In the article, they note that randomized studies comparing CAS with carotid endarterectomy (CEA) found lower periprocedural stroke rates with CEA. But filter protection devices were used in the CAS procedures in these studies.
It’s possible, they say, that the results might have been different had proximal balloon occlusion devices been used. A proximal protection system may be more effective in preventing cerebral embolization, mainly because it is placed and functioning before the lesion is crossed and stented, and it induces reversed blood flow by occluding both the external carotid artery and the common carotid artery, they explain.
In the PROFI Study, 62 consecutive patients undergoing CAS with cerebral embolic protection for internal carotid artery stenosis were randomly allocated to proximal balloon occlusion (n=31) or filter protection (n=31). The patients had a mean age of 71.7 years and most were men (76%).
The researchers found that the incidence of new cerebral ischemic lesions on diffusion-weighted magnetic resonance imaging (the primary outcome) was significantly higher in the filter group compared with the balloon occlusion group (87.1% vs 45.2%; p=0.001).
In this study, note the researchers, proximal balloon occlusion reduced the incidence of new cerebral ischemic lesions by a factor of 1.9. Whether this translates to a lower stroke rate remains to be seen.
The number of lesions per patient was also significantly higher in the filter group compared with the balloon occlusion group (3.6 vs 1.0; p=0.0001); so too was the volume of lesions (0.59 vs 0.16 cm3; p=0.0001).
The rate of major adverse cardiovascular and cerebral events (MACCE) at 30 days was 3.2% in the filter group (1 patient had a minor stroke, NIHSS=1) and 0% in the balloon occlusion group; the difference was not significant.
There were no bleeding or vascular complications in any patient. One patient in the filter group crossed over to the balloon group because of difficulty in placing the filter and one patient in the balloon group crossed over to the filter group due to trouble advancing the stiff wire into the external carotid artery.
Based on their registry data, Dr. Bijuklic and colleagues say 83% of patients who are candidates for CAS are suitable for proximal balloon occlusion.
And compared with balloon occlusion, filters have some disadvantages; they have to cross the lesion before the protection is installed, allow small particles to pass through them, or if not well adapted to the vessel wall, to pass along the filter. Filters can also become overloaded with debris, which could spill out during retrieval. Occasionally, they can be difficult to retrieve.