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Objectives: Previous studies have investigated the development of new ischemic brain lesions on diffusion-weighted MRI (DW-MRI) after carotid artery stenting (CAS) for symptomatic stenosis. The rate of ischemic brain injury after CAS for asymptomatic stenosis has not been established, but is presumed to be less likely. This study assessed the occurrence of cerebral embolization after CAS for asymptomatic vs. symptomatic carotid stenosis.
Methods: During an 18-month period, 40 patients at high risk or with contraindications for CEA underwent CAS under filter embolic protection and were prospectively evaluated. Indications for CAS included moderate (50% or greater) symptomatic carotid stenosis or severe (80% or greater) asymptomatic carotid stenosis determined with duplex ultrasound and confirmed during the procedure with digital subtraction angiography (DSA). Transcranial Doppler (TCD) during CAS and pre- and 24-hour postprocedural DW-MRI were used to assess cerebral embolization. Prior to intervention and after filter deployment, virtual histology intravascular ultrasound (VH-IVUS) images were obtained to assess plaque composition. Univariate and nonparametric analyses were used to compare differences in cerebral embolization after CAS in asymptomatic and symptomatic patients.
Results: CAS was performed for 23 (58%) asymptomatic and 17 (42%) symptomatic carotid stenoses. The median microembolic counts detected by TCD were 285 (interquartile range [IQR], 182-376) for asymptomatic and 313 (IQR, 170-426) for symptomatic carotid stenosis (P=.6). New acute cerebral emboli detected with DW-MRI occurred in 50% of asymptomatic and 50% of symptomatic patients undergoing CAS (P=.9). The ipsilateral and total median number of DW-MRI lesions between groups were not statistically significantly different, i.e. 1 (IQR, 0-2.5) and 1.5 (IQR, 0-3) vs. 0.5 (IQR, 0-2) and 0.5 (IQR, 0-3) for asymptomatic vs. symptomatic carotid stenosis, respectively (P>.5). One asymptomatic patient sustained a minor stroke after CAS, whereas no new neurologic events occurred in symptomatic patients; the 30-day stroke-death rate was 2.5% in this series.
Conclusions: Cerebral embolization, as detected by TCD and DW-MRI, occurs with similar frequency after CAS for asymptomatic and symptomatic carotid stenosis. This observational study questions the safety of CAS under embolic protection for asymptomatic carotid stenosis as new ischemic brain injury occurs in up to a half of asymptomatic patients.