Intravenous heparin for acute stroke: what can we learn from the megatrials?

Recently published large clinical trials of heparin and aspirin in acute stroke-the International Stroke Trial, Chinese Acute Stroke Trial, and Trial of ORG 10172 in Acute Stroke Treatment--fail to show a net benefit from heparin. None of these trials used i.v., dose-adjusted, unfractionated heparin as generally employed in the United States. However, the control groups in these trials provide data on acute stroke recurrence in large numbers of patients, and these stroke recurrence rates can be used to establish an upper limit for the potential efficacy of antithrombotic therapy. The rates of recurrent ischemic stroke in the control groups of these trials were low, ranging from 0.6 to 2.2% per week. The low rates of recurrent stroke observed in these groups, coupled with the morbidity and mortality associated with i.v. heparin in this patient population, argue against routine use of i.v. heparin in the acute stroke period.