Ancrod for Acute Ischemic Stroke: A New Dosing Regimen Derived from Analysis of Prior Ancrod Stroke Studies

Background: Ancrod, a fibrinogen-reducing agent, has been evaluated as treatment beginning within 3 or 6 hours of onset Of acute ischemic stroke with inconsistent results. The data sets from these studies provide an opportunity to determine whether ancrod-related variables are associated with efficacy and safety. Objective: This post hoc analysis of data from the Stroke Treatment with Ancrod Trial (STAT) analyzed ancrod-related variables as potential determinants of efficacy or safety. The resulting hypotheses were then tested in the European STAT (ESTAT) database. Methods: The relationships between ancrod-related variables and the Outcomes of efficacy and symptomatic intracranial hemorrhage (ICH) were analyzed using a 3-stage multi-variate process. Results: Good clinical outcome at 3 months based on the Barthel Index occurred almost twice as often in rapid defibrinogenators (>= 30 mg/dL/h) (52%) as in slow defibrinogenators (26%), with no increase in mortality or symptomatic ICH. Compared with a 20.7% incidence of symptomatic ICH in patients with mean post-9-hour fibrinogen levels less than or equal to 60 mg/dL, symptomatic ICH incidence was 0.8% in those with mean levels greater than 60 mg/dL (with no loss of efficacy). There were no symptomatic ICHs among 220 North American patients with mean levels greater than 70 mg/dL. It was hypothesized that an initial controlled rapid ancrod infusion with mean post-9-hour fibrinogen levels greater than 70 mg/dL would yield superior efficacy and safety. Such ESTAT patients had statistically significant efficacy versus placebo and a marked reduction in the incidence of symptomatic ICH versus patients taking ancrod with lower maintenance fibrinogen levels. Conclusion: Modifications to ancrod dosing may substantially improve efficacy while reducing the rate of symptomatic ICH.