Flow impairment during protected carotid artery stenting: impact of filter device design.

Purpose: To investigate the impact of filter design on blood flow impairment in the internal carotid artery (ICA) among patients undergoing carotid artery stenting (CAS) using filter-type emboli protection devices (EPD). Methods: Between July 2003 and March 2007, 115 filter-protected CAS procedures were performed at an academic institution in 107 consecutive patients (78 men; mean age 68 years, range 38-87). The Angioguard, FilterWire EZ, and Spider filters were used in 68 (59%), 32 (28%), and 15 (13%) of cases, respectively. Patient characteristics, procedural and angiographic data, and outcomes were prospectively entered into an electronic database and reviewed retrospectively along with all angiograms. Results: Flow impairment while the filter was in place was observed in 25 (22%) cases. The presumptive reason of flow impairment was filter obstruction in 21 (18%) instances and flow-limiting spasm at the level of the filter in 4 (4%). In all cases, flow was restored after retrieval of the filter. Flow obstruction in the ICA occurred more frequently with Angioguard (22/68; 32.3%) than with FilterWire EZ (2/32; 6.2%) or Spider (1/15; 6.7%; p=0.004). No flow occurred in 13 (19%) procedures, all of them protected with Angioguard; no patient treated with other devices experienced this event (p=0.007). Two (8.0%) strokes occurred in procedures associated with flow impairment, while 1 (1.1%) event was observed in the presence of preserved flow throughout the intervention (p=0.11). Conclusion: Flow impairment in the ICA during filter-based CAS is common and related to the type of filter used.