Platelet Testing is Associated with Worse Clinical Outcomes for Patients Treated with the Pipeline Embolization Device

BACKGROUND AND PURPOSE:The necessity for platelet-inhibition testing before aneurysm treatment in patients premedicated with antiplatelet agents is controversial. Using the International Retrospective Study of Pipeline Embolization Device registry, we studied complication rates in groups of patients who underwent platelet testing and those who did not undergo platelet testing to determine if these test results were associated with improved outcomes.MATERIALS AND METHODS:Patients in the International Retrospective Study of Pipeline Embolization Device registry with an unruptured aneurysm were categorized as those who underwent platelet testing before Pipeline embolization device treatment or those who did not. Complication rates were compared by using the Fisher exact or Pearson χ² test. Multivariate analysis was performed to determine if platelet function testing was independently associated with poor outcomes after adjusting for age, number of devices and aneurysms, aneurysm location and size, and practitioner and center volume.RESULTS:Compared with the patients who received a Pipeline embolization device without platelet testing, those who underwent platelet testing and Pipeline embolization device placement experienced higher rates of intracranial hemorrhage (0 of 187 0.0%] vs 12 of 511 2.3%], respectively; P = .04), neurologic morbidity (4 of 187 2.1%] vs 42 of 511 8.2%], respectively; P < .01), and combined neurologic morbidity and mortality (6 of 187 3.2%] vs 45 of 511 8.8%], respectively; P = .01). More patients in the platelet testing and Pipeline embolization device group were treated with multiple devices (227 38.0%] vs 56 27.8] patients, respectively; P = .01). On multivariate analysis, the group of patients who underwent platelet testing and Pipeline embolization device placement had higher odds of neurologic morbidity (OR, 3.25 95% CI, 1.10–9.61]; P = .03).CONCLUSIONS:Platelet testing in patients who undergo Pipeline embolization device placement is associated with higher rates of morbidity. Additional prospective studies are needed to determine if and when platelet testing in these patients is appropriate.

The Pipeline embolization device (PED; Covidien, Irvine, California) is increasingly used in the treatment of intracranial aneurysms.^1–4 The PED flow diverter is a bare-metal construct that serves as a scaffold for neointimal proliferation.^5,6 Because of the thrombogenic nature of the bare-metal component of the device, dual-antiplatelet therapy is required in both the preoperative and postoperative settings, and patients are required to take dual-antiplatelet therapy for several months after the procedure.In addition to aspirin, clopidogrel is currently the most commonly prescribed antiplatelet drug for dual-antiplatelet therapy among patients who undergo PED placement. However, there exists wide variability in the activation of clopidogrel among individual patients.⁷ As a result, platelet function testing is widely used among neurointerventionists to ensure proper function of the drug.^8,9 However, controversy exists as to whether platelet testing is necessary in patients who undergo PED placement, because the benefits have yet to be proved.¹⁰ By using the International Retrospective Study of Pipeline Embolization Device (IntrePED) registry,¹¹ we compared the clinical outcomes of patients who underwent platelet testing and those who did not to determine whether this testing was associated with better outcomes among patients who undergo PED placement.