Incidence of cerebral ischemic events after discontinuation of clopidogrel in patients with intracranial aneurysms treated with stent-assisted techniques

The optimal antiplatelet medication protocol for prevention of thrombotic complications after stent-assisted coil embolization of cerebral aneurysms is unclear. Early cessation of antiplatelet agents may be associated with an increased risk of cerebral ischemic events. In this study, the authors assess the incidence of stroke or transient ischemic attack (TIA) following discontinuation of a 6-week course of clopidogrel in patients with cerebral aneurysms treated with stent-assisted techniques.A retrospective review was conducted in all patients with cerebral aneurysms undergoing stent-assisted coil embolization or stent-in-stent flow diversion at the University of Iowa during a 24-month period. The antiplatelet protocol was 81 mg aspirin and 75 mg clopidogrel daily for 6 weeks, followed by 325 mg aspirin daily indefinitely. The incidence of stroke or TIA was determined by a retrospective review of medical records generated during a 3-month period following discontinuation of clopidogrel.A total of 154 patients underwent aneurysm treatment with stent techniques during this interval. Documentation of neurological follow-up 3 months after discontinuation of a 6-week clopidogrel treatment was available in 121 (78.6%) of 154 patients. Of these 121 patients, 114 were treated with stent-assisted coil embolization and 7 with stent-in-stent flow diversion. Six patients (5%) suffered an ischemic event after cessation of clopidogrel, with 2 events occurring within the first 2 weeks. Specifically, the rate of ischemic events was 5 (4.3%) of 114 in the "stent-coil" treatment group and 1 (14.3%) of 7 in the stent-in-stent group. Treatment had been performed in the setting of a subarachnoid hemorrhage in 1 patient. Atypical aneurysm features and technical factors predisposing to thrombotic events were found in all but one of these patients. Similarly, cardiovascular risk factors were present in 5 of the 6 patients in whom ischemic events developed after clopidogrel discontinuation.Clopidogrel discontinuation is associated with a 5% risk of ischemic events in patients treated with stent techniques. Any stroke related to clopidogrel discontinuation is avoidable, and longer treatment is therefore clearly necessary. Patients with cardiovascular risk factors, high-risk aneurysm features, and those undergoing stent-in-stent flow diversion might benefit the most from longer clopidogrel therapy.