Clopidogrel Resistance in Neurovascular Stenting: Correlations between Light Transmission Aggregometry, VerifyNow, and the Multiplate.
OBJECTIVE
Clopidogrel resistance is blamed for thromboembolic complications in neurovascular stent placement. Platelet-function assays are weakly standardized. The aim of this study was to correlate the results of 3 different platelet-inhibition measurements (from light transmission aggregometry, the VerifyNow P2Y12 test, and the Multiplate analyzer) and their relation to periprocedural thromboembolic complications in elective neurovascular stent placement.


METHODS
Clopidogrel resistance was determined on the day of the intervention according to predefined platelet reactivity cutoff values. All 3 tests were performed in 103 consecutive neurovascular stent-placement procedures in 97 patients (extracranial, n = 77; intracranial, n = 26).


RESULTS
The clopidogrel resistance rates were 47.6% (light transmission aggregometry), 50.5% (VerifyNow), and 35.9% (Multiplate). In 67% of the patients, clopidogrel resistance was present according to at least one method. The correlations of qualitative results that classified a patient as responsive or resistant to clopidogrel were 67.9% for light transmission aggregometry with VerifyNow, 77.7% for light transmission aggregometry with the Multiplate, and 66% for VerifyNow with the Multiplate. Periprocedural thromboembolic complications (n = 9) occurred more frequently in patients who were determined by all 3 methods to be clopidogrel resistant. The difference was most pronounced with light transmission aggregometry (complication rates, 14.4% [clopidogrel-resistant patients] vs 3.7% [clopidogrel-responsive patients]). Sensitivity and specificity rates of clopidogrel resistance in relation to embolic complications were, respectively, 78% and 55% for light transmission aggregometry, 67% and 51% for VerifyNow, and 44% and 67% for the Multiplate.


CONCLUSIONS
Clopidogrel resistance is a frequent finding in patients who undergo neurovascular stent placement. The correlations among the different testing methods are only modest and differ considerably. Light transmission aggregometry results seem to correlate with thromboembolic complications more accurately than with VerifyNow and Multiplate point-of-care methods.
From the Departments of Neuroradiology (N.F., F.K., B.E.).
N
N
Flechtenmacher
From the Departments of Neuroradiology (N.F., F.K., B.E.).
F
F
Kämmerer
Department of Laboratory Medicine (R.D., U.B.), Medilys Laboratory Company, Hamburg, Germany.
R
R
Dittmer
Department of Laboratory Medicine (R.D., U.B.), Medilys Laboratory Company, Hamburg, Germany.
U
U
Budde
Neurology (P.M., J.R.), Asklepios Klinik Altona, Hamburg, Germany.
P
P
Michels
Neurology (P.M., J.R.), Asklepios Klinik Altona, Hamburg, Germany.
J
J
Röther
From the Departments of Neuroradiology (N.F., F.K., B.E.) b.eckert@asklpios.com.
B
B
Eckert
D000368:Aged; D002545:Brain Ischemia / Q000628:therapy*; D000077144:Clopidogrel; D004351:Drug Resistance; D004621:Embolization, Therapeutic; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000628:therapy*; D020766:Intracranial Embolism / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000009:adverse effects* / Q000627:therapeutic use*; D010979:Platelet Function Tests / Q000295:instrumentation* / Q000379:methods*; D019095:Point-of-Care Systems; D013223:Statistics as Topic; D015607:Stents; D013988:Ticlopidine / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use
D010975:Platelet Aggregation Inhibitors; D000077144:Clopidogrel; D013988:Ticlopidine