The safety and efficacy of Heparin and Nadroparin compared to placebo in acute ischemic stroke - pilot study

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.

Short-Term and Long-Term Safety and Efficacy of Treatment of Acute Ischemic Stroke with Low-Molecular-Weight Heparin: Meta-Analysis of 19 Randomized Controlled Trials

OBJECTIVE

Currently, it remains controversial about guidelines for the application of low-molecular-weight heparin (LMWH) in patients with acute ischemic stroke (AIS). Therefore this meta-analysis was carried out, aiming to systematically investigate the short-term and long-term safety and efficacy of LMWH in AIS patients.

METHODS

Three electronic databases-PubMed, Embase database, and Cochrane library-were comprehensively retrieved by 2 investigators independently. Finally, a total of 19 randomized controlled trials were enrolled for analysis. The safety endpoints in this study included all-cause mortality and the risk of bleeding (major, minor, or cerebral hemorrhage). The efficacy endpoints were the prevention of deep vein thrombosis (DVT) and recurrent stroke.

RESULTS

The application of LMWH led to a decreased risk of DVT, and there was no significant association in all-cause mortality or recurrent stroke. According to age-stratified analyses, the risk of all-cause mortality increased by 39% (risk ratio 1.39, 1.03-1.88; I² 0%) in AIS patients aged older than 70 years who used LMWH for 14 days, and there was no significant effect on preventing DVT (risk ratio 0.69, 0.14-3.52; I² 26.4%) in patients aged younger than 70 years old within 3 months. Moreover, enoxaparin and danaparoid were more effective at preventing DVT, regardless of age.

CONCLUSIONS

To sum up, on the basis of limited studies available currently, the early use of LMWH in AIS patients aged older than 70 years should be cautious because it may increase the risk of all-cause mortality. For patients younger than 70 years old, the early use of LMWH significantly reduces the short-term risk of DVT, but there is no significant relationship in the long term. In terms of DVT prevention, enoxaparin and danaparoid are probably more effective. Nonetheless, more future randomized controlled trials are warranted to verify and support this conclusion.

Epigenome-Wide Analyses Identify Two Novel Associations With Recurrent Stroke in the Vitamin Intervention for Stroke Prevention Clinical Trial

DNA methylation, a well-characterized epigenetic modification that is influenced by both environment and genetic variation, has previously been implicated in a number of complex diseases, including cardiovascular disease and stroke. The goal of this study was to evaluate epigenome-wide associations with recurrent stroke and the folate one-carbon metabolism-related trait, plasma homocysteine (hcy). Differential methylation analyses were performed on 473,864 autosomal CpG loci, using Illumina HumanMethylation 450K array data in 180 ischemic stroke cases from the Vitamin Intervention for Stroke Prevention (VISP) clinical trial. Linear regression was used to assess associations between number of strokes prior to VISP enrollment and measures of hcy with degree of methylation (β-values), while logistic regression was used to evaluate recurrent stroke status and incident recurrent stroke associations. All regression analyses were stratified by race. Two differentially methylated CpG sites exceeded epigenome-wide significance (p ≤ 1.055 × 10⁻⁷) for prior number of strokes (PNS) in European Americans. The top locus, cg22812874, was located in the ankyrin repeat and SOCS box containing 10 gene (ASB10; p = 3.4 × 10⁻⁹; β = −0.0308; 95% CI = −0.040, −0.002). Methylation locus cg00340919, located in an intron of the tetratricopeptide repeat domain 37 gene, was also statistically significant (TTC37; p = 8.74 × 10⁻⁸; β = −0.0517; 95% CI = −0.069, −0.034). An additional 138 CpG sites met our threshold for suggestive significance (p ≤ 5 × 10⁻⁵). We evaluated DNA methylation associated with recurrent stroke and hcy phenotypes across the epigenome. Hypermethylation at two CpG sites located in ASB10 and TTC37 was associated with fewer strokes prior to VISP enrollment. Our findings present a foundation for additional epigenome-wide studies, as well as mechanistic studies into epigenetic marks that influence recurrent stroke risk.

Low-molecular-weight heparins or heparinoids versus standard unfractionated heparin for acute ischaemic stroke

BACKGROUND

Low-molecular-weight heparins (LMWHs) and heparinoids are anticoagulants that may have more powerful antithrombotic effects than standard unfractionated heparin (UFH) but a lower risk of bleeding complications. This is an update of the original Cochrane Review of these agents, first published in 2001 and last updated in 2008.

OBJECTIVES

To determine whether antithrombotic therapy with LMWHs or heparinoids is associated with a reduction in the proportion of people who are dead or dependent for activities in daily living compared with UFH.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched February 2017), the Cochrane Central Register of Controlled Trials (CENTRAL: the Cochrane Library Issue 1, 2017), MEDLINE (1966 to February 2017), and Embase (1980 to February 2017). We also searched trials registers to February 2017: ClinicalTrials.gov, EU Clinical Trials Register, Stroke Trials Registry, ISRCTN Registry and the World Health Organization (WHO) International Clinical Trials Registry Platform.

SELECTION CRITERIA

Unconfounded randomised trials comparing LMWH or heparinoids with standard UFH in people with acute ischaemic stroke, in which participants were recruited within 14 days of stroke onset.

DATA COLLECTION AND ANALYSIS

Two review authors independently chose studies for inclusion, assessed risk of bias and trial quality, extracted and analysed the data. Differences were resolved by discussion.

MAIN RESULTS

We included nine trials involving 3137 participants. We did not identify any new trials for inclusion in this updated review. None of the studies reported data on the primary outcome in sufficient detail to enable analysis for the review. Overall, there was a moderate risk of bias in the included studies. Compared with UFH, there was no evidence of an effect of LMWH or heparinoids on death from all causes during the treatment period (96/1616 allocated LMWH/heparinoid versus 78/1486 allocated UFH; odds ratio (OR) 1.06, 95% CI 0.78 to 1.47; 8 trials, 3102 participants, low quality evidence). LMWH or heparinoid were associated with a significant reduction in deep vein thrombosis (DVT) compared with UFH (OR 0.55, 95% CI 0.44 to 0.70, 7 trials, 2585 participants, low quality evidence). However, the number of the major clinical events such as pulmonary embolism (PE) and intracranial haemorrhage was too small to provide a reliable estimate of the effects.

AUTHORS' CONCLUSIONS

Treatment with a LMWH or heparinoid after acute ischaemic stroke appears to decrease the occurrence of DVT compared with standard UFH, but there are too few data to provide reliable information on their effects on other important outcomes, including functional outcome, death and intracranial haemorrhage.