NEW YORK (Reuters Health) – Microembolic signals are detected less frequently during carotid artery stenting when a proximal occlusion device is used rather than a distal filter, an Italian team has shown.

“Proximal endovascular occlusion may provide better brain protection,” conclude the authors of the report in the October 11 issue of the Journal of the American College of Cardiology.

Dr. Piero Montorsi, with the University of Milan, and colleagues note that cerebral protection with vascular filters during carotid artery stenting (CAS) only partially prevents embolic complications. Proximal occlusion is an alternative approach and may be particularly valuable in dealing with carotid plaque with a high lipid content that has a high risk of embolization.

They compared the two approaches in 53 patients with high-risk plaques in the internal carotid artery undergoing CAS. The patients were randomly assigned to distal protection with a filter (FilterWire EZ) or proximal protection with the MO.MA system (Invatec).

The Invatec website explains that the MO.MA system is a dual balloon catheter, one of which is used to block retrograde blood flow from the external carotid artery and the other to occlude flow from the common carotid artery, thus suspending blood flow through the lesion site during stenting. Any embolic debris generated is then aspirated when the procedure is completed.

The researchers used transcranial Doppler to record microembolic signals during all phases of the stenting process, and found that mean signal counts were significantly fewer with proximal occlusion than distal filtering during lesion wiring (2 vs 18), stent crossing (0 vs 23), stent deployment (0 vs 30), and stent dilation (0 vs 16). Counts were higher during retrieval of the occlusion device than the filter (8.5 vs 2).

The mean total microembolic signal counts were 16 with the MO.MA device and 93 with the FilterWire EZ, the report indicates.

MRI studies were performed in 35 of the patients. These showed new embolic lesions after CAS in 2 of 14 patients in the MO.MA group (14.3%) and 9 of 21 in the filter group (42.8%), but the difference was not statistically significant (p=0.14), Dr. Montorsi and colleagues report.

The note that their study used microembolic signals detected by transcranial Doppler as a surrogate for cerebral embolization. In discussing the clinical implications of their findings, they point out that cerebral microemboli have been associated with cognitive decline, and that several risk factors may increase brain susceptibility to injury from microemboli. “If this holds true,” they conclude, “microembolic signal reduction during CAS should be pursued to improve clinical outcome.”

J Am Coll Cardiol 2011;58:1656–1663.