Key result
An impedance value of ≥ 6 Ω on whole blood aggregometry identified clopidogrel nonresponders at risk for thromboembolic complications with 84.6% sensitivity and 70.0% specificity (AUC 0.77).
Why the study?
Dual antiplatelet therapy is required during intracranial aneurysm treatment with the Pipeline embolization device, but optimal impedance values for pretreatment whole blood aggregometry have not been defined.
Does an impedance value of ≥ 6 Ω on whole blood aggregometry predict thromboembolic complications in patients undergoing Pipeline embolization device treatment for intracranial aneurysms?
Cohort (n=49)
Does an impedance value of ≥ 6 Ω on whole blood aggregometry predict thromboembolic complications in patients undergoing Pipeline embolization device treatment for intracranial aneurysms?
Pretreatment whole blood aggregometry can identify clopidogrel nonresponders (impedance ≥ 6 Ω), who are at higher risk for thromboembolic complications following Pipeline embolization device placement.
May support pretreatment risk stratification before Pipeline embolization; hypothesis-generating pending prospective validation.
OBJECTIVE: Dual antiplatelet therapy is required for the treatment of intracranial aneurysms with the Pipeline embolization device (PED). Platelet function testing (PFT) is often used to assess the efficacy of the antiplatelet regimen prior to PED placement. The optimal impedance values for whole blood aggregometry in this setting have not been defined. METHODS: A retrospective review of a prospectively maintained database was performed for the years 2011-2015 to identify patients with intracranial aneurysms treated with the PED who underwent pretreatment PFT using whole blood aggregometry. Antiplatelet therapy was not altered based on PFT results; all patients remained on standard doses of aspirin and clopidogrel. Clinical, radiographic, and laboratory data were analyzed to identify the optimal cutoff impedance value for clopidogrel responsiveness using the receiver operating characteristic curve and Youden's index. RESULTS: Forty-nine patients underwent 53 endovascular procedures for the treatment of 76 aneurysms using the PED. The majority of these aneurysms were located in the anterior circulation (90.8%) and affected the internal carotid artery (89.5%). Patients in 30 procedures (56.6%) were identified as clopidogrel responders based on the manufacturer cutoff value (< 6 Ω). Thromboembolic complications occurred in 13 (24.5%) procedures; patients in 6 (11.3%) cases were symptomatic and those in 3 (5.7%) cases had ischemic strokes. Eleven of the 13 (84.6%) thromboembolic complications occurred in clopidogrel nonresponders. An impedance value of ≥ 6 Ω was independently associated with thromboembolic complications. The optimal electrical impedance value was identified as ≥ 6 Ω (sensitivity 84.6%, specificity 70.0%, area under the curve 0.77) for identifying clopidogrel nonresponders. CONCLUSIONS: Thromboembolic complications are more common following PED placement in patients who do not respond adequately to clopidogrel. Clopidogrel nonresponders can be identified using pretreatment whole blood aggregometry. The optimal cutoff value to categorize a patient as a clopidogrel nonresponder when using whole blood aggregometry is ≥ 6 Ω.
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Foreman et al. (2019) conducted a cohort in Intracranial aneurysms (n=49). Clopidogrel nonresponse (impedance ≥ 6 Ω) vs. Clopidogrel response (impedance < 6 Ω) was evaluated on Thromboembolic complications. An impedance value of ≥ 6 Ω on whole blood aggregometry identified clopidogrel nonresponders at risk for thromboembolic complications with 84.6% sensitivity and 70.0% specificity (AUC 0.77).
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