Treatment of Native Calcific Mitral Stenosis using Commercially Available Transcatheter Heart Valves (THV): Results from the First German THV Mitral Stenosis Registry

Objectives: Due to an increasing life expectancy, degenerative calcific mitral stenosis is becoming more prevalent in western developed countries. Severe mitral annular calcification is surgically challenging since decalcification may lead to irreparable damage. Thus, THV implantation in mitral position might be an alternative treatment concept. However, available data are scarce.

Methods: A survey was conducted within Germany collecting cases of transcatheter mitral valve implantation for native calcific mitral stenosis from 72 centers. Out of these centers, a total of 26 cases were reported from 12 centers. Data were collected in a dedicated database. A multicenter retrospective analysis of clinical outcomes was performed.

Results: Mean age was 75.5 ± 8.9 years (male 42.3%; log EuroScore: 24.2 ± 18.6%; STS score: 9.4 ± 6.3%). In total, n = 18 balloon-expandable valves (Sapien XT: n = 7; Sapien 3: n = 11) and n = 8 mechanical expanding valves (DirectFlow: n = 6; Lotus: n = 2) were attempted for THV implantation. Access was transapical in 18 patients and transatrial in 3 patients. Furthermore, in 5 cases THV were implanted during open heart mitral valve surgery under visual guidance as a bail-out procedure. Acute procedural success was achieved in 21 patients (80%). Significant left ventricular outflow tract (LVOT) obstruction occurred in 5 patients (19.2%). Acute significant (> 2+) paravalvular leakage (PVL) was observed in 2 patients (7.6%), whereas additional 3 patients (11.5%) revealed delayed occurrence of significant PVL. Necessity of a second valve implantation (valve-in-valve) was present in 2 patients (7.6%). Acute valve embolization/migration occurred in one patient (3.8%), and delayed valve embolization/migration was observed in 2 patients (7.6%). Despite low acute procedural mortality (3.8%), delayed conversion to open heart surgery was necessary in 3 patients (11.8%). While functional data at 30 days demonstrated a significant improvement, overall in-hospital mortality was 23.1%.

Conclusion: THV implantation for treatment of native calcific mitral stenosis might be a feasible concept in patients not suitable for conventional mitral valve replacement. However, high risk of LVOT obstruction and acute or delayed PVL requiring subsequent treatment represents a serious challenge. Thus, optimization of annulus sizing methods, optimal delivery strategies and patient selection seem to be crucial for procedural and sustained success.