Dabigatran Therapy in Acute Ischemic Stroke Patients Without Atrial Fibrillation

Early argatroban and antiplatelet combination therapy in acute non-lacunar single subcortical infarct associated with mild intracranial atherosclerosis

BACKGROUND

Patients with acute non-lacunar single subcortical infarct (SSI) associated with mild intracranial atherosclerosis (ICAS) have a relatively high incidence of early neurological deterioration (END), resulting in unfavorable functional outcomes. Whether the early administration of argatroban and aspirin or clopidogrel within 6-12 h after symptom onset is effective and safe in these patients is unknown.

METHODS

A review of the stroke database of Weihai Municipal Hospital, Cheeloo College of Medicine, Shandong University and Qingdao Center Hospital, Qingdao University Medical College in China was undertaken from May 2017 to January 2020 to identify all patients with non-lacunar SSI caused by ICAS within 6-12 h of symptom onset based on MRI screening. Patients were divided into two groups, one comprising those who received argatroban and mono antiplatelet therapy with aspirin or clopidogrel on admission (argatroban group), and the other those who received dual antiplatelet therapy (DAPT) with aspirin and clopidogrel during hospitalization (DAPT group). The primary outcome was recovery by 90 days after stroke based on a modified Rankin scale (mRS) score (0 to 1). The secondary outcome was END incidence within 120 h of admission. Safety outcomes were intracranial hemorrhage (ICH) and major extracranial bleeding. The probability of clinical benefit (mRS score 0-1 at 90 days) was estimated using multivariable logistic regression analysis.

RESULTS

A total of 304 acute non-lacunar SSI associated with mild ICAS patients were analyzed. At 90 days, 101 (74.2%) patients in the argatroban group and 80 (47.6%) in the DAPT group had an mRS score that improved from 0 to 1 (P < 0.001). The relative risk (95% credible interval) for an mRS score improving from 0 to 1 in the argatroban group was 1.50 (1.05-2.70). END occurred in 10 (7.3%) patients in the argatroban group compared with 37 (22.0%) in the DAPT group (P < 0.001). No patients experienced symptomatic hemorrhagic transformation.

CONCLUSIONS

Early combined administration of argatroban and an antiplatelet agent (aspirin or clopidogrel) may be beneficial for patients with non-lacunar SSI associated with mild ICAS identified by MRI screening and may attenuate progressive neurological deficits.

TRIAL REGISTRATION

Our study is a retrospectively registered trial.

The Role of Thrombin in Brain Injury After Hemorrhagic and Ischemic Stroke

Thrombin is increased in the brain after hemorrhagic and ischemic stroke primarily due to the prothrombin entry from blood either with a hemorrhage or following blood-brain barrier disruption. Increasing evidence indicates that thrombin and its receptors (protease-activated receptors (PARs)) play a major role in brain pathology following ischemic and hemorrhagic stroke (including intracerebral, intraventricular, and subarachnoid hemorrhage). Thrombin and PARs affect brain injury via multiple mechanisms that can be detrimental or protective. The cleavage of prothrombin into thrombin is the key step of hemostasis and thrombosis which takes place in every stroke and subsequent brain injury. The extravascular effects and direct cellular interactions of thrombin are mediated by PARs (PAR-1, PAR-3, and PAR-4) and their downstream signaling in multiple brain cell types. Such effects include inducing blood-brain-barrier disruption, brain edema, neuroinflammation, and neuronal death, although low thrombin concentrations can promote cell survival. Also, thrombin directly links the coagulation system to the immune system by activating interleukin-1α. Such effects of thrombin can result in both short-term brain injury and long-term functional deficits, making extravascular thrombin an understudied therapeutic target for stroke. This review examines the role of thrombin and PARs in brain injury following hemorrhagic and ischemic stroke and the potential treatment strategies which are complicated by their role in both hemostasis and brain.

Dabigatran Treatment of Acute Noncardioembolic Ischemic Stroke

Background and Purpose- Patients with transient ischemic attack (TIA) and minor ischemic stroke are at risk for early recurrent cerebral ischemia. Anticoagulants are associated with reduced recurrence but also increased hemorrhagic transformation (HT). The safety of the novel oral anticoagulant dabigatran in acute stroke has not been evaluated. Methods- DATAS II (Dabigatran Treatment of Acute Stroke II) was a phase II prospective, randomized open label, blinded end point trial. Patients with noncardioembolic stroke/transient ischemic attack (National Institutes of Health Stroke Scale score, ≤9; infarct volume, ≤25 mL) were randomized to dabigatran or aspirin. Magnetic resonance imaging was performed before randomization and repeated at day 30. Imaging end points were ascertained centrally by readers blinded to treatment. The primary end point was symptomatic HT within 37 days of randomization. Results- A total of 305 patients, mean age 66.59±13.21 years, were randomized to dabigatran or aspirin a mean of 42.00±17.31 hours after symptom onset. The qualifying event was a transient ischemic attack in 21%, and ischemic stroke in 79% of patients. Median National Institutes of Health Stroke Scale (interquartile range) was 1 (0-2), and mean infarct volume 3.2±6.5 mL. No symptomatic HT occurred. Asymptomatic petechial HT developed in 11/142 (7.8%) of dabigatran-assigned patients and 5/142 (3.5%) of aspirin-assigned patients (relative risk, 2.301 [95% CI, 0.778-6.802]). Baseline infarct volume predicted incident HT (odds ratio, 1.07 [95% CI, 1.03-1.12]; P=0.0026). Incident covert infarcts on day 30 imaging occurred in 9/142 (6.3%) of dabigatran-assigned and 14/142 (9.8%) of aspirin-assigned patients (relative risk, 0.62 [95% CI, 0.26, 1.48]). Conclusions- Dabigatran was associated with a risk of HT similar to aspirin in acute minor noncardioembolic ischemic stroke/transient ischemic attack. Registration- URL: https://www.clinicaltrials.gov; Unique identifier: NCT02295826.

Guidelines for the Early Management of Patients With Acute Ischemic Stroke: 2019 Update to the 2018 Guidelines for the Early Management of Acute Ischemic Stroke: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association

Background and Purpose- The purpose of these guidelines is to provide an up-to-date comprehensive set of recommendations in a single document for clinicians caring for adult patients with acute arterial ischemic stroke. The intended audiences are prehospital care providers, physicians, allied health professionals, and hospital administrators. These guidelines supersede the 2013 Acute Ischemic Stroke (AIS) Guidelines and are an update of the 2018 AIS Guidelines. Methods- Members of the writing group were appointed by the American Heart Association (AHA) Stroke Council's Scientific Statements Oversight Committee, representing various areas of medical expertise. Members were not allowed to participate in discussions or to vote on topics relevant to their relations with industry. An update of the 2013 AIS Guidelines was originally published in January 2018. This guideline was approved by the AHA Science Advisory and Coordinating Committee and the AHA Executive Committee. In April 2018, a revision to these guidelines, deleting some recommendations, was published online by the AHA. The writing group was asked review the original document and revise if appropriate. In June 2018, the writing group submitted a document with minor changes and with inclusion of important newly published randomized controlled trials with >100 participants and clinical outcomes at least 90 days after AIS. The document was sent to 14 peer reviewers. The writing group evaluated the peer reviewers' comments and revised when appropriate. The current final document was approved by all members of the writing group except when relationships with industry precluded members from voting and by the governing bodies of the AHA. These guidelines use the American College of Cardiology/AHA 2015 Class of Recommendations and Level of Evidence and the new AHA guidelines format. Results- These guidelines detail prehospital care, urgent and emergency evaluation and treatment with intravenous and intra-arterial therapies, and in-hospital management, including secondary prevention measures that are appropriately instituted within the first 2 weeks. The guidelines support the overarching concept of stroke systems of care in both the prehospital and hospital settings. Conclusions- These guidelines provide general recommendations based on the currently available evidence to guide clinicians caring for adult patients with acute arterial ischemic stroke. In many instances, however, only limited data exist demonstrating the urgent need for continued research on treatment of acute ischemic stroke.

Non-Vitamin K Antagonist Oral Anticoagulants in Medical Conditions at High Risk of Thromboembolism beyond Atrial Fibrillation

Non-Vitamin K antagonist oral anticoagulants (NOACs) have been extensively investigated in medical conditions at high risk of venous or arterial thrombosis other than atrial fibrillation (AF), including hip or knee arthroplasty, acute venous thromboembolism (VTE), cancer-associated VTE, acute coronary syndrome (ACS), stable atherosclerotic vascular disease, chronic heart failure, and embolic stroke of undetermined source (ESUS). Two large ESUS trials failed to show the benefit of rivaroxaban or dabigatran, and large randomized controlled trial (RCT) data of NOACs are lacking for another potential candidates of patent foramen ovale-related stroke, acute ischemic stroke, and cerebral venous thrombosis. On the other hand, high quality evidences of NOACs have been compiled for VTE prophylaxis after hip or knee arthroplasty, acute VTE, cancer-associated VTE, and concomitant ACS and AF, which have been reflected in clinical practice guidelines. In addition, RCTs showed the benefit of very low dose rivaroxaban in combination with antiplatelet therapy in patients with ACS and in those with stable cardiovascular disease. This article summarizes the accumulated evidences of NOACs in cardiovascular diseases beyond AF, and aims to inform healthcare providers of optimal regimens tailored to individual medical conditions and help investigators design future clinical trials.

2018 Guidelines for the Early Management of Patients With Acute Ischemic Stroke: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association

BACKGROUND AND PURPOSE

The purpose of these guidelines is to provide an up-to-date comprehensive set of recommendations for clinicians caring for adult patients with acute arterial ischemic stroke in a single document. The intended audiences are prehospital care providers, physicians, allied health professionals, and hospital administrators. These guidelines supersede the 2013 guidelines and subsequent updates.

METHODS

Members of the writing group were appointed by the American Heart Association Stroke Council's Scientific Statements Oversight Committee, representing various areas of medical expertise. Strict adherence to the American Heart Association conflict of interest policy was maintained. Members were not allowed to participate in discussions or to vote on topics relevant to their relations with industry. The members of the writing group unanimously approved all recommendations except when relations with industry precluded members voting. Prerelease review of the draft guideline was performed by 4 expert peer reviewers and by the members of the Stroke Council's Scientific Statements Oversight Committee and Stroke Council Leadership Committee. These guidelines use the American College of Cardiology/American Heart Association 2015 Class of Recommendations and Levels of Evidence and the new American Heart Association guidelines format.

RESULTS

These guidelines detail prehospital care, urgent and emergency evaluation and treatment with intravenous and intra-arterial therapies, and in-hospital management, including secondary prevention measures that are appropriately instituted within the first 2 weeks. The guidelines support the overarching concept of stroke systems of care in both the prehospital and hospital settings.

CONCLUSIONS

These guidelines are based on the best evidence currently available. In many instances, however, only limited data exist demonstrating the urgent need for continued research on treatment of acute ischemic stroke.

Management of acute stroke in patients on oral anticoagulants

PURPOSE OF REVIEW

An increasing number of patients are receiving oral anticoagulants. Since non-vitamin K antagonist oral anticoagulants (NOACs) were approved, primary prevention of ischemic stroke has become simpler. However, managing ischemic stroke and intracerebral hemorrhage while on oral anticoagulation (OAC) has become more complex. This review covers the latest developments in managing ischemic and hemorrhagic stroke in patients receiving vitamin K antagonists (VKA) and NOACs.

RECENT FINDINGS

Testing coagulation in patients with acute ischemic stroke and receiving NOACs is complex, and observational data challenge guideline recommendations. Initial registry and cohort data support the safety of endovascular therapy despite OAC. In intracerebral hemorrhage, rapid reversal of VKA can be achieved better with prothrombin complex concentrates than with fresh frozen plasma. Furthermore, rapid reversal seems to be associated with less hematoma expansion and better functional outcome. In addition, new evidence strongly supports resuming OAC after intracerebral hemorrhage. The unfavorable properties of NOAC-related intracerebral hemorrhage are similar to those associated with VKA.

SUMMARY

Translation of recent findings might improve both outcome in acute ischemic and hemorrhagic stroke in patients on oral anticoagulants and help refine clinical management. Data from randomized clinical trials are scarce.

Timing of anticoagulation therapy in patients with acute ischaemic stroke and atrial fibrillation

In patients with acute stroke and atrial fibrillation (AF), the risk of early recurrence has been reported to range between 0.1% and 1.3% per day. Anticoagulants are the most effective therapy for the prevention of recurrent ischaemic stroke in these patients, but randomised clinical trials have failed to produce any evidence supporting the administration of heparin within 48 hours from stroke onset as it has been associated with a non-significant reduction in the recurrence of ischaemic stroke, no substantial reduction in death and disability, and an increase in intracranial bleeding. As early haemorrhagic transformation is a major concern in the acute phase of stroke patients with AF, determining the optimal time to start anticoagulant therapy is essential. This review which focuses on the epidemiology of recurrent ischaemic stroke and haemorrhagic transformation in patients with acute ischaemic stroke and AF, proposes a model for decision making on optimal timing for initiating anticoagulation, based on currently available evidence.

Dabigatran following acute transient ischemic attack and minor stroke II (DATAS II)

Rationale

Patients with transient ischemic attack or minor stroke are at high risk of early recurrent cerebrovascular events. Anticoagulation with heparin or warfarin acutely after ischemic stroke is at least as efficacious as aspirin for preventing recurrent events but is associated with an increased risk of clinical worsening due to hemorrhagic transformation.

Aim and hypothesis

We aim to demonstrate the safety of early anticoagulation with dabigatran, an oral direct thrombin inhibitor, in acute cerebrovascular syndrome patients. The primary hypothesis is that symptomatic hemorrhagic transformation rates in dabigatran and aspirin-treated patients will be similar.

Sample size estimates

At least 136 participants in two groups required to demonstrate an absolute between-group difference in the rate of hemorrhagic transformation of 5.6% with 80% power, assuming alpha = 5%.

Methods and design

A randomized, multicenter open-label clinical trial (NCT02295826). Three-hundred participants with a transient ischemic attack/ischemic stroke (National Institutes of Health Stroke Scale ≤ 9) will undergo magnetic resonance imaging within 72 h of symptom onset and will be randomized to aspirin 81 mg daily or dabigatran 150 mg twice daily for 30 days. Participants undergo repeat magnetic resonance imaging at 30 days and clinical assessment to 90 days.

Study outcomes

The primary outcome is the symptomatic hemorrhagic transformation rate. Secondary outcomes include recurrent stroke and new ischemic lesions on repeat magnetic resonance imaging.

Discussion

This study will determine the safety of early anticoagulation with dabigatran in patients with acute transient ischemic attack/ischemic stroke and will inform the design of a phase III randomized trial aimed at demonstrating reduced recurrent early ischemic events after acute transient ischemic attack/stroke.

A Linear Temporal Increase in Thrombin Activity and Loss of Its Receptor in Mouse Brain following Ischemic Stroke

BACKGROUND

Brain thrombin activity is increased following acute ischemic stroke and may play a pathogenic role through the protease-activated receptor 1 (PAR1). In order to better assess these factors, we obtained a novel detailed temporal and spatial profile of thrombin activity in a mouse model of permanent middle cerebral artery occlusion (pMCAo).

METHODS

Thrombin activity was measured by fluorescence spectroscopy on coronal slices taken from the ipsilateral and contralateral hemispheres 2, 5, and 24 h following pMCAo (n = 5, 6, 5 mice, respectively). Its spatial distribution was determined by punch samples taken from the ischemic core and penumbra and further confirmed using an enzyme histochemistry technique (n = 4). Levels of PAR1 were determined using western blot.

RESULTS

Two hours following pMCAo, thrombin activity in the stroke core was already significantly higher than the contralateral area (11 ± 5 vs. 2 ± 1 mU/ml). At 5 and 24 h, thrombin activity continued to rise linearly (r = 0.998, p = 0.001) and to expand in the ischemic hemisphere beyond the ischemic core reaching deleterious levels of 271 ± 117 and 123 ± 14 mU/ml (mean ± SEM) in the basal ganglia and ischemic cortex, respectively. The peak elevation of thrombin activity in the ischemic core that was confirmed by fluorescence histochemistry was in good correlation with the infarcts areas. PAR1 levels in the ischemic core decreased as stroke progressed and thrombin activity increased.

CONCLUSION

In conclusion, there is a time- and space-related increase in brain thrombin activity in acute ischemic stroke that is closely related to the progression of brain damage. These results may be useful in the development of therapeutic strategies for ischemic stroke that involve the thrombin-PAR1 pathway in order to prevent secondary thrombin related brain damage.

Haemorrhagic Transformation after Ischaemic Stroke in Patients Taking Non-vitamin K Antagonist Oral Anticoagulants

Background and Purpose

To evaluate the frequency and outcome of haemorrhagic transformation (HT) after ischaemic stroke in patients treated with non-vitamin K antagonist oral anticoagulants (NOACs).

Methods

Patients with stroke on treatment with a NOAC were prospectively enrolled in this multicentre observational study between February 2012 and 2015. Brain imaging at admission and follow-up imaging until day 7 were reviewed for HT. Functional outcome was assessed by the modified Rankin scale (mRS) before the index event, at discharge, and at 3-months.

Results

231 patients without recanalisation therapy (no-RT), and 32 patients with RT were eligible for analysis. Any HT was present at admission in 9/231 no-RT patients (3.9%, 95% CI 2.0 to 7.3) and in none of the patients with RT. In patients with follow-up imaging (no-RT, n=129, and RT, n=32), HT was present in 14.0% (no-RT; 95% CI, 8.9 to 21.1), and 40.6% (RT, 95% CI, 25.5 to 57.8), respectively. After adjustment for stroke severity, this difference between the no-RT and RT groups became non-significant. Symptomatic ICH was observed in 1 patient per group. HT was not associated with unfavourable outcome (mRS 3-6) at 3-months in multivariable analysis. Resumption of OAC after stroke was delayed in patients with HT compared to those without (15 d [IQR, 5–26] vs. 1 d [0–4], P<0.001).

Conclusions

The frequency and severity of HT after stroke on NOAC appears similar to previous reports for vitamin K antagonists and no anticoagulation. Whether asymptomatic HT should delay resumption of preventive anticoagulation requires further investigation.

Thrombolysis and thrombectomy in patients treated with dabigatran with acute ischemic stroke: Expert opinion

Systemic thrombolysis with rt-PA is contraindicated in patients with acute ischemic stroke anticoagulated with dabigatran. This expert opinion provides guidance on the use of the specific reversal agent idarucizumab followed by rt-PA and/or thrombectomy in patients with ischemic stroke pre-treated with dabigatran. The use of idarucizumab followed by rt-PA is covered by the label of both drugs.

Novel oral anticoagulant management issues for the stroke clinician

BACKGROUND

Four nonvitamin K antagonist oral anticoagulants (NOACs) are approved for stroke prevention in patients with nonvalvular atrial fibrillation (NVAF).

AIMS

In this review, we assemble available evidence for the best management of ischemic and hemorrhagic stroke patients in the context of NOAC use.

SUMMARY OF REVIEW

NOACs provide predictable anticoagulation with fixed dosages. The direct thrombin inhibitor dabigatran and direct factor Xa inhibitors apixaban, edoxaban, and rivaroxaban are all noninferior to warfarin for the prevention of ischemic stroke and systemic embolism and are associated with reduced incidence of intracranial hemorrhage. While these agents offer treatment options for NVAF patients, they also present challenges specific to the clinician managing cerebrovascular disease patients.

CONCLUSIONS

We summarize available evidence and current approaches to the initiation, dosing, monitoring and potential reversal of NOACs in stroke patients.

Early Initiation of Anticoagulation with Direct Oral Anticoagulants in Patients after Transient Ischemic Attack or Ischemic Stroke

BACKGROUND

Direct oral anticoagulants (DOACs) are increasingly used for secondary prevention of cardioembolic stroke. While DOACs are associated with a long-term reduced risk of intracranial hemorrhage compared to vitamin K antagonists, pivotal trials avoided the very early period after stroke and few data exist on early initiation of DOAC therapy post stroke.

METHODS

We retrospectively analyzed data from our prospective database of all consecutive transient ischemic attack (TIA) or ischemic stroke patients with atrial fibrillation treated with DOACs during hospital stay. As per our institutional treatment algorithm for patients with cardioembolic ischemia DOACs are started immediately in TIA and minor stroke (group 1), within days 3-5 in patients with infarcts affecting one third or less of the middle cerebral artery, the anterior cerebral artery, or the posterior cerebral artery territories (group 2) as well as in infratentorial stroke (group 3) and after 1-2 weeks in patients with large infarcts (>⅓MCA territory, group 4). We investigated baseline characteristics, time to initiation of DOAC therapy after symptom onset, and hemorrhagic complications.

RESULTS

In 243 included patients, administration of DOAC was initiated 40.5 hours (interquartile range [IQR] 23.0-65.5) after stroke onset in group 1 (n = 41) and after 76.7 hours (IQR 48.0-134.0), 108.4 hours (IQR 67.3-176.4), and 161.8 hours (IQR 153.9-593.8) in groups 2-4 (n = 170, 28, and 4), respectively. Two cases of asymptomatic intracranial hemorrhage (.8%) and 1 case of symptomatic intracranial hemorrhage (.4%) were observed, both in group 2.

CONCLUSIONS

No severe safety issues were observed in early initiation of DOACs for secondary prevention after acute stroke in our in-patient cohort.

Real Data on Effectiveness, Tolerability and Safety of New Oral Anticoagulant Agents: Focus on Dabigatran

Vitamin K-dependent antagonists (VKAs) are the most commonly used oral anticoagulants. Non-VKA oral anticoagulants (NOACs), directly target factor IIa (dabigatran) or Xa (rivaroxaban, apixaban, and edoxaban) have predictable pharmacological effects and relatively few drug and food interactions compared with VKA. Among NOACs, dabigatran has been extensively tested for stroke prevention in patients with non-valvular atrial fibrillation eligible for oral anticoagulation with VKA. Dabigatran is at least as effective as warfarin at preventing stroke with advantages of less serious bleeding except for gastrointestinal bleeding, which occurs more often than with warfarin. The findings of dabigatran use in randomized trials, post market registries and specific clinical settings are discussed in this article.