Cerebral Embolic Protection in Catheter-Based Mitral Interventions: Research or Clinical Tool?

T ranscatheter MitraClip (Abbott Vascular, Santa Clara, California) implantation has emerged as the single catheter-based technique for mitral valve repair with global adoption. Worldwide, an estimated 25,000 patients have been treated with the MitraClip so far. Typically, the incidence of major stroke after surgical mitral valve repair or replacement is similar to what is seen after surgical aortic valve replacement, and varies between 1% and 5% (1–3). In the only randomized trial comparing MitraClip with mitral valve repair/ replacement, major stroke rate at 30 days was 1% after MitraClip and 2% after mitral valve surgery (4). The EVEREST (Endovascular Valve Edge-to-Edge Repair Study) 2 predominantly enrolled patients with degenerative mitral valve disease (4). In the larger European MitraClip registries, patients had more functional mitral regurgitation (MR). The clinically major stroke rate after clipping appeared to be negligible and <1%: 0.7% in 560 patients in the ACCESS EU (ACCESS-Europe A Two-Phase Observational Study of the MitraClip System in Europe) trial, and 0% in 1,064 patients in the German TRAMI (Transcatheter Mitral Valve Interventions) Registry (5,6). Important lessons were learned after a decade of controversy about stroke rates in patients undergoing surgical or catheter-based aortic valve replacement. The randomized PARTNER (Placement of Aortic Transcatheter Valve) I trial seemed to suggest that