we analysed the association of pre-admission anticoagulation with severe stroke (National Institutes of Health Stroke Scale score ≥ 11) on admission and poor outcome at discharge (modified Rankin scale score > 2). Before the index stroke, 655 patients had known AF and a CHA2DS2-VASc score ≥ 2. While 325 (49.6%) patients were anticoagulated, 159 (24.3%) were prescribed a NOAC and 75 (11.5%) phenprocoumon patients had an INR ≥ 2 on admission. Compared with AF patients without medical stroke prevention, an INR ≥ 2 [OR 0.23 (95% CI 0.10-0.53)] or NOAC intake [OR 0.48 (95% CI 0.27-0.86)] were associated with a lower probability of severe stroke after adjustment for confounders, while an INR < 2 [OR 0.62 (95% CI 0.33-1.16)] was not. Adjusted odds ratios for poor functional outcome at hospital discharge were 0.47 (95% CI 0.27-0.84) for NOAC patients, 0.33 (95% CI 0.17-0.65) for INR ≥ 2 and 0.61 (95% CI 0.32-1.16) for INR < 2.

Conclusion

NOAC intake before stroke did reduce the probability of severe stroke on hospital admission and poor functional outcome at hospital discharge as similarly demonstrated for phenprocoumon patients with an INR ≥ 2 on admission.

Rationale and design of the Registry of Acute Stroke Under Novel Oral Anticoagulants-prime (RASUNOA-prime)

Background

Anticoagulation with vitamin K antagonists and non-vitamin K antagonists oral anticoagulants (NOAC) is effective in stroke prevention in patients with atrial fibrillation. However, anticoagulation also poses a major challenge for emergency treatment of patients suffering ischaemic stroke or intracerebral haemorrhage.

Aim

The registry RASUNOA-prime is designed to describe current patterns of emergency management, clinical course and outcome of patients with atrial fibrillation experiencing an acute ischaemic stroke or intracerebral haemorrhage under different anticoagulation schemes prior to stroke (NOAC, vitamin K antagonists or no anticoagulation).

Methods and design

RASUNOA-prime (ClinicalTrials.gov, NCT02533960) is a prospective, investigator-initiated, multicentre, observational cohort study aiming to recruit 3000 patients with acute ischaemic stroke and atrial fibrillation, and 1000 patients with acute intracerebral haemorrhage and atrial fibrillation with different anticoagulation schemes pre-stroke. It is a non-interventional triple-armed study aiming at a balanced inclusion of ischaemic stroke and intracerebral haemorrhage patients according to the different anticoagulation schemes. Patients will be followed up for clinical course, management and outcome up to three months after the event. Findings in ischaemic stroke and intracerebral haemorrhage patients on NOAC will be compared with patients taking vitamin K antagonists or no anticoagulant pre-stroke.

Study outcomes

Primary endpoint for ischaemic stroke patients: occurrence of symptomatic intracerebral haemorrhage, for intracerebral haemorrhage patients: occurrence of secondary haematoma expansion. Secondary endpoints include assessment of coagulation, use of thrombolysis and/or mechanical thrombectomy, occurrence of complications, implementation of secondary prevention.

Summary

Describing the current patterns of early management as well as outcome of stroke patients with atrial fibrillation will help guide physicians to develop recommendations for emergency treatment of stroke patients under different anticoagulation schemes.

Outcomes of intraparenchymal hemorrhage after direct oral anticoagulant or vitamin K antagonist therapy: A systematic review and meta-analysis

Direct Oral Anticoagulants (DOAC) are increasingly used as an alternative to vitamin-K antagonists (VKA) for anticoagulation and have shown lower rates of intracranial hemorrhage; however, there is disagreement in the literature over the outcomes of the intraparenchymal hemorrhages (IPH) associated with DOACs, and clinical concern regarding the lack of standardized reversal strategies for DOACs. Thus, the aim of this meta-analysis was to compare mortality, hematoma volume, and risk of hematoma expansion in patients who developed an IPH on DOACs versus VKA. A systematic review of the literature was conducted in accordance with the PRISMA guidelines. Studies were selected that reported on mortality, hematoma expansion, and hematoma volume in DOAC-associated IPH. Pooled risk ratios (RR) were calculated for mortality and hematoma expansion and pooled mean difference (MD) was calculated for hematoma volume (ml) using random-effect models. 15 studies reporting on 1238 patients were included in the systematic review. Eleven of these compared DOAC-IPH to VKA-IPH and were pooled quantitatively. DOAC-IPH was not associated with increased mortality risk (RR: 0.95, 95%-CI: 0.72 -1.27) or increased hematoma expansion risk (RR: 0.92; 95%-CI: 0.75-1.12) compared to VKA-IPH. The hematoma volume of DOAC- IPH was statistically significantly smaller than VKA-IPH (MD: -12.14 ml; 95%-CI: -15.38; -8.89). In conclusion, DOAC-IPH was not associated with increased mortality or hematoma expansion compared to VKA-IPH and may be associated with a smaller hematoma volume.

Management of patients with stroke treated with direct oral anticoagulants

Since their market approval, direct oral anticoagulants (DOACs) are being increasingly used for stroke prevention in patients with atrial fibrillation. However, the management of DOAC-treated patients with stroke poses several challenges for physicians in everyday clinical practice, both in the acute setting and in long-term care. This has spurred extensive research activity in the field over the past few years, which we review here.

Coagulation Testing in Intracerebral Hemorrhage Related to Non-vitamin K Antagonist Oral Anticoagulants

BACKGROUND

Intracerebral hemorrhage (ICH) is a life-threatening complication of non-vitamin K antagonist oral anticoagulants (NOAC). Little is known about the effect of intensity of anticoagulation on NOAC-ICH. We describe the current use of coagulation testing in the emergency setting and explore associations with baseline size and expansion of hematoma as determined in a previous study.

METHODS

Data from the prospective multicenter RASUNOA registry were analyzed. Patients with NOAC-ICH were enrolled between February 2012 and December 2014. Frequency of local test performance of specific (anti-factor Xa tests, diluted thrombin time) and non-specific tests (international normalized ratio (INR), activated partial thromboplastin time (aPTT), thrombin time) was analyzed. The association of anticoagulation intensity at admission with hematoma volume and hematoma expansion was explored.

RESULTS

In 61 NOAC-ICH patients enrolled at 21 centers, drug-specific coagulation testing was performed in 16 cases (26%), and only 29% of centers appeared to use drug-specific tests in NOAC-ICH at all. In some cases, INR and aPTT values were normal despite drug concentrations in the peak range. In patients with available drug-specific concentrations, 50% had drug levels in the peak range at admission. Higher intensity of anticoagulation was not associated with higher hematoma volume at admission or with subsequent hematoma expansion.

CONCLUSION

Drug-specific tests are only infrequently used in NOAC-ICH. Normal results in non-specific coagulation do not reliably rule out peak range concentrations. Anticoagulation intensity at admission does not predict baseline hematoma volume or subsequent hematoma expansion.

Safety of Recanalization Therapy in Patients with Acute Ischemic Stroke Under Anticoagulation: A Systematic Review and Meta-Analysis

BACKGROUND

Intravenous thrombolysis treatment (IVT) and endovascular therapy (EVT) have been proved as fist-line beneficial option for eligible patients who have acute ischemic stroke (AIS) with major safety concern of symptomatic intracranial hemorrhage (sICH). Unfortunately, the emergency management of patients with AIS taking vitamin K antagonists and with international normalized ratio higher than 1.7 or taking new oral anticoagulants (NOACs) represents a great challenge. We aim to comprehensively determine the safety of EVT in patients under prior-stroke anticoagulants and IVT in patients under NOAC use.

METHODS

Clinical researches published in the Embase, PubMed, and Cochrane Library electronic databases up to December 2017 were identified for analysis. Subgroup and sensitivity analyses were also conducted to evaluate the robustness of the conclusions.

RESULTS

Overall, 9 studies involving 3885 patients met the inclusion criteria. The rate of sICH (risk ratio [RR] = .94, 95% CI = .61-1.47, P = .799), mortality (P = .495), and recanalization (P = .655) after EVT did not differ between patients under and those who were not under anticoagulants, although patients under anticoagulants were less likely to achieve good functional outcome (P < .001) than those who were not. Moreover, prior NOAC therapy was not significantly associated with increasing sICH in patients with AIS after IVT (RR = .79, 95% CI = .41-1.53, P = .492).

CONCLUSIONS

Patients under anticoagulation appear to be safe after EVT with relatively lower rate of good outcome; furthermore, prior NOAC therapy was not associated with an increasing sICH rate after IVT. This offered a practical information to select appropriate therapeutic strategies for patients under anticoagulation, although the level of evidence seems to be quite shaky.

Intravenous Thrombolysis in Patients with Stroke Taking Rivaroxaban Using Drug Specific Plasma Levels: Experience with a Standard Operation Procedure in Clinical Practice

Background and Purpose

Standard operating procedures (SOP) incorporating plasma levels of rivaroxaban might be helpful in selecting patients with acute ischemic stroke taking rivaroxaban suitable for IVthrombolysis (IVT) or endovascular treatment (EVT).

Methods

This was a single-center explorative analysis using data from the Novel-Oral-Anticoagulants-in-Stroke-Patients-registry (clinicaltrials.gov:NCT02353585) including acute stroke patients taking rivaroxaban (September 2012 to November 2016). The SOP included recommendation, consideration, and avoidance of IVT if rivaroxaban plasma levels were <20 ng/mL, 20‒100 ng/mL, and >100 ng/mL, respectively, measured with a calibrated anti-factor Xa assay. Patients with intracranial artery occlusion were recommended IVT+EVT or EVT alone if plasma levels were ≤100 ng/mL or >100 ng/mL, respectively. We evaluated the frequency of IVT/EVT, door-to-needle-time (DNT), and symptomatic intracranial or major extracranial hemorrhage.

Results

Among 114 acute stroke patients taking rivaroxaban, 68 were otherwise eligible for IVT/EVT of whom 63 had plasma levels measured (median age 81 years, median baseline National Institutes of Health Stroke Scale 6). Median rivaroxaban plasma level was 96 ng/mL (inter quartile range [IQR] 18‒259 ng/mL) and time since last intake 11 hours (IQR 4.5‒18.5 hours). Twenty-two patients (35%) received IVT/EVT (IVT n=15, IVT+EVT n=3, EVT n=4) based on SOP. Median DNT was 37 (IQR 30‒60) minutes. None of the 31 patients with plasma levels >100 ng/mL received IVT. Among 14 patients with plasma levels ≤100 ng/mL, the main reason to withhold IVT was minor stroke (n=10). No symptomatic intracranial or major extracranial bleeding occurred after treatment.

Conclusions

Determination of rivaroxaban plasma levels enabled IVT or EVT in one-third of patients taking rivaroxaban who would otherwise be ineligible for acute treatment. The absence of major bleeding in our pilot series justifies future studies of this approach.