The incidence of microemboli to the brain is less with endarterectomy than with percutaneous revascularization with distal filters or flow reversal.

BACKGROUND

Current data suggest microembolization to the brain may result in long-term cognitive dysfunction despite the absence of immediate clinically obvious cerebrovascular events. We reviewed a series of patients treated electively with carotid endarterectomy (CEA), carotid artery stenting (CAS) with distal filters, and carotid stenting with flow reversal (FRS) monitored continuously with transcranial Doppler scan (TCD) during the procedure to detect microembolization rates.

METHODS

TCD insonation of the M1 segment of the middle cerebral artery was conducted during 42 procedures (15 CEA, 20 CAS, and 7 FRS) in 41 patients seen at an academic center. One patient had staged bilateral CEA. Ipsilateral microembolic signals (MESs) were divided into three phases: preprotection phase (until internal carotid artery [ICA] cross-shunted or clamped if no shunt was used, filter deployed, or flow reversal established), protection phase (until clamp/shunt was removed, filter removed, or antegrade flow re-established), and postprotection phase (after clamp/shunt was removed, filter removed, or antegrade flow re-established). Descriptive statistics are reported as mean ± SE for continuous variables and N (%) for categorical variables. Differences in ipsilateral emboli counts based on cerebral protection strategy were assessed using nonparametric methods.

RESULTS

TCD insonation and procedural success were obtained in 33 procedures (79%; 14 CEA, 14 CAS, and 5 FRS). Highest ipsilateral MESs were observed for CAS (319.3 ± 110.3), followed by FRS (184.2 ± 110.5), and CEA (15.3 ± 22.0). Pairwise comparisons revealed significantly higher ipsilateral MESs with both FRS and CAS when compared to CEA (P = .007 for FRS and P < .001 for CAS vs CEA, respectively), whereas the difference in MESs between FRS and CAS was not significant (P = .053). Periods of maximum embolization were postprotection phase for CEA, protection phase for CAS, and preprotection phase for FRS. Preprotection MESs were frequently observed during both CAS and FRS (20.4% and 63.3% of total MESs across all phases, respectively), and the primary difference between these two methods seemed to be related to lower MESs during the protection phase with FRS.

CONCLUSION

CEA is associated with lower rates of microembolization compared with carotid stenting. Flow reversal may represent a procedural modification with potential to reduce microembolization during carotid stenting; further investigation is warranted to determine the relationship between cerebral protection strategies and outcomes associated with carotid stenting.