Use of a Thrombelastograph Platelet Mapping Assay for Diagnosis of Clopidogrel Resistance: A Case Report

Abstract: A 62-year-old woman presented to the emergency department with sudden collapse, intractable ventricular fibrillation, and an inferior wall myocardial infarction (MI). An emergent cardiac catheterization showed a totally occluded right coronary artery (RCA). A bare-metal stent was placed in the stenosis, resulting in thrombolysis in myocardial infarction (TIMI)-III flow with 0% residual stenosis. Four days after stenting, the patient developed chest pain. A repeat cardiac catheterization showed a totally occluded stent. The patient was subsequently tested using a thrombelastograph (TEG) Platelet Mapping assay to exclude clopidogrel resistance. The assay confirmed the patient to be non-responsive to clopidogrel for the inhibition of platelet ADP receptors. In an attempt to increase ADP inhibition, the ADP antagonist was changed to ticlopidine. Further testing was confounded by the presence of abciximab; however, the patient has remained free of cardiac events.