Considering the Role of Heparin and Low-Molecular-Weight Heparins in Acute Ischemic Stroke

Background and Purpose— The utility of parenteral anticoagulation therapy in acute ischemic stroke has engendered much controversy and discussion. Recent studies of low-molecular-weight heparins in multiple acute stroke subtypes have not demonstrated improved outcome or reduced recurrence risk. Beneficial treatment effects may occur in subgroups such as patients with large artery atherothrombotic stroke, but further studies will be needed to prove this possibility. Summary of Review— The benefits of unfractionated intravenous heparin for reducing early stroke recurrence and improving outcome remain to be established, with the current lack of appropriately powered trials in stroke subgroups at high risk for such early recurrence. To most clinicians, the primary reason to use early intravenous anticoagulation is to prevent early stroke recurrence, not to improve outcome of an established stroke. Unfortunately, effects of reduction of recurrent stroke risk may be counterbalanced by a substantial increased risk of intracerebral hemorrhage with intravenous anticoagulation. Conclusions— Unfractionated intravenous heparin should therefore not be used routinely in acute ischemic stroke, but it may be considered in select stroke groups at high risk for early recurrent ischemic events (ie, patients with atrial fibrillation or acute myocardial infarction and large mural thrombi). However, even in these select populations, new clinical trials will be needed to define the risk-benefit ratio.