Delayed thromboembolic events more than 30 days after self expandable intracranial stent-assisted embolization of unruptured intracranial aneurysms.

OBJECTIVE: The Enterprise stent is used for endovascular treatment of complex intracranial aneurysms. The purpose of this study was to evaluate delayed thromboembolic events (DTEs) that developed more than 30 days after Enterprise stent-assisted embolization (SAC) and its associated risk factors.

METHODS: There were 125 consecutive patients (90 women and 35 men; mean age, 56.1 years) who received endovascular treatment for 126 complex intracranial aneurysms using the Enterprise stent during December 2008 to May 2011. A DTE was defined as a symptomatic or asymptomatic ischemic stroke with positive findings on brain magnetic resonance imaging in the territory of the treated aneurysm and transient ischemic attack. Asymptomatic in-stent stenosis and occlusion were excluded.

RESULTS: During a mean follow-up of 32.4 months, DTEs occurred in 10 patients (7.93%). DTEs occurred on antiplatelet therapy (dual medication, n = 2, 2 months after embolization; single medication, n = 6, 10-20 months after SAC) or after discontinuation of antiplatelet therapy (n = 2, 14 months after embolization). Multivariate analysis showed that current smoking (p = 0.005) and maximum parent artery diameter >4.5mm (p = 0.003) were associated with DTE.

CONCLUSIONS: SAC with the Enterprise stent poses a considerable risk of DTE. Our results suggest that a longer duration of antiplatelet therapy and clinical follow-up may be warranted for cases with suggested risk factors. The protocol for antiplatelet therapy after SAC should be determined in a large prospective trial.