Article Figures & Data
Figures
- 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).
- 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.
- 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).
Tables
Clinical data Number (N = 50) (%) Stroke 31 62% TIA 19 38% Location of stenosis Intracranial (n) Extracranial (n) ICA 2 31 VA 2 3 BA 12 0 Total 16 (32%) 36 (68) Clopidogrel loading [h] pre-intervention Mean 47 ± 88 Minimum/maximum 6† (min) 408* (max) Note:—TIA indicates transient ischemic attack; ICA, internal carotid artery; VA, vertebral artery; BA, basilar artery.
* The exact date of the beginning of the clopidogrel medication could not be determined in 2 patients, but was more than 14 days.
† One patient (No. 1) was loaded twice, 12 and 6 hours before the stenting.
- Table 2:
Demographic data, medication, and aggregation of control subjects and neurologic patients
Variable Healthy Blood Donors Neurologic Patients Age, mean ± SD, y 41 ± 18 65 ± 8 Male, n (%) 30 (60) 36 (72) Female, n (%) 20 (40) 14 (28) Clopidogrel, n (%) 0 0 ASA + clopidogrel, n (%) 0 50 (100) Mean aggregation, mean ± SD, AU 86 ± 23 34 ± 26 5th to 95th percentile 52–137* 1–84 Total, n 50 50 Note:—ASA indicates aspirin; AU, arbitrary aggregation unit.
* The fifth percentile of the aggregation results of the healthy blood donors at 52 AU was selected as a cutoff for nonresponse in patients under clopidogrel medication.
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