Early versus delayed anticoagulation treatment for people with non-valvular atrial fibrillation-related acute ischaemic stroke

OBJECTIVES

This is a protocol for a Cochrane Review (intervention). The objectives are as follows: To assess the benefits and risks of early versus late initiation of oral anticoagulation (vitamin K antagonists or NOACs) in people with non-valvular atrial fibrillation-related ischaemic stroke.

Early Versus Delayed Oral Anticoagulation in Patients With Acute Ischemic Stroke Due to Atrial Fibrillation: A Meta-Analysis

The aim of this study was to compare the safety and efficacy of early oral anticoagulation with delayed anticoagulant therapy in patients who have had a recent stroke and have atrial fibrillation (AF). This meta-analysis was conducted following the Preferred Reporting Items for Systemic Reviews and Meta-analyses (PRISMA) statement. The literature search was independently performed by two authors. We searched PubMed and Scopus using search strings that included the following terms: "stroke," "atrial fibrillation," "oral anticoagulants," "recurrent stroke," and "intracerebral hemorrhage." Our search spanned from the inception of databases to May 25, 2023. The primary outcome assessed in this study was the composite efficacy outcome (as defined by individual studies). Recurrent ischemic stroke (IS), intracranial hemorrhage (ICH), and death from any cause were assessed as secondary outcomes. For safety analysis, bleeding events were compared between the two study groups. We included five articles in this meta-analysis, comprising a total of 7958 patients (including 3793 in the early treatment group and 4165 in the delayed treatment group). Pooled analysis showed that the risk of composite efficacy outcome (RR: 0.69, 95% CI: 0.51-0.93, p-value: 0.01) and recurrent ischemic stroke (RR: 0.71, 95% CI: 0.53-0.94, p-value: 0.02) were lower in the early treatment group. However, no significant differences were observed between the two groups in terms of all-cause mortality, intracranial hemorrhage, or bleeding events. In light of the findings, healthcare professionals should carefully evaluate the risks and benefits of early versus delayed DOAC treatment in individual patients, considering factors such as stroke severity, bleeding risk, and patient preferences.

Anticoagulants for acute ischaemic stroke

BACKGROUND

Stroke is the third leading cause of early death worldwide. Most ischaemic strokes are caused by a blood clot blocking an artery in the brain. Patient outcomes might be improved if they are offered anticoagulants that reduce their risk of developing new blood clots and do not increase the risk of bleeding. This is an update of a Cochrane Review first published in 1995, with updates in 2004, 2008, and 2015.

OBJECTIVES

To assess the effectiveness and safety of early anticoagulation (within the first 14 days of onset) for people with acute presumed or confirmed ischaemic stroke. Our hypotheses were that, compared with a policy of avoiding their use, early anticoagulation would be associated with: • reduced risk of death or dependence in activities of daily living a few months after stroke onset; • reduced risk of early recurrent ischaemic stroke; • increased risk of symptomatic intracranial and extracranial haemorrhage; and • reduced risk of deep vein thrombosis and pulmonary embolism.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (August 2021); the Cochrane Database of Systematic Reviews (CDSR); the Cochrane Central Register of Controlled Trials (CENTRAL; 2021, Issue 7), in the Cochrane Library (searched 5 August 2021); MEDLINE (2014 to 5 August 2021); and Embase (2014 to 5 August 2021). In addition, we searched ongoing trials registries and reference lists of relevant papers. For previous versions of this review, we searched the register of the Antithrombotic Trialists' (ATT) Collaboration, consulted MedStrategy (1995), and contacted relevant drug companies.

SELECTION CRITERIA

Randomised trials comparing early anticoagulant therapy (started within two weeks of stroke onset) with control in people with acute presumed or confirmed ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed trial quality, and extracted data. We assessed the overall certainty of the evidence for each outcome using RoB1 and GRADE methods.

MAIN RESULTS

We included 28 trials involving 24,025 participants. Quality of the trials varied considerably. We considered some studies to be at unclear or high risk of selection, performance, detection, attrition, or reporting bias. Anticoagulants tested were standard unfractionated heparin, low-molecular-weight heparins, heparinoids, oral anticoagulants, and thrombin inhibitors. Over 90% of the evidence is related to effects of anticoagulant therapy initiated within the first 48 hours of onset. No evidence suggests that early anticoagulation reduced the odds of death or dependence at the end of follow-up (odds ratio (OR) 0.98, 95% confidence interval (CI) 0.92 to 1.03; 12 RCTs, 22,428 participants; high-certainty evidence). Similarly, we found no evidence suggesting that anticoagulant therapy started within the first 14 days of stroke onset reduced the odds of death from all causes (OR 0.99, 95% CI 0.90 to 1.09; 22 RCTs, 22,602 participants; low-certainty evidence) during the treatment period. Although early anticoagulant therapy was associated with fewer recurrent ischaemic strokes (OR 0.75, 95% CI 0.65 to 0.88; 12 RCTs, 21,665 participants; moderate-certainty evidence), it was also associated with an increase in symptomatic intracranial haemorrhage (OR 2.47; 95% CI 1.90 to 3.21; 20 RCTs, 23,221 participants; moderate-certainty evidence). Similarly, early anticoagulation reduced the frequency of symptomatic pulmonary emboli (OR 0.60, 95% CI 0.44 to 0.81; 14 RCTs, 22,544 participants; high-certainty evidence), but this benefit was offset by an increase in extracranial haemorrhage (OR 2.99, 95% CI 2.24 to 3.99; 18 RCTs, 22,255 participants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Since the last version of this review, four new relevant studies have been published, and conclusions remain consistent. People who have early anticoagulant therapy after acute ischaemic stroke do not demonstrate any net short- or long-term benefit. Treatment with anticoagulants reduced recurrent stroke, deep vein thrombosis, and pulmonary embolism but increased bleeding risk. Data do not support the routine use of any of the currently available anticoagulants for acute ischaemic stroke.

Oral Anticoagulation Timing in Patients with Acute Ischaemic Stroke and Atrial Fibrillation

BACKGROUND AND PURPOSE

Oral anticoagulants (OACs) prevent stroke recurrence and vascular embolism in patients with acute ischaemic stroke (AIS) and atrial fibrillation (AF). Current guidance recommends a "1-3-6-12 day"' rule to resume OACs after AIS, based mainly on empirical consensus. This study investigated the suitability of guideline-recommended timing for OAC initiation.

METHODS

To overcome immortal time bias, we emulated a sequence of randomized placebo-controlled trials and constructed 90 propensity score-matched cohorts of 12,307 patients with AF and AIS from 2012 to 2016. We compared the risk of composite effectiveness and safety outcome in the early vs no OAC use group and in the delayed vs no OAC use. Indirect comparison between early and delayed use was conducted using a network meta-analysis.

RESULTS

Across the groups of AIS severity, the risks of composite outcome or effectiveness outcome were lower in the OAC use group than the no use group and the risks were similar between the early and delayed use groups. In patients with severe AIS, those receiving early OACs use had an increased risk of safety outcome, with HR of 2.10 (CI: 1.13-3.92) compared with those without OAC use, and HR of 1·44 (CI: 0·99-2·09) compared with those receiving delayed use.

CONCLUSIONS

In AF patients with severe AIS, early OAC use before the guideline-recommended days appeared to increase the risk of bleeding events, although the OAC initiation time seemed not to affect the risk of serious vascular events. The optimal severity-specific timing for OAC initiation after AIS requires further evaluation.

Early Apixaban Use Following Stroke in Patients With Atrial Fibrillation: Results of the AREST Trial

BACKGROUND AND PURPOSE

It is unknown when to start anticoagulation after acute ischemic stroke (AIS) from atrial fibrillation (AF). Early anticoagulation may prevent recurrent infarctions but may provoke hemorrhagic transformation as AF strokes are typically larger and hemorrhagic transformation-prone. Later anticoagulation may prevent hemorrhagic transformation but increases risk of secondary stroke in this time frame. Our aim was to compare early anticoagulation with apixaban in AF patients with stroke or transient ischemic attack (TIA) versus warfarin administration at later intervals.

METHODS

AREST (Apixaban for Early Prevention of Recurrent Embolic Stroke and Hemorrhagic Transformation) was an open-label, randomized controlled trial comparing the safety of early use of apixaban at day 0 to 3 for TIA, day 3 to 5 for small-sized AIS (<1.5 cm), and day 7 to 9 for medium-sized AIS (≥1.5 cm, excluding full cortical territory), to warfarin, in a 1:1 ratio at 1 week post-TIA, or 2 weeks post-AIS.

RESULTS

Although AREST ended prematurely after a national guideline focused update recommended direct oral anticoagulants over warfarin for AF, it revealed that apixaban had statistically similar yet generally numerically lower rates of recurrent strokes/TIA (14.6% versus 19.2%, P=0.78), death (4.9% versus 8.5%, P=0.68), fatal strokes (2.4% versus 8.5%, P=0.37), symptomatic hemorrhages (0% versus 2.1%), and the primary composite outcome of fatal stroke, recurrent ischemic stroke, or TIA (17.1% versus 25.5%, P=0.44). One symptomatic intracerebral hemorrhage occurred on warfarin, none on apixaban. Five asymptomatic hemorrhagic transformation occurred in each arm.

CONCLUSIONS

Early initiation of anticoagulation after TIA, small-, or medium-sized AIS from AF does not appear to compromise patient safety. Potential efficacy of early initiation of anticoagulation remains to be determined from larger pivotal trials. Registration: URL: https://www.clinicaltrials.gov/; Unique identifier: NCT02283294.

Dabigatran initiation in patients with non-valvular AF and first acute ischaemic stroke: a retrospective observational study from the SITS registry

BACKGROUND AND OBJECTIVE

The optimal timing for initiation of dabigatran after acute ischaemic stroke (AIS) is not established. We aimed to evaluate initiation timing and clinical outcomes of dabigatran in AIS patients with non-valvular atrial fibrillation (NVAF).

DESIGN

Retrospective study based on prospectively collected data in SITS (Safe Implementation of Treatment in Stroke) Thrombolysis and Thrombectomy Registry from July 2014 to July 2018.

PARTICIPANTS

European NVAF patients (≥18 years) hospitalised after first-ever ischaemic stroke.

SETTING

A multinational, observational monitoring register.

INTERVENTION

Dabigatran initiation within 3 months after the ischaemic stroke.

PRIMARY AND SECONDARY OUTCOMES

The primary outcome was time from first-ever ischaemic stroke (index event) to dabigatran initiation. Additional outcomes included physicians' reasons for delaying dabigatran initiation beyond acute hospital discharge and outcomes within 3 months of index event.

METHODS

We identified patients with NVAF who received dabigatran within 3 months of the index event. We performed descriptive statistics for baseline and demographic data and clinical outcomes after dabigatran initiation.

RESULTS

In total, 1489 patients with NVAF received dabigatran after AIS treated with thrombolysis and/or thrombectomy. Of these, 1240 had available initiation time. At baseline, median age was 75 years; 53% of patients were women, 15% were receiving an oral anticoagulant, 29% acetylsalicylic acid and 4% clopidogrel. Most patients (82%) initiated dabigatran within 14 days after the index event. Patients initiating earlier had lower stroke severity from median NIHSS 8 (IQR 6-13) if initiated within 7 days to NIHSS 15 (9-19) if initiated between 28 days and 3 months. Most common reasons for delaying initiation were haemorrhagic transformation or intracranial haemorrhage, stroke severity and infarct size. Few thrombotic/haemorrhagic events occurred within 3 months after the index event (20 of 926 patients, 2.2% with the available data).

CONCLUSIONS

Our findings, together with previous observational studies, indicate that dabigatran initiated within the first days after an AIS is safe in patients treated with intravenous thrombolysis, endovascular thrombectomy or both.

TRIAL REGISTRATION NUMBER

SITS Thrombolysis and Thrombectomy Registry (NCT03258645).

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.

Non-vitamin K oral anticoagulants (NOACs) in patients with stroke and atrial fibrillation

Patients with atrial fibrillation who had a previous transient ischemic attack or ischemic stroke had a significantly high risk of stroke recurrence and the introduction of oral anticoagulants should be mandatory. However, the long-term use of oral anticoagulants increases the risk of developing all types of intracranial hemorrhages. The advantages of non-vitamin K oral anticoagulants (NOACs) compared to warfarin are that they have a significantly lower risk for hemorrhagic stroke. They are preferred in elderly patients, those with small vessel disease, or those with previous intracerebral hemorrhage. The time of NOACs introduction after an ischemic stroke depends on its severity and the rule "1-3-6-12" days should be applied. The reintroduction of NOACs in patients with atrial fibrillation and previous intracerebral hemorrhage depends on its etiology and should be after about 4-8 weeks if the cardioembolic risk is high and the risk for intracranial hemorrhage small.

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.

Prevalence and Overlap of Potential Embolic Sources in Patients With Embolic Stroke of Undetermined Source

Background

We aimed to assess the prevalence and degree of overlap of potential embolic sources (PES) in patients with embolic stroke of undetermined source (ESUS).

Methods and Results

In a pooled data set derived from 3 prospective stroke registries, patients were categorized in ≥1 groups according to the PES that was/were identified. We categorized PES as follows: atrial cardiopathy, atrial fibrillation diagnosed during follow‐up, arterial disease, left ventricular disease, cardiac valvular disease, patent foramen ovale, and cancer. In 800 patients with ESUS (43.1% women; median age, 67.0 years), 3 most prevalent PES were left ventricular disease, arterial disease, and atrial cardiopathy, which were present in 54.4%, 48.5%, and 45.0% of patients, respectively. Most patients (65.5%) had >1 PES, whereas only 29.7% and 4.8% of patients had a single or no PES, respectively. In 31.1% of patients, there were ≥3 PES present. On average, each patient had 2 PES (median, 2). During a median follow‐up of 3.7 years, stroke recurrence occurred in 101 (12.6%) of patients (23.3 recurrences per 100 patient‐years). In multivariate analysis, the risk of stroke recurrence was higher in the atrial fibrillation group compared with other PES, but not statistically different between patients with 0 to 1, 2, or ≥3 PES.

Conclusions

There is major overlap of PES in patients with ESUS. This may possibly explain the negative results of the recent large randomized controlled trials of secondary prevention in patients with ESUS and offer a rationale for a randomized controlled trial of combination of anticoagulation and aspirin for the prevention of stroke recurrence in patients with ESUS.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02766205.

Timing of anticoagulation after recent ischaemic stroke in patients with atrial fibrillation

BACKGROUND

About 13-26% of all acute ischaemic strokes are related to non-valvular atrial fibrillation, the most common cardiac arrhythmia globally. Deciding when to initiate oral anticoagulation in patients with non-valvular atrial fibrillation is a longstanding, common, and unresolved clinical challenge. Although the risk of early recurrent ischaemic stroke is high in this population, early oral anticoagulation is suspected to increase the risk of potentially harmful intracranial haemorrhage, including haemorrhagic transformation of the infarct. This assumption, and current treatment guidelines, are based on historical, mostly observational data from patients with ischaemic stroke and atrial fibrillation treated with heparins, heparinoids, or vitamin K antagonists (VKAs) to prevent recurrent ischaemic stroke. Randomised controlled trials have subsequently shown that direct oral anticoagulants (DOACs; ie, apixaban, dabigatran, edoxaban, and rivaroxaban) are at least as effective as VKAs in primary and secondary prevention of atrial fibrillation-related ischaemic stroke, with around half the risk of intracranial haemorrhage. However, none of these DOAC trials included patients who had experienced ischaemic stroke recently (within the first few weeks). Clinicians therefore remain uncertain regarding when to commence DOAC administration after acute ischaemic stroke in patients with atrial fibrillation.

RECENT DEVELOPMENTS

Prospective observational studies and two small randomised trials have investigated the risks and benefits of early DOAC-administration initiation (most with a median delay of 3-5 days) in mild-to-moderate atrial fibrillation-associated ischaemic stroke. These studies reported that early DOAC treatment was associated with a low frequency of clinically symptomatic intracranial haemorrhage or surrogate haemorrhagic lesions on MRI scans, whereas later DOAC-administration initiation (ie, >7 days or >14 days after index stroke) was associated with an increased frequency of recurrent ischaemic stroke. WHERE NEXT?: Adequately powered randomised controlled trials comparing early to later oral anticoagulation with DOACs in ischaemic stroke associated with atrial fibrillation are justified to confirm the acceptable safety and efficacy of this strategy. Four such randomised controlled trials (collectively planned to include around 9000 participants) are underway, either using single cutoff timepoints for early versus late DOAC-administration initiation, or selecting DOAC-administration timing according to the severity and imaging features of the ischaemic stroke. The results of these trials should help to establish the optimal timing to initiate DOAC administration after recent ischaemic stroke and whether the timing should differ according to stroke severity. Results of these trials are expected from 2021.