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Abciximab, an Fab monoclonal antibody fragment that blocks the platelet glycoprotein IIb/IIIa receptor, is increasingly used as an adjunct to coronary intervention. Little is known, however, about the efficacy and safety of readministration of abciximab. This study examined and characterized outcomes of patients receiving abciximab for a second time. From April 1995 to June 1997, 164 consecutive patients were readministered abciximab at our 3 institutions. We retrospectively examined and analyzed in-hospital outcomes in this cohort. The median time to readministration was 95 days. The angiographic success rate of percutaneous intervention was 99.5%. Rates and 95% confidence intervals of in-hospital events were death 2% (0.7% to 6.1%), myocardial infarction 3% (1% to 7%), coronary bypass surgery 0% (0% to 2.2%), and intracranial hemorrhage 2% (0.4% to 5.3%). Severe thrombocytopenia was observed in 4% of patients (1.4% to 7.8%) after readministration. Allergic or anaphylactic reactions were not observed. Major bleeding was associated with excessive concomitant antithrombotic therapy. Patients undergoing readministration of abciximab within 2 weeks of first administration experienced a higher incidence of severe thrombocytopenia (12% vs. 2%, p = 0.046). Thus, abciximab remains clinically efficacious when readministered as an adjunct to percutaneous coronary intervention. However, concomitant heparin administration must be carefully monitored and warfarin therapy should be avoided. Vigilant surveillance for thrombocytopenia should be employed. Reduced dosing may be necessary when abciximab is readministered within days of the initial administration. [ABSTRACT FROM AUTHOR]

Background: Platelets play a crucial role in the ischemic complications of percutaneous coronary procedures. The recent availability of c7E3 Fab (abciximab; ReoPro), a chimeric monoclonal antibody Fab fragment directed against the platelet glycoprotein IIb/IIIa receptor, has reduced abrupt closure and other adverse clinical events and lessened the need for revascularization procedures. As experience accrues, rare cases of acute profound thrombocytopenia have been revealed., Methods and Results: From November 1991 to July 1996, patients at Duke University Medical Center who underwent percutaneous coronary revascularization and received their first exposure to c7E3 Fab were evaluated for the development of acute profound thrombocytopenia, defined as a platelet count < 20 x 10(9)/L occurring within 24 hours of initial treatment. Four patients (0.5%) developed acute profound thrombocytopenia within 11 to 21 hours of receiving the c7E3 Fab bolus. Nadir platelet counts ranged from 1 to 16 x 10(9)/L and occurred within 11 to 26 hours. No patient developed a significant hemorrhagic complication, and each patient's platelet count responded to platelet transfusion. Platelet counts remained depressed for at least 3 days but returned to baseline within 2 weeks., Conclusions: Acute profound thrombocytopenia can occur after c7E3 Fab administration. Its development was not predictable, and it requires consideration in every patient treated. A platelet count 2 to 4 hours after the bolus would likely have detected these four cases. When indicated, platelet transfusion will raise the platelet count to safer levels without adverse effects. The differential diagnosis (including heparin-induced thrombocytopenia), a plan for management, and postulates as to the mechanism are discussed.