Heparin in Stroke: Not for Most, but the Controversy Lingers
Few issues in stroke management ignite as much passion as the role of heparin. As outlined by both authors, we are now in the more fortunate position of having more evidence than ever before on its usefulness and hazards. As indicated by Sandercock, much of this evidence suggests that a small reduction in recurrent stroke is outweighed by an increased risk of cerebral hemorrhage. Further, the risk of early recurrent embolism in atrial fibrillation (one of the most common former indications for intravenous heparin) appears to be lower than was originally believed. While there have been major contributions to the evidence base by trials such as IST, TOAST, and others, there is still no large published trial of monitored intravenous, unfractionated heparin in acute ischemic stroke.
Pleasingly, the recent increase in the total evidence base has most likely reduced the somewhat indiscriminate use of intravenous heparin worldwide after onset of ischemic stroke. To reinforce this trend, we agree with both Sandercock and Caplan that indiscriminate use of heparin should certainly be discouraged.
However, there are still important gaps in the evidence base. These include the role of anticoagulation in patients with high-grade large artery stenosis and repeated events, or minor established strokes. Similarly, there is uncertainty about the role of acute anticoagulation in patients with high-risk cardiac lesions (eg, atrial or ventricular thrombus on echocardiography). There is also unlikely to be trial evidence in the foreseeable future for rarer stroke subtypes such as large artery dissection and cerebral vein thrombosis. For the latter, there is consensus among most clinicians that heparin should be used, although this is based on small trials and indirect evidence.
What to do in these less certain areas where evidence is lacking? Perhaps, fortunately, the art of medicine is not dead and decisions need to be made on an individual basis. Hence, we would generally agree with Caplan that heparin is reasonable to use in some circumstances and that further trial evidence is needed. One stark fact remains: in our own practice, we have become far more selective in the use of heparin, and this is a direct result of accumulated evidence to date. We look forward to more.
Section Editors: Geoffrey A. Donnan, MD, FRACP, and Stephen M. Davis, MD, FRACP