Dual Antiplatelet Therapy in Acute Transient Ischemic Attack and Minor Stroke
From the School of Medicine and Pharmacology, University of Western Australia, and the Stroke Unit and Department of Neurology, Royal Perth Hospital - both in Perth, WA, Australia.New England Journal of Medicine (Impact Factor: 55.87). 06/2013; 369(1). DOI: 10.1056/NEJMe1305127
Some patients with stroke and transient ischemic attack (TIA) of the brain are at high risk for early recurrent stroke, usually due to arterial thromboembolism.(1),(2) Aspirin reduces the risk of early recurrent stroke by only 12% (95% confidence interval [CI], 3 to 20).(3) Adding clopidogrel to aspirin in patients with acute coronary syndromes reduces the risk of recurrent vascular events by 20% (95% CI, 10 to 28) but increases the risk of major bleeding by 38% (95% CI, 13 to 67).(4) For patients with acute ischemic stroke, who are prone to early spontaneous hemorrhagic transformation of infarcted brain, adding . . .
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ABSTRACT: Hemorrhagic transformation (HT) is a common complication of ischemic stroke that is exacerbated by thrombolytic therapy. Methods to better prevent, predict, and treat HT are needed. In this review, we summarize studies of HT in both animals and humans. We propose that early HT (<18 to 24 hours after stroke onset) relates to leukocyte-derived matrix metalloproteinase-9 (MMP-9) and brain-derived MMP-2 that damage the neurovascular unit and promote blood-brain barrier (BBB) disruption. This contrasts to delayed HT (>18 to 24 hours after stroke) that relates to ischemia activation of brain proteases (MMP-2, MMP-3, MMP-9, and endogenous tissue plasminogen activator), neuroinflammation, and factors that promote vascular remodeling (vascular endothelial growth factor and high-moblity-group-box-1). Processes that mediate BBB repair and reduce HT risk are discussed, including transforming growth factor beta signaling in monocytes, Src kinase signaling, MMP inhibitors, and inhibitors of reactive oxygen species. Finally, clinical features associated with HT in patients with stroke are reviewed, including approaches to predict HT by clinical factors, brain imaging, and blood biomarkers. Though remarkable advances in our understanding of HT have been made, additional efforts are needed to translate these discoveries to the clinic and reduce the impact of HT on patients with ischemic stroke.Journal of Cerebral Blood Flow & Metabolism advance online publication, 27 November 2013; doi:10.1038/jcbfm.2013.203.Journal of cerebral blood flow and metabolism: official journal of the International Society of Cerebral Blood Flow and Metabolism 11/2013; 34(2). DOI:10.1038/jcbfm.2013.203 · 5.41 Impact Factor
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ABSTRACT: Introduction Thromboxane A2 (TXA2) induces platelet aggregation and vasoconstriction, and agents that inhibit TXA2 production or interaction with receptors may exert potential application in stroke therapy. Aim To illustrate the platelet aggregation antagonistic and endothelial protective effect of (E) - 3 - (3 - methoxy - 4 - ((3, 5, 6 - trimethylpyrazin - 2 - yl) methoxy) phenyl) sodium acrylate (MC-002) through TXA2 inhibition and underline mechanisms. Materials and methods Platelets aggregation and thoracic aorta ring contraction of rabbits were induced by U46619. Human umbilical vein endothelial cells (HUVECs) were further applied to explore the protective effect and possible of MC-002 on endothelium when exposing to tumor necrosis factor - α (TNF-α). MTT method was used to assess cell damage, and ELISA analysis was exerted to estimate nitrogen monoxide (NO), endothelin-1 (ET-1), thromboxane B2 (TXB2) and 6-keto-prostaglandin F1α (6-keto-PGF1α) releasing. Fluorescence spectrophotometry was conducted to determine intracellular calcium concentration ([Ca2 +]i), and western blotting method was applied to evaluate the protein expressions of intracellular adhesion molecule-1 (ICAM-1), P-selectin and nuclear factor-kappa B (NF-κB). Results and conclusions TXA2 analog U46619 mediated obvious platelet aggregation and vasoconstriction. MC-002 inhibited platelet aggregation through administration in vivo and incubation with platelet in vitro, and relaxed aorta ring in endothelium dependent manner. MC-002 alleviated cell damage, [Ca2 +]i overload, ET-1 overexcretion and TXB2 activation, but improved NO availability reduction in HUVECs treated with TNF-α. Furthermore, MC-002 downregulated ICAM-1, P-selectin and NF-κB overexpression induced by TNF-α. In conclusion, MC-002 exerted antiplatelet aggregation effect by TXA2 inhibition and relieved inflammatory injury of endothelial cells through NF-κB signal pathway.Thrombosis Research 04/2014; 133(4). DOI:10.1016/j.thromres.2014.01.029 · 2.45 Impact Factor
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ABSTRACT: Background: Antiplatelet agents are the mainstay for secondary prevention of non-cardioembolic stroke. This systematic review examined the safety and efficacy of short-, middle-, and long-term aspirin in combination with clopidogrel as secondary prevention of stroke or transient ischemic attack (TIA) of presumed arterial origin. Methods: PubMed, EmBase, and CENTRAL were searched up to May 2014. Randomized controlled trials (RCTs) that compared aspirin plus clopidogrel versus aspirin or clopidogrel as secondary prevention of stroke or TIA of arterial origin were included. The analyses were stratified into short-term (≤3 months), middle-term (>3 months and <1 year), and long-term (≥1 year). Outcomes were compared using risk ratio (RR) and 95% confidence interval (95% CI). Results: Eight RCTs (20,728 patients) were included in the overall analysis. Compared with aspirin or clopidogrel alone, the complete analysis of all the data indicated that the combination therapy significantly reduced the risk of stroke recurrence (RR, 0.82; 95% CI 0.70-0.96, p = 0.01) and major vascular events (RR, 0.84; 95% CI 0.73-0.96, p < 0.01). But the risk of hemorrhagic stroke (RR, 1.59; 95% CI 1.08-2.33, p = 0.02) and major bleeding (RR, 1.83; 95% CI 1.37-2.45, p < 0.01) was increased. No RCT studied middle-term combination therapy. The analyses were therefore stratified into only two subgroups, short- and long-term treatment. Stratified analysis of short-term treatment showed that relative to monotherapy, the drug combination reduced the risk of stroke recurrence (RR, 0.69; 95% CI 0.59-0.81, p < 0.01) and did not increase the risk of hemorrhagic stroke (RR, 1.23; 95% CI 0.50-3.04, p = 0.65) and major bleeding events (RR, 2.17; 95% CI 0.18-25.71, p = 0.54). Short-term combination therapy was associated with a significantly lower risk of major vascular events (RR, 0.70; 95% CI 0.69 to 0.82, p < 0.01). Stratified analysis of long-term treatment revealed that the combination treatment did not decrease the risk of stroke recurrence (RR, 0.92; 95% CI 0.83-1.03, p = 0.15), but was associated with a significantly higher risk of hemorrhagic stroke (RR, 1.67; 95% CI 1.10-2.56, p = 0.02) and major bleeding events (RR, 1.90; 95% CI 1.46-2.48, p < 0.01). Long-term combination therapy failed to reduce the risk of major vascular events (RR, 0.92; 95% CI 0.84-1.03, p = 0.09). Conclusions: Compared with monotherapy, short-term aspirin in combination with clopidogrel is more effective as secondary prevention of stroke or TIA without increasing the risk of hemorrhagic stroke and major bleeding events. Long-term combination therapy does not reduce the risk of stroke recurrence, and is associated with increased major bleeding events. The clinical applicability of the findings of this systematic review, however, needs to be confirmed in future clinical trials.Cerebrovascular Diseases 12/2014; 39(1):13-22. DOI:10.1159/000369778 · 3.75 Impact Factor
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