Rivaroxaban plasma levels in acute ischemic stroke and intracerebral hemorrhage

Direct oral anticoagulants in trauma patients

PURPOSE OF REVIEW

Direct oral anticoagulants (DOACs) are increasingly prescribed for prevention of thromboembolic events. Thus, trauma care providers are facing a steadily raising number of injured patients on DOACs.

RECENT FINDINGS

Despite a predictable pharmacokinetic profile, the resulting plasma levels of trauma patients upon admission and bleeding risks remain uncertain. Therefore, recent guidelines recommend the measurement of DOAC plasma concentrations in injured patients. Alternatively, DOAC specific visco-elastic tests assays can be applied to identify DOAC patients at bleeding risk.Bleeding complications in trauma patients on DOACs are generally higher compared to nonanticoagulated subjects, but comparable to vitamin K antagonists (VKAs). In particular, a traumatic brain injury does not carry an increased risk of intracranial bleeding due to a DOAK intake compared to VKAs. Current studies demonstrated that up to 14% of patients with a hip fracture are on DOACs prior to surgery. However, the majority can be operated safely within a 24h time window without an increased bleeding rate.Specific antagonists facilitate rapid reversal of patients on DOACs. Idarucizumab for dabigatran, and andexanet alfa for apixaban and rivaroxaban have been approved for life threatening bleeding. Alternatively, prothrombin complex concentrate can be used. Dialysis is a potential treatment option for dabigatran and haemoabsorption with special filters can be applied in patients on FXa-inhibitors.

SUMMARY

Current guidelines recommend the measurement of DOAC plasma levels in trauma patients. Compared to VKAs, DOACs do not carry a higher bleeding risk. DOAC specific antagonists facilitate the individual bleeding management.

Urine-based point-of-care testing for factor-Xa-inhibitors in acute ischemic stroke patients: a feasibility study

Introduction

Direct oral anticoagulants (DOACs) have become widely used in clinical practice for preventing thromboembolic events. Point-of-care testing methods, particularly those based on urine samples, offer a promising approach for rapid and accurate assessment of DOAC presence. This pilot study aims to evaluate the utility of a urine-based DOAC dipstick test as a point-of-care tool for identifying DOAB presence in acute ischemic stroke (AIS) or transient ischemic attack (TIA) patients.

Patients and methods

This prospective pilot study included patients with AIS/TIA eligible for DOAC-measurement. After exclusion of 3 patients, 23 patients with DOAC-intake (DOAC group; factor-Xa-inhibitors; n = 23) and 21 patients without DOAC-intake (control-group) remained for analyses. The urine-based DOAC dipstick test and parallel blood-based specific DOAC-level assessment were performed in all patients. Time-intervals of sampling urine/blood sampling and result of DOAC-test were recorded to analyze a potential time benefit based on dipstick evaluation.

Results

The urine-based DOAC dipstick test demonstrated high sensitivity (100%) and specificity (100%), correctly identifying all patients with anticoagulatory activity due to DOAC intake (i.e., anti-Xalevel ≥30 ng/mL). Moreover, the visual readout of the test provided semiquantitative information on drug-specific anti-Xa levels, showing a sensitivity of 83% and specificity of 93% to detect anti-Xa levels ≥120 ng/mL. The dipstick test exhibited a median time-benefit of 2:25 h compared to standard blood-based DOAC-level testing.

Discussion

The results of this pilot study underline the efficacy of urine-based point-of-care testing as a rapid and reliable method for assessing DOAC presence in patients with acute ischemic stroke.

Conclusion

The value of this tool for clinical decision-making in stroke management needs to be established in future trials.Clinical Trial Registration: Clinicaltrails.org identifier [NCT06037200].

DOAC plasma concentration upon hospital admission in a cohort of trauma patients. An observational real-life study

PURPOSE

Due to a better safety profile, direct oral anticoagulants (DOACs) are increasingly prescribed for prevention of thromboembolic events. However, little is known about DOAC plasma concentrations in trauma patients upon hospital admission. Thus, we investigated the frequency and extent of DOAC possible over- and underdosing in trauma patients upon hospital admission.

METHODS

In this single-center retrospective study, DOAC plasma concentrations of adult trauma patients were analyzed with specific calibrated anti-IIa (dabigatran) and anti-Xa (apixaban, edoxaban and rivaroxaban) tests within 4 h after hospital admission.

RESULTS

A total of 210 trauma patients, admitted between 2019 and 2022, were included in the analyses. Low DOAC levels < 30 ng/mL were detected in 13.3% of the patients. In 7.1% of the patients, DOAC plasma levels ranged between 300-399 ng/mL and further 7.1% exhibited plasma concentrations > 400 ng/mL. The highest incidence of high to very high DOAC plasma concentration was observed for patients on rivaroxaban and dabigatran. A moderate correlation was observed between dabigatran plasma concentration and estimated glomerular filtration rate (rho = - 0.5338, p = 0.0003). For rivaroxaban no clear association between plasma concentration and liver or renal function could be detected. Patients on statins had significantly higher DOAC concentration in comparison with those not taking statins (153 (76-274) vs 108 (51-217) ng/mL, p = 0.046).

CONCLUSION

The current study revealed that patients on dabigatran and rivaroxaban were prone to higher DOAC plasma levels upon hospital admission in comparison with apixaban and edoxaban. DOAC plasma level measurement in trauma patients might be warranted due to unpredictively low or high plasma concentrations. However, the clinical impact of altered plasma levels on both, bleeding and thromboembolic events, remains to be determined by future studies.

Pharmacokinetic and Pharmacogenetic Predictors of Major Bleeding Events in Patients with an Acute Coronary Syndrome and Atrial Fibrillation Receiving Combined Antithrombotic Therapy

Objective: This study's objective was to evaluate the effects of pharmacokinetic and pharmacogenetic factors on major bleeding in patients with ACS and non-valvular AF receiving combined antithrombotic therapy consisting of rivaroxaban, clopidogrel, and aspirin as part of dual or triple therapy. Methods: A prospective observational study was conducted in two PCI centers in Moscow, the Russian Federation, from 2017 to 2018. One hundred patients with ACS and AF were enrolled. Prospective follow-ups continued for 12 months. Results: A total of 36 patients experienced bleeding events, with 10 experiencing major bleeding based on the BARC scale and 17 experiencing major bleeding based on the ISTH scale. The following predictors associated with an increased number of major bleeding events were identified: for the ISTH scale, a Css min. of rivaroxaban of >137 pg/mL (5.94 OR, (95% CI, 3.13-12.99; p < 0.004)) and carriage of the T allelic variant polymorphism ABCB1 rs4148738 (8.97 OR (95% CI, 1.48-14.49; p < 0.017)), as well as for the BARC scale (5.76 OR (95% CI, 2.36-9.87; p < 0.018)). Conclusions: Measuring residual steady-state rivaroxaban concentrations and determining the carriage of the T allelic variant polymorphism ABCB1 rs4148738 may be applicable to high-risk patients for subsequent antithrombotic therapy modification.

Atrial Fibrillation and Ischemic Stroke despite Oral Anticoagulation

Patients with atrial fibrillation (AF) experiencing ischemic stroke despite oral anticoagulation (OAC), i.e., breakthrough strokes, are not uncommon, and represent an important clinical subgroup in view of the consistently high risk of stroke recurrence and mortality. The understanding of the heterogenous potential mechanism underlying OAC failure is essential in order to implement specific therapeutic measures aimed at reducing the risk of recurrent ischemic stroke. However, due to the incomplete comprehension of this phenomenon and the limited available data, secondary stroke prevention in such high-risk patients represents a clinical dilemma. There are several available strategies to prevent ischemic stroke recurrence in AF patients with breakthrough stroke in the absence of competing causes unrelated to AF, and these include continuation or change in the type of OAC, addition of antiplatelet therapy, left atrial appendage closure, or any combination of the above options. However, due to the limited available data, the latest guidelines do not provide any specific recommendations about which of the above strategies may be preferred. This review describes the incidence, the clinical impact and the potential mechanisms underlying OAC failure in AF patients. Furthermore, the evidence supporting each of the above therapeutic options for secondary stroke prevention and the potential future directions will be discussed.

Role of DOAC plasma concentration on perioperative blood loss and transfusion requirements in patients with hip fractures

BACKGROUND

There is an ever-increasing number of hip fracture (HF) patients on direct oral anticoagulants (DOAC). The impact of DOAC plasma level prior to HF surgery on perioperative blood loss and transfusion requirements has not been investigated so far.

MATERIALS AND METHODS

In this retrospective study of HF patients on DOACs admitted to the AUVA Trauma Center Salzburg between February 2015 and December 2021. DOAC plasma levels were analysed prior to surgery. Patients were categorized into four DOAC groups: Group A < 30 ng/mL, Group B 30-49 ng/mL, Group C 50-79 ng/mL, and Group D ≥ 80 ng/mL. Haemoglobin concentration was measured upon admission, prior to surgery, after ICU/IMC admission, and on day 1 and 2 post-surgery. Difference in the blood loss via drains, transfusion requirements and time to surgery were compared.

RESULTS

A total of 155 subjects fulfilled the predefined inclusion criteria. The median age of the predominantly female patients was 86 (80-90) years. Haemoglobin concentration in Group D was lower upon admissions but did not reach statistical significance. The decrease in haemoglobin concentration over the entire observation time was comparable between groups. Blood transfusion requirements were significantly higher in Group D compared to Group A and B (p = 0.0043). Time to surgery, intra- and postoperative blood loss via drains were not different among groups.

CONCLUSION

No strong association between the DOAC plasma levels and perioperative blood loss was detected. Higher transfusion rates in patients with DOAC levels ≥ 80 ng/mL were primarily related to lower admission haemoglobin levels. DOAC concentration measurement is feasible and expedites time to surgery.

Intravenous Thrombolysis With Alteplase at 0.6 mg/kg in Patients With Ischemic Stroke Taking Direct Oral Anticoagulants

Background

We elucidated the safety of treatment with alteplase at 0.6 mg/kg within 24 hours for patients on direct oral anticoagulants (DOACs) before ischemic stroke onset.

Methods and Results

Consecutive patients with acute ischemic stroke who underwent intravenous thrombolysis using alteplase at 0.6 mg/kg from 2011 to 2021 were enrolled from our single‐center prospective stroke registry. We compared outcomes between patients taking DOACs and those not taking oral anticoagulants within 48 hours of stroke onset. The primary safety outcome was the rate of symptomatic intracranial hemorrhage with a ≥4‐point increase on the National Institutes of Health Stroke Scale score from baseline. The efficacy outcome was defined as 3‐month modified Rankin Scale score of 0 to 2 after stroke onset. Of 915 patients with acute ischemic stroke who received intravenous thrombolysis (358 women; median age, 76 years; median National Institutes of Health Stroke Scale score, 10), 40 patients took DOACs (6 took dabigatran, 8 took rivaroxaban, 16 took apixaban, and 10 took edoxaban) within 24 hours of onset and 753 patients did not take any oral anticoagulants. The rate of symptomatic intracranial hemorrhage was comparable between patients on DOACs and those not on oral anticoagulants (2.5% versus 2.4%, P=0.95). The rate of favorable outcomes was comparable between the 2 groups (59.4% versus 58.2%, P=0.46), although the admission National Institutes of Health Stroke Scale score was higher in patients on DOACs. No significant differences showed in any intracranial hemorrhage within 36 hours or mortality at 3 months.

Conclusions

Intravenous thrombolysis would be safely performed for patients on DOACs following the recommendations of the Japanese guidelines.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02251665.

Safety and efficacy of endovascular thrombectomy in acute ischemic stroke treated with anticoagulants: a systematic review and meta-analysis

Background

Endovascular thrombectomy (EVT) is an effective therapy in acute ischemic stroke (AIS) with large vessel occlusion, especially for those who are unsuitable for intravenous thrombolysis. However, the safety and efficacy of EVT in AIS patients who receiving oral anticoagulants (OACs) is unclear, especially for the risk of symptomatic intracranial hemorrhage (sICH). 

Methods

Database of PubMed, Embase, and Cochrane Library were searched from Jan 1, 2000, through the final search date of Jun 2, 2021. Eligible studies for enrollment required outcomes reported for events of sICH, mortality, functional status, and successful reperfusion. Meta-analysis was conducted to compare the outcomes difference after EVT between AIS patients with or without OACs use. The primary safety outcome was sICH after EVT, and the primary efficacy outcome was functional status at 3 months. 

Results

One thousand nine hundred forty studies were screened for eligibility and 15 of them were included in the meta-analysis. Compared the OACs group to control arm, vitamin K antagonists (VKAs) was associated with higher risk of sICH (OR 1.49, 95% CI 1.10–2.02) and mortality (OR 1.67, 95% CI 1.35–2.06). Poor functional outcomes were noted both in the VKAs and direct oral anticoagulants (DOACs) groups (OR 0.62, 95% CI 0.54–0.71 and OR 0.61, 95% CI 0.53–0.71, respectively). No differences in successful reperfusion were observed.

Conclusions

Comparing with DOACs, VKAs use was associated with a higher risk of sICH and mortality after EVT. Patients who did not receive OACs exhibited more favorable outcomes. The successful reperfusion did not differ between groups. However, results for mortality and functional outcomes have to be interpreted with caution since they are based on non-randomized data and unadjusted proportions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-022-00394-y.

Aetiology, secondary prevention strategies and outcomes of ischaemic stroke despite oral anticoagulant therapy in patients with atrial fibrillation

OBJECTIVE

To investigate the aetiology, subsequent preventive strategies and outcomes of stroke despite anticoagulation in patients with atrial fibrillation (AF).

METHODS

We analysed consecutive patients with AF with an index imaging-proven ischaemic stroke despite vitamin K-antagonist (VKA) or direct oral anticoagulant (DOAC) treatment across 11 stroke centres. We classified stroke aetiology as: (i) competing stroke mechanism other than AF-related cardioembolism; (ii) insufficient anticoagulation (non-adherence or low anticoagulant activity measured with drug-specific assays); or, (iii) AF-related cardioembolism despite sufficient anticoagulation. We investigated subsequent preventive strategies with regard to the primary (composite of recurrent ischaemic stroke, intracranial haemorrhage, death) and secondary endpoint (recurrent ischaemic stroke) within 3 months after index stroke.

RESULTS

Among 2946 patients (median age 81 years; 48% women; 43% VKA, 57% DOAC), stroke aetiology was competing mechanism in 713 patients (24%), insufficient anticoagulation in 934 (32%) and cardioembolism despite sufficient anticoagulation in 1299 (44%). We found high rates of the primary (27% of patients; completeness 91.6%) and secondary endpoint (4.6%; completeness 88.5%). Only DOAC (vs VKA) treatment after index stroke showed lower odds for both endpoints (primary: adjusted OR (aOR) (95% CI) 0.49 (0.32 to 0.73); secondary: 0.44 (0.24 to 0.80)), but not switching between different DOAC types. Adding antiplatelets showed higher odds for both endpoints (primary: aOR (95% CI) 1.99 (1.25 to 3.15); secondary: 2.66 (1.40 to 5.04)). Only few patients (1%) received left atrial appendage occlusion as additional preventive strategy.

CONCLUSIONS

Stroke despite anticoagulation comprises heterogeneous aetiologies and cardioembolism despite sufficient anticoagulation is most common. While DOAC were associated with better outcomes than VKA, adding antiplatelets was linked to worse outcomes in these high-risk patients. Our findings indicate that individualised and novel preventive strategies beyond the currently available anticoagulants are needed.

TRIAL REGISTRATION NUMBER

ISRCTN48292829.

Plasma Rivaroxaban Level in Patients With Early Stages of Chronic Kidney Disease-Relationships With Renal Function and Clinical Events

Introduction Drug accumulation of rivaroxaban is a concern in patients with chronic kidney disease (CKD). Data regarding the plasma rivaroxaban levels in early CKD patients and its relationship with clinical events is lacking. Methods Early CKD patients (Stage 1-3) with atrial fibrillation who received rivaroxaban (15 or 20 mg daily) were recruited. Plasma rivaroxaban levels were measured at 2 hours (peak) and 24 hours (trough) after drug administration, and correlated with eGFR and clinically significant events during the follow-up period (1 January 2018 to 31 October 2021). Results Ninety-two patients were included (CKD stage 1 n=10, stage 2 n=53, stage 3 n=29). Plasma trough levels in patients with stage 3 CKD were significantly higher than those with stage 2 and 1 CKD (66.0±34.9 ng/ml vs. 35.7 ± 24.7 ng/ml vs. 34.7 ± 26.2 ng/ml, respectively, p=0.005), and showed inverse relationship with eGFR (r=0.391, p=0.001) in patients receiving 20 mg daily. The plasma trough rivaroxaban level correlated with PT and APTT (r = 0.650 and 0.44, respectively, p<0.001 for both). Plasma trough rivaroxaban level in those with bleeding were higher than those who did not (59.9 ± 35.6 ng/ml vs. 41.1 ± 29.2 ng/ml, p=0.011), and multivariate analysis suggested that plasma trough rivaroxaban level was associated with the rate of bleeding complications (OR: 1.020, 95% CI 1.002-1.038, p=0.028). Conclusion Plasma trough rivaroxaban levels correlated with renal function in early CKD patients, and its measurement may help dosage optimization in patients with renal impairment. Moreover, our data suggests that there may be an association between plasma trough rivaroxaban level and the rate of bleeding complication.

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.

Measurement of Anticoagulation in Patients on Dabigatran, Rivaroxaban, and Apixaban Therapy by Novel Automated Thrombelastography

Background  Direct-acting oral anticoagulants (DOACs) do not require monitoring. Measurement of DOAC effect would be useful in the event of bleeding, trauma, and thromboembolism while on anticoagulation. We evaluated the effectiveness of the investigational DOAC assays on the TEG®6s Hemostasis Analyzer to assess the anticoagulant effect of DOACs in patients treated for atrial fibrillation or deep vein thrombosis (DVT). Methods  Patients on treatment for a minimum of 7 days with standard doses of dabigatran, rivaroxaban, and apixaban were included. DOAC plasma concentrations and TEG®6s Reaction (R)-time were measured and correlated. The sensitivity, specificity, and negative predictive value (NPV) of R-time to detect DOAC concentrations of ≥30, ≥50, and ≥100 ng/mL were calculated. Results  A total of 189 patients were included, ( n  = 50) on apixaban, ( n  = 62) on rivaroxaban, ( n  = 53) on dabigatran, and ( n  = 24) on no DOAC were studied. Using the direct thrombin inhibitor (DTI) channel, R-time demonstrated strong linear correlation with dabigatran levels (r = 0.93, p  < 0.0001). Using the antifactor Xa (AFXa) channel, R-time demonstrated strong nonlinear correlation with rivaroxaban and apixaban levels ( r _s  = 0.92 and 0.84, respectively, p  < 0.0001 for both). R-time revealed strong sensitivity and NPV in detecting low DOAC levels for the predefined concentrations. Conclusion  R-time measured by TEG®6s DOAC-specific cartridge has a strong correlation with concentrations of the most commonly used DOACs with high sensitivity and NPV for detecting lower drug levels that are considered clinically relevant for patients in need of antidote, or prior to urgent surgery. Further studies to determine the relation of R-time to clinical outcomes are warranted.

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.

Ischaemic stroke in anticoagulated patients with atrial fibrillation

Anticoagulation substantially reduces the risk of stroke in patients with atrial fibrillation (AF). However, recent studies have shown that up to 22%-36% of patients on anticoagulation will suffer an ischaemic stroke (IS). In this narrative review, we provide an overview of risk factors, mechanisms, management of acute IS and strategies for secondary prevention for patients with AF with stroke despite oral anticoagulation. For this paper, we reviewed available literature from important studies (randomised clinical trials, meta-analyses, reviews and case series) on patients with IS despite anticoagulation. We focused on recent studies that examined safety and efficacy of acute stroke treatments and evaluation and management strategies for secondary prevention. The literature review suggests that patients with AF with IS despite anticoagulation are a heterogeneous group with several possible mechanisms, which may include reduced or non-adherence to anticoagulation, competing non-cardioembolic stroke aetiologies or cardioembolic mechanisms separate from AF. The identification of one or more possible mechanisms of stroke despite anticoagulation may allow for a more targeted and individualised approach for secondary prevention. There are limited data to guide management in such patients, and strategies to prevent recurrent strokes include strict risk factor control and therapies targeting the most likely stroke mechanism. In cases where AF is suspected to be the culprit, clinical trials are needed to test the safety and efficacy of left atrial appendage occlusion plus anticoagulation versus continued anticoagulation alone.

Pharmacokinetics of Direct Oral Anticoagulants in Emergency Situations: Results of the Prospective Observational RADOA-Registry

BACKGROUND

Direct oral anticoagulants (DOACs) are increasingly used worldwide. Little is known so far about their pharmacokinetics in emergency situations.

METHODS

A prospective, observational registry was performed to determine the clinical course in consecutive patients with major bleeding or urgent surgery treated with DOACs. In samples collected as part of routine care DOAC drug concentrations were measured using ultraperformance liquid chromatography-tandem mass spectrometry. Anticoagulant intensity at first presentation and drug half-life (t _1/2), tested in repeat samples, were evaluated.

RESULTS

A total of 140 patients were prospectively included. Pharmacokinetic data were available in 94% (132/140) of patients. Note that 67% (89/132) experienced life-threatening bleeding and 33% (43/132) needed an urgent surgery. For pharmacokinetic analysis a total of 605 blood samples was available. Median concentration on admission was 205 ng/mL for rivaroxaban and 108 ng/mL for apixaban. All treatment groups showed a high variation of drug concentrations at baseline. In rivaroxaban-treated patients t _½ was 17.3 hours (95% confidence interval [CI]: 15.4-19.7) without significant difference in both groups (major bleeding: t _½ 16.7 hours, 95% CI: 14.7-19.3; urgent surgery: t _½ 19.7 hours, 95% CI: 15.2-27.9; p = 0.292). In apixaban-treated patients t _½ was 25.0 hours (95% CI: 22.9-27.6) with a longer t _½ after urgent surgery (t _1/2: 30.8 hours; 95% CI: 26.9-36.4) compared with severe bleeding (t _1/2: 20.8 hours; 95% CI: 18.8-23.2; p < 0.001).

CONCLUSION

Emergency patients under DOAC treatment show a high variation of anticoagulant concentrations at baseline. Compared with rivaroxaban, apixaban showed a lower median concentration on admission and a longer t _½.

Plasma levels do not predict thrombin generation in patients taking direct oral anticoagulants

BACKGROUND

The antithrombotic effect of direct oral anticoagulants (DOAC) in specific clinical scenarios is difficult to assess.

OBJECTIVE

This study aimed to evaluate the effect of DOAC on thrombin generation (TG) in relation to their plasma level.

METHODS

Eighty patients newly started on anticoagulation were included, 20 patients for each DOAC-apixaban, edoxaban, rivaroxaban, and dabigatran. Plasma was sampled before DOAC (baseline), at plasma peak time, 6 and 12 hours after starting DOAC for quantification of drug levels and TG.

RESULTS

The baseline TG before DOAC intake showed inter-individual variability. All DOACs significantly prolonged lag time (LT) and time to peak (TTP), but did not change endogenous thrombin potential (ETP). Anti-Xa inhibitors but not dabigatran reduced thrombin peak, but the effect of apixaban at plasma peak was less pronounced (factor 1.6). LT and TTP prolongation of dabigatran was lower compared to anti-Xa inhibitors. All DOACs showed a nonlinear dose-response relationship, with the greatest antithrombotic effect at lower DOAC plasma levels. The inhibition of TG parameters between baseline and peak was parallel between individual patients but the coefficient of variation of TG was lower compared to drug levels.

CONCLUSION

The antithrombotic effect at DOAC peak plasma level measured by TG depends on the patient-specific baseline TG level and the drug-specific inhibition by the particular DOAC. Although peak plasma levels have a high variability, the variation of TG is lower compared to drug levels. Therefore, TG assays may be superior to plasma levels in the assessment of the intensity of anticoagulation.

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.

Small vessel disease burden and intracerebral haemorrhage in patients taking oral anticoagulants

OBJECTIVE

We investigated the contribution of small vessel disease (SVD) to anticoagulant-associated intracerebral haemorrhage (ICH).

METHODS

Clinical Relevance of Microbleeds in Stroke-2 comprised two independent multicentre observation studies: first, a cross-sectional study of patients with ICH; and second, a prospective study of patients taking anticoagulants for atrial fibrillation (AF) after cerebral ischaemia. In patients with ICH, we compared SVD markers on CT and MRI according to prior anticoagulant therapy. In patients with AF and cerebral ischaemia treated with anticoagulants, we compared the rates of ICH and ischaemic stroke according to SVD burden score during 2 years follow-up.

RESULTS

We included 1030 patients with ICH (421 on anticoagulants), and 1447 patients with AF and cerebral ischaemia. Medium-to-high severity SVD was more prevalent in patients with anticoagulant-associated ICH (CT 56.1%, MRI 78.7%) than in those without prior anticoagulant therapy (CT 43.5%, p<0.001; MRI 64.5%, p=0.072). Leukoaraiosis and atrophy were more frequent and severe in ICH associated with prior anticoagulation. In the cerebral ischaemia cohort (779 with SVD), during 3366 patient-years of follow-up the rate of ICH was 0.56%/year (IQR 0.27-1.03) in patients with SVD, and 0.06%/year (IQR 0.00-0.35) in those without (p=0.001); ICH was independently associated with severity of SVD (HR 5.0, 95% CI 1.9 to 12.2,p=0.001), and was predicted by models including SVD (c-index 0.75, 95% CI 0.63 to 0.85).

CONCLUSIONS

Medium-to-high severity SVD is associated with ICH occurring on anticoagulants, and independently predicts ICH in patients with AF taking anticoagulants; its absence identifies patients at low risk of ICH. Findings from these two complementary studies suggest that SVD is a contributory factor in ICH in patients taking anticoagulants and suggest that anticoagulation alone should no longer be regarded as a sufficient 'cause' of ICH.

TRIAL REGISTRATION

NCT02513316.

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.

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.

A prospective observational study of the rapid detection of clinically-relevant plasma direct oral anticoagulant levels following acute traumatic injury

In urgent clinical situations, such as trauma, urgent surgery or before thrombolysis, rapid quantification of direct oral anticoagulant plasma drug levels is warranted. Using the ClotPro® analyser, we assessed two novel viscoelastic tests for detection of clinically-relevant plasma drug levels in trauma patients. The ecarin clotting time was used to assess the plasma concentration of dabigatran and Russell´s viper venom clotting time to determine the plasma concentration of direct factor Xa inhibitors. In parallel, plasma concentrations were analysed using plasma-based chromogenic assays. A total of 203 simultaneous measurements were performed. Strong to very strong linear correlations were detected between ecarin clotting time and plasma concentration of dabigatran (r = 0.9693), and between Russell´s viper venom clotting time and plasma concentrations of apixaban (r = 0.7391), edoxaban (r = 0.9251) and rivaroxaban (r = 0.8792), all p < 0.001. An ecarin clotting time ≥ 189 seconds provided 100% sensitivity and 90% specificity for detecting plasma dabigatran concentrations ≥ 50 ng.ml^-1 . Corresponding Russell´s viper venom clotting time cut-off values were ≥ 136 seconds for apixaban (80% sensitivity, 88% specificity), ≥ 168 seconds for edoxaban (100% sensitivity, 100% specificity) and ≥ 177 seconds for rivaroxaban (90% sensitivity, 100% specificity). Detection of drug levels ≥ 100 ng.ml^-1 was also investigated: for dabigatran, an ecarin clotting time ≥ 315 seconds yielded 92% sensitivity and 100% specificity; while Russell´s viper venom clotting time cut-offs of 191, 188 and 196 seconds were calculated for apixaban (67% sensitivity, 88% specificity), edoxaban (100% sensitivity, 75% specificity) and rivaroxaban (100% sensitivity, 91% specificity), respectively. We have demonstrated strong positive correlations between plasma drug levels and clotting time values in the specific ClotPro assays. Cut-off values for detecting clinically-relevant drug levels showed high levels of sensitivity and specificity.

Antithrombotic Therapy in Patients with Recent Stroke and Atrial Fibrillation

:

Atrial fibrillation (AF) is a common arrhythmia which carries a significant risk of stroke. Secondary prevention, particularly in the acute phase of stroke with anti-thrombotic therapy, has not been validated. The aim of this review is to evaluate the available evidence on the use of antithrombotic therapy in patients with recent stroke who have AF, and suggest a treatment algorithm for the various time points, taking into account both the bleeding and thrombosis risks posed at each stage.

MRI characteristics in acute ischemic stroke patients with preceding direct oral anticoagulant therapy as compared to vitamin K antagonists

Background

Despite the utility of neuroimaging in the diagnostic and therapeutic management of patients with acute ischemic stroke (AIS), imaging characteristics in patients with preceding direct oral anticoagulants (DOAC) compared to vitamin K antagonists (VKA) have hardly been described. We aimed to determine presence of large vessel occlusion (LVO), thrombus length, infarction diameter, and occurrence of hemorrhagic transformation in AIS patients with preceding DOAC as compared to VKA therapy.

Methods

Using a prospectively collected cohort of AIS patients, we performed univariate and multivariable regression analyses regarding imaging outcomes. Additionally, we provide a sensitivity analysis for the subgroup of patients with confirmed therapeutic anticoagulation.

Results

We included AIS in patients with preceding DOAC (N = 75) and VKA (N = 61) therapy, median age 79 (IQR 70–83), 39% female. Presence of any LVO between DOAC and VKA patients (29.3% versus 37.7%, P = 0.361), and target LVO for endovascular therapy (26.7% versus 27.9%, P = 1.0) was equal with a similar occlusion pattern. DOAC as compared to VKA were associated with a similar rate of target LVO for EVT (aOR 0.835, 95% CI 0.368–1.898). The presence of multiple lesions and characteristics of the thrombus were similar in DOAC and VKA patients. Acute ischemic lesion diameter in real world patients was equal in patients taking DOAC as compared to VKA. Lesion diameter in VKA patients (median 13 mm, IQR 6–26 versus median 20 mm, IQR 7–36, P = 0.001), but not DOAC patients was smaller in the setting of confirmed therapeutic VKA. The frequency of radiological hemorrhagic transformation and symptomatic intracranial hemorrhage in OAC patients was low. Sensitivity analysis considering only patients with confirmed therapeutic anticoagulation did not change any of the results.

Conclusion

Preceding DOAC treatment showed equal rates of LVO and infarct size as compared to VKA in AIS patients. This study adds to the knowledge of imaging findings in AIS patients with preceding anticoagulation.

Endovascular Stroke Treatment and Risk of Intracranial Hemorrhage in Anticoagulated Patients

Background and Purpose- We aimed to determine the safety and mortality after mechanical thrombectomy in patients taking vitamin K antagonists (VKAs) or direct oral anticoagulants (DOACs). Methods- In a multicenter observational cohort study, we used multiple logistic regression analysis to evaluate associations of symptomatic intracranial hemorrhage (sICH) with VKA or DOAC prescription before thrombectomy as compared with no anticoagulation. The primary outcomes were the rate of sICH and all-cause mortality at 90 days, incorporating sensitivity analysis regarding confirmed therapeutic anticoagulation. Additionally, we performed a systematic review and meta-analysis of literature on this topic. Results- Altogether, 1932 patients were included (VKA, n=222; DOAC, n=98; no anticoagulation, n=1612); median age, 74 years (interquartile range, 62-82); 49.6% women. VKA prescription was associated with increased odds for sICH and mortality (adjusted odds ratio [aOR], 2.55 [95% CI, 1.35-4.84] and 1.64 [95% CI, 1.09-2.47]) as compared with the control group, whereas no association with DOAC intake was observed (aOR, 0.98 [95% CI, 0.29-3.35] and 1.35 [95% CI, 0.72-2.53]). Sensitivity analyses considering only patients within the confirmed therapeutic anticoagulation range did not alter the findings. A study-level meta-analysis incorporating data from 7462 patients (855 VKAs, 318 DOACs, and 6289 controls) from 15 observational cohorts corroborated these observations, yielding an increased rate of sICH in VKA patients (aOR, 1.62 [95% CI, 1.22-2.17]) but not in DOAC patients (aOR, 1.03 [95% CI, 0.60-1.80]). Conclusions- Patients taking VKA have an increased risk of sICH and mortality after mechanical thrombectomy. The lower risk of sICH associated with DOAC may also be noticeable in the acute setting. Improved selection might be advisable in VKA-treated patients. Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT03496064. Systematic Review and Meta-Analysis: CRD42019127464.

Fully automated thromboelastograph TEG 6s to measure anticoagulant effects of direct oral anticoagulants in healthy male volunteers

BACKGROUND

The ability to assess the hemostatic effect of the direct oral anticoagulant (DOACs) may be valuable in clinical situations such as bleeding or thrombosis, before urgent surgery, or reversal of anticoagulation. We sought to assess the anticoagulant effect of DOACs with the new-generation fully automated thrombelastograph TEG 6s using resonance-frequency viscoelasticity measurements and disposable multichannel microfluidic cartridges.

METHODS

A single dose of oral dabigatran 150 mg, rivaroxaban 20 mg, or apixaban 5 mg was given to 9 healthy males. Phlebotomy was performed at 0, 1, and 3 hours after administration of DOAC. TEG parameters were measured using TEG _6s. Concentrations of DOACs were measured using chromogenic assays. The TEG parameters were correlated to the DOAC concentrations.

RESULTS

The reaction time (R) demonstrated the strongest response to DOAC intake. There were no correlations between other TEG parameters and DOAC concentrations. Using the direct thrombin inhibitor (DTI) channel, R was significantly correlated with dabigatran levels (r = 0.94, P < 0.0001). Using the anti-factor Xa (AFXa) channel, R was significantly correlated with rivaroxaban and apixaban levels (r = 0.93 and r = 0.83, respectively; P < 0.0001 for both). R >2.5 minutes for dabigatran (DTI channel), >2.5 minutes for apixaban, and >1.8 minutes for rivaroxaban (AFXa channel) were associated with 100% sensitivity and ≥ 90% specificity to detect DOAC levels of ≥ 50 ng/mL.

CONCLUSION

We have demonstrated that TEG _6s R has significant correlation with DOAC blood concentrations and has potential for monitoring the DOAC's effect on hemostasis with reasonable sensitivity in the small sample analyzed. This novel technology is easy to use on a small volume of whole blood without requiring a specialized laboratory. Further study is warranted to correlate R with clinical outcomes.

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.

Characteristics in Non-Vitamin K Antagonist Oral Anticoagulant-Related Intracerebral Hemorrhage

Background and Purpose- Given inconclusive studies, it is debated whether clinical and imaging characteristics, as well as functional outcome, differ among patients with intracerebral hemorrhage (ICH) related to vitamin K antagonists (VKA) versus non-vitamin K antagonist (NOAC)-related ICH. Notably, clinical characteristics according to different NOAC agents and dosages are not established. Methods- Multicenter observational cohort study integrating individual patient data of 1328 patients with oral anticoagulation-associated ICH, including 190 NOAC-related ICH patients, recruited from 2011 to 2015 at 19 tertiary centers across Germany. Imaging, clinical characteristics, and 3-months modified Rankin Scale (mRS) outcomes were compared in NOAC- versus VKA-related ICH patients. Propensity score matching was conducted to adjust for clinically relevant differences in baseline parameters. Subgroup analyses were performed regarding NOAC agent, dosing and present clinically relevant anticoagulatory activity (last intake <12h/24h or NOAC level >30 ng/mL). Results- Despite older age in NOAC patients, there were no relevant differences in clinical and hematoma characteristics between NOAC- and VKA-related ICH regarding baseline hematoma volume (median [interquartile range]: NOAC, 14.7 [5.1-42.3] mL versus VKA, 16.4 [5.8-40.6] mL; P=0.33), rate of hematoma expansion (NOAC, 49/146 [33.6%] versus VKA, 235/688 [34.2%]; P=0.89), and the proportion of patients with unfavorable outcome at 3 months (mRS, 4-6: NOAC 126/179 [70.4%] versus VKA 473/682 [69.4%]; P=0.79). Subgroup analyses revealed that NOAC patients with clinically relevant anticoagulatory effect had higher rates of intraventricular hemorrhage (n/N [%]: present 52/109 [47.7%] versus absent 9/35 [25.7%]; P=0.022) and hematoma expansion (present 35/90 [38.9%] versus absent 5/30 [16.7%]; P=0.040), whereas type of NOAC agent or different NOAC-dosing regimens did not result in relevant differences in imaging characteristics or outcome. Conclusions- If effectively anticoagulated, there are no differences in hematoma characteristics and functional outcome among patients with NOAC- or VKA-related ICH. Clinical Trial Registration- URL: https://www.clinicaltrials.gov . Unique identifier: NCT03093233.

Direct oral anticoagulants versus vitamin K antagonists after recent ischemic stroke in patients with atrial fibrillation

Objective

We compared outcomes after treatment with direct oral anticoagulants (DOACs) and vitamin K antagonists (VKAs) in patients with atrial fibrillation (AF) and a recent cerebral ischemia.

Methods

We conducted an individual patient data analysis of seven prospective cohort studies. We included patients with AF and a recent cerebral ischemia (<3 months before starting oral anticoagulation) and a minimum follow‐up of 3 months. We analyzed the association between type of anticoagulation (DOAC versus VKA) with the composite primary endpoint (recurrent ischemic stroke [AIS], intracerebral hemorrhage [ICH], or mortality) using mixed‐effects Cox proportional hazards regression models; we calculated adjusted hazard ratios (HRs) with 95% confidence intervals (95% CIs).

Results

We included 4,912 patients (median age, 78 years [interquartile range {IQR}, 71–84]; 2,331 [47.5%] women; median National Institute of Health Stroke Severity Scale at onset, 5 [IQR, 2–12]); 2,256 (45.9%) patients received VKAs and 2,656 (54.1%) DOACs. Median time from index event to starting oral anticoagulation was 5 days (IQR, 2–14) for VKAs and 5 days (IQR, 2–11) for DOACs (p = 0.53). There were 262 acute ischemic strokes (AISs; 4.4%/year), 71 intracranial hemorrrhages (ICHs; 1.2%/year), and 439 deaths (7.4%/year) during the total follow‐up of 5,970 patient‐years. Compared to VKAs, DOAC treatment was associated with reduced risks of the composite endpoint (HR, 0.82; 95% CI, 0.67–1.00; p = 0.05) and ICH (HR, 0.42; 95% CI, 0.24–0.71; p < 0.01); we found no differences for the risk of recurrent AIS (HR, 0.91; 95% CI, 0.70–1.19; p = 0.5) and mortality (HR, 0.83; 95% CI, 0.68–1.03; p = 0.09).

Interpretation

DOAC treatment commenced early after recent cerebral ischemia related to AF was associated with reduced risk of poor clinical outcomes compared to VKA, mainly attributed to lower risks of ICH. ANN NEUROL 2019;85:823–834.

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.

Atrial fibrillation and stroke: a practical guide

Neurologists and stroke physicians will be familiar with atrial fibrillation as a major cause of ischaemic stroke, and the role of anticoagulation in preventing cardioembolic stroke. However, making decisions about anticoagulation for individual patients remains a difficult area of clinical practice, balancing the serious risk of ischaemic stroke against that of major bleeding, particularly intracranial haemorrhage. Atrial fibrillation management requires interdisciplinary collaboration with colleagues in cardiology and haematology. Recent advances, especially the now-widespread availability of direct oral anticoagulants, have brought opportunities to improve stroke care while posing new challenges. This article gives an overview of the contemporary diagnosis and management of atrial fibrillation, and the associated evidence base. Where there is uncertainty, we describe our own approach to these areas, while highlighting ongoing research that will likely guide future practice.

Rivaroxaban plasma levels in patients admitted for bleeding events: insights from a prospective study

Background

Serious bleeding events have been frequently described in patients taking direct oral anticoagulants (DOAC). In secondary analyses of phase 3 trials, DOAC plasma concentrations were shown to correlate with bleeding outcomes. This study aimed to describe rivaroxaban plasma levels in patients admitted to the emergency department (ED) for bleeding events. For each patient, risk factors for experiencing bleeding events were also investigated.

Methods

This analysis was part of an observational study conducted in the ED of two teaching hospitals. Plasma samples from 10 rivaroxaban-treated patients admitted for bleeding events were collected. Rivaroxaban plasma concentrations were determined by calibrated chromogenic anti-Xa assay. The measured rivaroxaban levels were then extrapolated at trough using a published population pharmacokinetic (PopPK) model, and compared to on-therapy ranges observed in large clinical trials. For each patient, clinical, medication and ABCB1 genotype data were collected.

Results

Rivaroxaban measurements varied from 5 to 358 ng/ml, with a post-intake delay ranging from 9 to 38 h. At trough, estimated plasma concentrations were between 12 and 251 ng/ml (median value 94 ng/ml). Four patients had higher-than-expected rivaroxaban levels. Inadequate dose regimen, excessive alcohol consumption and lack of treatment reassessment were observed in several patients. Half of patients were taking ≥1 drug with potential pharmacokinetics interactions (e.g. amiodarone, diltiazem), while half of patients were taking ≥1 drug increasing the risk of bleeding. All 3 patients with available genotyping data and higher-than-expected rivaroxaban levels were heterozygous or homozygous mutated for the ABCB1 1236C > T, 2677G > T, 3435 C > T and rs4148738 single nucleotide polymorphisms (SNP).

Conclusions

Rivaroxaban patients admitted to the ED for bleeding events showed highly variable plasma concentrations. This analysis underlines the usefulness of rapid DOAC measurement and the value of PopPK models to estimate concentrations at trough in a context where the post-intake delay is unmanageable. Close patient follow-up, including renal function assessment and drug interactions review, is essential for bleeding risk minimization.

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.

Dabigatran Plasma Measurement to Guide the Management of Acute Bleeding and Thrombotic Complications

Oral anticoagulant therapy is recommended for the prevention and treatment of venous thromboembolism and to prevent stroke in non-valvular atrial fibrillation. Until a few years ago, vitamin K antagonists were the only drugs available, but direct oral anticoagulants have recently been introduced into clinical practice for the same clinical indications. Unlike the situation with VKAs, fixed-dose administration was proposed for DOACs, without the necessity for routine laboratory monitoring. However, in clinical practice a high inter-variability in DOAC plasma levels, independently of the type of drug and patient characteristics, was observed and the importance of measuring DOAC anticoagulant activity to support treatment decisions has therefore been recognized. We describe two clinical cases in order to highlight the role and importance of dabigatran-specific measurements to guide patient management in case of major complications.

LEARNING POINT

Direct oral anticoagulants (DOACs) have been used in clinical practice at fixed doses without laboratory monitoring.However, the importance of measuring DOAC anticoagulant activity to support treatment decisions, particularly in emergency conditions, has been recognized.The clinical value of DOAC measurement is highlighted in the two described cases where the anticoagulation level was taken into consideration when deciding on treatment.