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AJNR - American Journal of Neuroradiology

Published ahead of print on January 25, 2008
doi: 10.3174/ajnr.A0917

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Monitoring of Clopidogrel-Related Platelet Inhibition: Correlation of Nonresponse with Clinical Outcome in Supra-Aortic Stenting

S. Müller-Schunk^a, J. Linn^a, N. Peters^b, M. Spannagl^c, M. Deisenberg^d, H. Brückmann^a and T.E. Mayer^a

^a Department of Neuroradiology, Ludwig Maximilians University, Munich, Germany
^b Department of Neurology, Ludwig Maximilians University, Munich, Germany
^c Department of Hemostaseology, Ludwig Maximilians University, Munich, Germany
^d Department of Anesthesiology, Ludwig Maximilians University, Munich, Germany

View larger version (17K): [in this window] [in a new window]   Fig 1. The fifth percentile of the results of the healthy blood donors at 52 AU is marked and used as a cutoff for nonresponsiveness in neurologic patients. Patients under clopidogrel medication show marked platelet inhibition compared with the blood donors. Neurologic patients with aggregation over 52 AU after clopidogrel medication are classified as nonresponders (also see Fig 2).

View larger version (19K): [in this window] [in a new window]   Fig 2. Fourteen (28%) of 50 patients met the criteria of nonresponse with test results of over 52 AU. Patient 1 received a second full loading dose of 300 mg of clopidogrel before treatment after the high initial test result. Patient 7 did not receive a stent due to a free-floating thrombus. The other patients marked with numbers either suffered peri-interventional clinical events (3 of 50; patients 3, 4, and 6) or adverse events during the angiographic procedure without any clinical consequences (2 of 50; patients 2 and 5). All of the patients (5 of 50) with any type of adverse event qualified as clopidogrel nonresponders as measured by the multiplate analyzer.

View larger version (134K): [in this window] [in a new window]   Fig 3. Patient 2 (see Fig 2) showed the second highest aggregation level of all of the patients. She developed progressive in stent clotting at the end of the procedure (A) that could be reversed by intravenous administration of tirofiban (B).