The Ultegra rapid platelet function assay: Comparison to standard platelet function assays in patients undergoing percutaneous coronary intervention with abciximab therapy

Background: Despite the proven benefit of glycoprotein IIb/IIIa inhibitors during percutaneous coronary intervention, significant interpatient variability exists in antiplatelet response. Furthermore, a diminished degree of platelet inhibition is an independent predictor of adverse cardiac events, highlighting the need for accurate and precise monitoring of platelet function. Methods: Patients (n = 192) who underwent elective percutaneous coronary intervention at 4 centers were enrolled. The following 3 time points were studied: 1, baseline, before abciximab bolus administration; 2, during, within 1 hour of abciximab bolus administration; and 3, post, 24 hours after abciximab bolus administration or at the time of patient discharge, whichever occurred first. The following 3 assays were compared at all time points: Ultegra rapid platelet-function assay (Ultegra RPFA), conventional turbidometric platelet aggregometry, and receptor binding assay with [¹²⁵I]-abciximab. Variability in Ultegra RPFA measurements between operators was determined with performance of the assays at the point of care and in the laboratory. A sub-study of 22 patients at 1 center was performed in which the laboratory scientist performed all 3 assays in duplicate at each time point. Results: Comparison with the receptor binding assay and conventional platelet aggregometry in 120 patients showed that the Ultegra RPFA correlated with aggregometry (r = 0.89) and with the receptor binding assay (r = 0.89). There was good agreement (r = 0.80) between values obtained by intended users and those obtained by laboratory scientists. Furthermore, Ultegra RPFA values had equivalent precision to the standard assays. Conclusion: The Ultegra RPFA has equivalent accuracy and precision when compared with the 2 reference assays studied. Ultegra RPFA measurements are not operator-dependent and are not influenced by concomitant medications, hematologic parameters, or demographics.