Antithrombin-III Activity and the Efficacy of Heparin in Progressing Ischemic Stroke

Heparin is often used in progressing ischemic stroke. However, a substantial part of the patients continue to progress while on treatment. The purpose of this study was to evaluate if antithrombin (AT) III activity before treatment could predict patients at risk for continued progression or if heparin-induced reduction in AT-III activity during treatment is related to continued progression. The study included 42 acute stroke patients with heaprin treatment for progression of isch emic stroke. The patients were continuously supervised for progression. Intravenous heparin therapy was started as soon as possible after the progression was noticed. Antithrombin-III activity was assessed before initiation of treatment and daily during the treatment period. Nine (21 %) of the 42 patients continued to progress while on treatment. There was no statis tically significant difference in AT III activity before treatment between patients who continued to progress and those where the progression ceased when treatment was initiated. Nor were there any differences in the mean AT III activity levels during treatment for patients with more or less favorable clinical course. The individual changes (Δ AT III) were similar in both patient groups as was the proportion of patients with their low est AT III activity in the thrombogenic range (continued: 22% vs. ceased: 27%). No clinically relevant influence of AT III activity on heparin efficacy in progressing ischemic stroke was found. Key Words: Stroke progression—Heparin treatment— Antithrombin activity.