Thromboembolic complications in patients with clopidogrel resistance after coil embolization for unruptured intracranial aneurysms.

BACKGROUND AND PURPOSE Antiplatelet resistance is known to be associated with symptomatic ischemic complication after endovascular coil embolization. The purpose of our study was to evaluate the relationship between antiplatelet resistance and clinically silent thromboembolic complications using DWI in patients who underwent coil embolization for unruptured intracranial aneurysm. MATERIALS AND METHODS Between October 2011 and May 2013, 58 patients with 62 unruptured aneurysms who were measured for antiplatelet response using VerifyNow assay and underwent elective coil embolization for an unruptured aneurysm with posttreatment DWI were enrolled. Diffusion-positive lesions were classified into 3 groups according to the number of lesions (n=0 [grade 0], n<6 [grade I], and n≥6 [grade II]). The relationship between antiplatelet resistance and diffusion-positive lesions was analyzed. RESULTS Sixty-two endovascular coiling procedures were performed on 58 patients. Clopidogrel resistance was revealed in 23 patients (39.7%) and diffusion-positive lesions were demonstrated in 28 patients (48.3%); these consisted of 19 (32.8%) grade I and 9 (15.5%) grade II lesions. Clopidogrel resistance was not relevant to the development of any diffusion-positive lesion (grade I and II, P=.789) but was associated with the development of multiple diffusion-positive lesions (grade II, P=.002). In the logistic regression prediction model, clopidogrel resistance showed significant correlation with the development of grade II lesions (P=.001). CONCLUSIONS Multiple diffusion-positive lesions (≥6 in number) occurred more frequently in patients with clopidogrel resistance after endovascular coiling for unruptured aneurysms.