Late cerebral embolization after emboli-protected carotid artery stenting assessed by sequential diffusion-weighted magnetic resonance imaging.

OBJECTIVES: This study sought to assess the timing of cerebral ischemia after emboli-protected carotid artery stenting (CAS).
BACKGROUND: Predominantly clinically silent cerebral ischemia has been observed in up to 50% of patients undergoing emboli-protected CAS. The timing and location of cerebral ischemia has not been sufficiently elucidated.
METHODS: In 58 patients (69.6 +/- 8.3 years) who underwent 59 procedures, diffusion-weighted magnetic resonance imaging (DWMRI) was performed before the intervention and at 2 time points (t(1) and t(2)) after the intervention.
RESULTS: No patient showed recent cerebral injury before CAS. At t(1) = 3.5 +/- 1.8 h, new ischemic foci, all located in the ipsilateral hemisphere, were observed in 12 of 59 DWMRI studies (20.3%, 95% confidence interval: 11.0% to 32.8%). At t(2) = 18.0 +/- 3.1 h, 7 more DWMRI scans showed recent ischemic foci, and 3 scans in patients with positive scans at t(1) showed additional foci, for a total of 10 scans (17.0%, 95% confidence interval: 8.4% to 29.0%) documenting late cerebral ischemia. In 4 of these (40%), ischemic foci were located contralaterally. Cerebral ischemia was not associated with overt neurological sequelae out to 30 days in any patient.
CONCLUSIONS: The incidence of late cerebral ischemia occurring between 3.5 and 18 h after emboli-protected CAS was 17%. It may occur with equal likelihood in either hemisphere. Preventive measures to possibly reduce the incidence of cerebral embolization should focus not only on the target lesion, but also on the access vasculature. Patients should be monitored and DWMRI delayed for at least 18 h after the intervention.