LAUSR

The selection of cerebral protection devices is a major daily issue for physicians performing carotid interventions. We read with great interest the paper by Omran et al. which provided an updated, articulated meta-analysis of published studies comparing proximal occlusion versus distal filter for cerebral protection during carotid stenting [1]. As discussed by the authors, published studies provided no homogeneous results and a series of subgroup analyses have been performed in the effort of finding the possible impact of various clinical and technical characteristics on meta-analysis results. Overall, such meta-analysis seems to discard the hypothesis of any possible benefit for the systematic adoption of proximal protection instead of distal filter protection [1]. Furthermore, none of the variables used to stratify the results has been found to modify significantly such negative finding [1]. Yet, the impact of device selection for proximal protection has not been extensively investigated but may potentially be relevant. Indeed, available devices are known to act differently. In particular, Flow Reversal System (W.L. Gore and Associates, Flagstaff, Arizona, USA) provides internal carotid flow reversal and requires two vascular accesses (arterial and venous), while MO.MA Ultra Proximal Cerebral Protection device (Medtronic, Santa Rosa, California, USA) provides carotid flow blockage and requires a single arterial access. Furthermore, the MO.MA device has a unique deliverability which is testified by impressively high success rates when used in unselected carotid interventions [2] and by its ability to be delivered by the transradial approach [3]. On such bases, we evaluated the possible specific benefit of MO.MA, by performing, as done by Omran et al. [1] in their study, a random-effects meta-analysis to assess the risk difference (RD) with 95% confidence intervals (CI). A total of six prospective randomized trials [4–9] on 407 patients randomized to MO.MA or distal filter protection were identified. Overall, there was numerically lower clinically detectable strokes in MO.MA-treated as compared with filter-treated patients (3 out of 210 cases vs. 8 out of 197) with no statistically significant difference between the two modalities (RD 0.02, 95% CI 20.01 to 0.06). Yet, diffusionweight magnetic resonance was commonly used in such trials and allowed to detect important physiopathologic signals. In particular, as compared with distal filter protection, MO.MA was found to significantly reduce the occurrence of any new cerebral lesion (RD 0.201, 95% CI 0.036–0.366) (Fig. 1, panel A) as well as the number of new cerebral lesions per patient (RD 0.072, 95% CI 0.012–0.131) (Fig. 1, panel B). These results may be attributable to the fact that MO.MA is conceived to allow retrieve emboli of any size during the carotid lesion guidewire crossing and stent implantation phases while emboli detached during filter placement and embolic debris smaller than filter’s porous during stenting are expected to reach the brain with distal filter protection. Of note, despite the recognized higher technical complexity of the MO.MA device, the procedure duration in such trials was not significantly different as compared with distal filter protection (P 5 0.19). Actually, the main concern regarding systematic use of stenting instead of surgery comes from the possibility of higher risk for minor cerebrovascular events. Within the limitation of the small sample size of all available trials in the field, these results looks interesting since they support the hypothesis of a possible advantage for MO.MA selection during carotid interventions in terms of minor cerebral damage. Such observations shed new light on the refinement of carotid intervention technique and call for further clinical studies adequately powered to assess the clinical impact of routine MO.MA use.