A Pilot Trial of Low-Dose Intravenous Abciximab and Unfractionated Heparin for Acute Ischemic Stroke: Translating GP IIb/IIIa Receptor Inhibition to Clinical Practice.
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Thrombolysis remains a mainstay in the treatment of ischemic stroke. While not usually considered in the spectrum of clot lysis, experimental data show that inhibition of the platelet glycoprotein (GP) IIb/IIIa receptor can reduce as well as reverse thrombus formation and improve microvascular flow in stroke models. However, a recent clinical trial of GP IIb/IIIa inhibition in stroke did not demonstrate clinical benefit and was associated with increased hemorrhage. Based on an understanding of the relationship between GP IIb/IIIa receptor inhibition, efficacy and hemorrhage, we hypothesized that a lower dose of abciximab would achieve a favorable range of platelet inhibition and potentially good clinical outcomes. Forty-four patients with suspected large vessel occlusion, who were not eligible for rt-PA were offered treatment with approximately 30% lower total dose of intravenous abciximab if within 6h for anterior circulation or 24h for posterior circulation stroke (later modified to 12h). Concomitant anticoagulation, usually with unfractionated heparin was employed. The extent of platelet inhibition was measured in 21 patients. Hemorrhage rate and 90-day functional outcomes and mortality were obtained. A matching algorithm involving finding the nearest neighbor from individual subjects in the control arm of the NINDS rt-PA database was used to compare outcomes at similar baseline characteristics and gender. Mean platelet inhibition was 92.16.7% vs inhibition reported with percutaneous coronary intervention (PCI) of 9610; p=0.08. Successful matching to NINDS controls was accomplished: after outlier elimination, median and mean NIHSS of the abciximab subjects compared to NINDS controls was 16.5 vs 15.5 (p=0.92) and 16.3 vs 16.0 (p=0.86). Mean age was 67.2 vs 67.1 (p=0.97). Mean glucose was 141 vs 142 (p=0.92). There was one symptomatic hemorrhage; minor hemorrhages occurred in 9%. The percent of patients who achieved an mRS 0-2 or died in the treated vs matched NINDS control patients was 63 vs 38 (p=.02) and 23 vs 23 (p=1.0). Our pilot results indicated that a lower dose of abciximab results in platelet inhibition similar to that achieved in the coronary vascular bed during PCI. Comparison to matched historical controls suggests that this lower dose in combination therapy may be safe and effective therapy for thrombotic stroke and a randomized trial is warranted.