Unstable angina non ST elevation myocardial infarction aspirin therapy
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Unstable angina / NSTEMI Microchapters |
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Differentiating Unstable Angina/Non-ST Elevation Myocardial Infarction from other Disorders |
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Special Groups |
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Diagnosis |
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Laboratory Findings |
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Treatment |
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Antitplatelet Therapy |
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Additional Management Considerations for Antiplatelet and Anticoagulant Therapy |
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Risk Stratification Before Discharge for Patients With an Ischemia-Guided Strategy of NSTE-ACS |
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Mechanical Reperfusion |
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Discharge Care |
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Case Studies |
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to Hospitals Treating Unstable angina non ST elevation myocardial infarction aspirin therapy |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editors-in-Chief: Varun Kumar, M.B.B.S.; Lakshmi Gopalakrishnan, M.B.B.S.; Smita Kohli, M.D.
Overview
Antiplatelet therapy plays a major role in the management of unstable angina/NSTEMI. This class of medication is directed towards one of the following three pathways: decreasing thromboxane A2 formation (Aspirin), inhibiting the P2Y12 component of the adenosine diphosphate (ADP) receptor pathway (thienopyridines), direct inhibitors of platelet aggregation (GP IIb/IIIa inhibitors).
Aspirin
Mechanism of Benefit
- One of the medications which has consistently been shown to reduce mortality in ACS or CAD patients is ASA.
Clinical Trial Data
Until recently, no trial had directly compared the efficacy of different doses of ASA in patients who present with Unstable angina / NSTEMI.
- CURRENT OASIS 7 trial, which was a randomized, multicenter, multinational trial enrolling 25,087 patients with ACS showed no difference in cardiovascular outcomes of death from MI or stroke between low dose aspirin (75-100mg) compared to high dose aspirin (300-325mg) at the end of 30 days.
- The Second International Study of Infarct Survival (ISIS-2) trial[1] led to the recommendation that ASA be initiated immediately in the ED once the diagnosis of ACS is made or suspected. Aspirin therapy can also be initiated in prehospital setting when ACS is suspected.
- For safety (e.g., gastrointestinal bleeding), a couple of large observational studies have found that the rate of bleeding appears to be lower with low-dose aspirin (75-100mg daily) as compared with high dose aspirin (325 mg daily) in patients receiving medical therapy, percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG).
Dosing
- Non enteric coated formulations are preferred due to rapid buccal absorption.
- On the basis of previous randomized trials, the current recommendation for initial dose of aspirin is 162-325mg.
- After an initial loading dose of 162 to 325 mg, a dose of 75 to 100mg daily appears sufficient.
- On the basis of current available data, lifelong continuation of aspirin should be encouraged unless a contraindication develops.
- In patients who have an allergy or who cannot tolerate aspirin, use of clopidogrel is recommended.
References
- ↑ "Randomised trial of intravenous streptokinase, oral aspirin, both, or neither among 17,187 cases of suspected acute myocardial infarction: ISIS-2. ISIS-2 (Second International Study of Infarct Survival) Collaborative Group". Lancet. 2 (8607): 349–60. 1988. PMID 2899772. Unknown parameter
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