Definitions of the levels of evidence (Class I-IV) and grades of recommendation (Grade A-C) are provided at the end of the Major Recommendations field.
- Patients with acute ischemic stroke presenting within 48 hours of symptom onset should be given aspirin (160 to 325 mg/day) to reduce stroke mortality and decrease morbidity, provided contraindications such as allergy and gastrointestinal bleeding are absent, and the patient has not been or will not be treated with recombinant tissue type plasminogen activator (Grade A). The data are insufficient at this time to recommend the use of any other platelet antiaggregant in the setting of acute ischemic stroke.
- Subcutaneous unfractionated heparin, low molecular weight (LMW) heparins, and heparinoids may be considered for deep vein thrombosis (DVT) prophylaxis in at-risk patients with acute ischemic stroke, recognizing that nonpharmacologic treatments for DVT prevention also exist (Grade A). A benefit in reducing the incidence of pulmonary embolism (PE) has not been demonstrated. The relative benefits of these agents must be weighed against the risk of systemic and intracerebral hemorrhage.
- Although there is some evidence that fixed-dose, subcutaneous, unfractionated heparin reduces early recurrent ischemic stroke, this benefit is negated by a concomitant increase in the occurrence of hemorrhage. Therefore, use of subcutaneous unfractionated heparin is not recommended for decreasing the risk of death or stroke-related morbidity or for preventing early stroke recurrence (Grade A).
- A. Dose-adjusted, unfractionated heparin is not recommended for reducing morbidity, mortality, or early recurrent stroke in patients with acute stroke (i.e., in the first 48 hours) because the evidence indicates it is not efficacious and may be associated with increased bleeding complications (Grade B).
- B. High-dose LMW heparin/heparinoids have not been associated with either benefit or harm in reducing morbidity, mortality, or early recurrent stroke in patients with acute stroke and are, therefore, not recommended for these goals (Grade A).
- Intravenous (IV), unfractionated heparin or high dose LMW heparin/heparinoids are not recommended for any specific subgroup of patients with acute ischemic stroke that is based on any presumed stroke mechanism or location (e.g., cardioembolic, large vessel atherosclerotic, vertebrobasilar, or "progressing" stroke) because data are insufficient (Grade U). Although the LMW heparin dalteparin at high doses may be efficacious in patients with atrial fibrillation, it is not more efficacious than aspirin in this setting. Because aspirin is easier to administer, it, rather than dalteparin, is recommended for the various stroke subgroups (Grade A).
Definitions:
Levels of Evidence
Class I: Evidence provided by a prospective, randomized, controlled clinical trial with masked outcome assessment, in a representative population. The following are required:
- Primary outcome(s) is/are clearly defined.
- Exclusion/inclusion criteria are clearly defined.
- Adequate accounting for drop outs and crossovers with numbers sufficiently low to have minimal potential for bias.
- Relevant baseline characteristics are presented and substantially equivalent among treatment groups, or there is appropriate statistical adjustment for differences.
Class II: Evidence provided by a prospective, matched cohort study in a representative population with masked outcome assessment that meets all of the above OR a randomized controlled trial in a representative population that lacks one of the above criteria.
Class III: Evidence provided by all other controlled trials (including well-defined natural history controls or patients serving as own controls) in a representative population, in which outcome assessment is independent of patient treatment.
Class IV: Evidence from uncontrolled studies, case series, case reports, or expert opinion.
Grade of Recommendation
Grade A. At least one convincing Class I study or at least two consistent, convincing Class II studies.
Grade B. At least one convincing Class II study or at least three convincing Class III studies.
Grade C. At least two convincing and consistent Class III studies.