Immediate and long-term outcomes of ischemic versus non-ischemic functional mitral regurgitation in patients treated with MitraClip: insights from the 2011-12 Pilot European Sentinel Registry of Percutaneous Edge-to-Edge Mitral Valve Repair

BACKGROUND Outcome data comparing ischemic functional mitral regurgitation (I-FMR) versus non-ischemic FMR (NI-FMR) following percutaneous repair are not currently available in the literature. We aimed to describe the early and 12-month results following MitraClip device implantation regarding the two etiologies. METHODS Between January 2011 December 2012 the Transcatheter Valve Treatment Sentinel Pilot Registry included 452 patients with FMR who underwent MitraClip procedure in 25 centers of 8 European countries. RESULTS The prevalent etiology was I-FMR (235 patients, 52.0%). I-FMR group had a significant higher proportion of men (74.9 vs 59.9%, p<0.001) and surgical risk (logistic EuroScore 24.818.2 vs 18.816.3, p<0.001). Acute procedural success was high (95.8%) and similar between groups (p¼0.48). Patients with I-FMR required a higher, albeit not significant, number of clips to reduce MR (p¼0.08). In-hospital mortality was low (2.0%) without significant differences between etiologies. Both I-FMR and NI-FMR showed a significant post-clip improvement in NYHA functional class with the majority of patients exhibiting a NYHA class<II (82.6 and 74.2%, respectively). EuroSCORE, an impaired ejection fraction (i.e.<30%), pre-procedural chronic kidney disease and the inability to reduce themitral regurgitation represented the most important factors affecting both survival and re-hospitalization in FMR patients. Estimated overall 1-year mortality and re-hospitalization rates were 15.0 and 25.8% respectively, However, even though no significant differences in terms of long-term outcomes were demonstrated, the survival curve showed a trend toward a gradual decline in the I-FMR group versus a stabilization in the NI-FMR group after 6 months. Paired echocardiographic data, available for 264 consecutive patients, showed a persistent improvement of MR at 1 year in bothI-FMR and NI-FMR (6.6 and 5.4% of the patients with severe MR, respectively). Despite a significant overall reverse atrial remodeling after clip, suggestive for an effective correction of the volume overload, no significate changes in left ventricular volumes have been demonstrated. However, although both etiologies, showed a significant acute decrease in pulmonary pressure, only the I-FMR group demonstrated a concomitant significant acute decrement in atrial volume (DLAV 13.6ml, p¼0.016), while at the 1-year follow-up a significate reduction was detected in both groups. CONCLUSIONS This independent large cohort showed that percutaneous “edge-to-edge” therapy is associated with early and long-term improvement of MR severity and functional status both in I-FMR and NI-FMR groups. However some, albeit not significant, differences detectable both in the echocardiographic patterns and long-term outcomes, suggest the possibility that the benefit of Mitraclip differ depending on the etiologies of mitral regurgitation prompting the need for further large controlled studies investigating the underlying pathogenetic mechanisms of FMR