Association between Postprocedural Infarction and Antiplatelet Drug Resistance after Coiling for Unruptured Intracranial Aneurysms

BACKGROUND AND PURPOSE:Procedure-related thromboembolism is a major limitation of coil embolization, but the relationship between thromboembolic infarction and antiplatelet resistance is poorly understood. The purpose of this study was to verify the association between immediate postprocedural thromboembolic infarction and antiplatelet drug resistance after endovascular coil embolization for unruptured intracranial aneurysm.MATERIALS AND METHODS:This study included 338 aneurysms between October 2012 and March 2015. All patients underwent postprocedural MR imaging within 48 hours after endovascular coil embolization. Antiplatelet drug resistance was checked a day before the procedure by using the VerifyNow system. Abnormal antiplatelet response was defined as >550 aspirin response units and >240 P2Y12 receptor reaction units. In addition, we explored the optimal cutoff values of aspirin response units and P2Y12 receptor reaction units. The primary outcome was radiologic infarction based on postprocedural MR imaging.RESULTS:Among 338 unruptured intracranial aneurysms, 134 (39.6%) showed diffusion-positive lesions on postprocedural MR imaging, and 32 (9.5%) and 105 (31.1%) had abnormal aspirin response unit and P2Y12 receptor reaction unit values, respectively. Radiologic infarction was associated with advanced age (65 years and older, P = .024) only with defined abnormal antiplatelet response (aspirin response units ≥ 550, P2Y12 receptor reaction units ≥ 240). P2Y12 receptor reaction unit values in the top 10th percentile (>294) were associated with radiologic infarction (P = .003). With this cutoff value, age (adjusted odds ratio, 2.29; 95% confidence interval, 1.28–4.08), P2Y12 receptor reaction units (>294; OR, 3.43; 95% CI, 1.53–7.71), and hyperlipidemia (OR, 2.05; 95% CI, 1.04–4.02) were associated with radiologic infarction in multivariate analysis.CONCLUSIONS:Radiologic infarction after coiling for unruptured aneurysm was closely associated with age. Only very high P2Y12 receptor reaction unit values (>294) predicted postprocedural infarction. Further controlled studies are needed to determine the precise cutoff values, which could provide information regarding the optimal antiplatelet regimen for aneurysm coiling.

Endovascular coil embolization is a well-established treatment method for intracranial aneurysms. Recent evidence suggests that this procedure can be considered a first-line treatment for both ruptured and unruptured intracranial aneurysms.^1,2 However, endovascular coil embolization still has major drawbacks, including procedural rupture, thromboembolic complications, and durability issues. Among these shortcomings, thromboembolism is the most common problem.^3–5 To reduce thromboembolic complications, many studies investigated the association between thromboembolism and aneurysm and/or patient factors.^5–8 Previous studies have demonstrated that 30%–60% of endovascular coil embolizations for unruptured aneurysms show ischemic lesions on postprocedural diffusion-weighted images. Although most of the lesions seem to be benign, some could result in permanent neurologic sequelae. Recent studies demonstrated that antiplatelet resistance was associated with ischemic complications after coil embolization and that drug adjustment could lower the risk.^9,10 Still, these results are controversial, and the association between antiplatelet drug resistance and diffusion lesions has not yet been fully elucidated.^11,12Therefore, the purpose of this study was to verify the association between thromboembolic infarction and antiplatelet drug resistance after endovascular coil embolization for unruptured intracranial aneurysms. We also explored other risk factors for thromboembolic complications.