Transseptal Transcatheter Mitral Valve Replacement for Mitral Annular Calcification: ENCIRCLE MAC Registry 1-Year...

Patients with symptomatic mitral valve dysfunction (MVD) and mitral annular calcification (MAC) represent one of the most challenging populations in structural heart disease. Advanced age, multiple comorbidities, extensive annular calcification, and unfavorable anatomy often preclude surgical mitral valve replacement or transcatheter repair, leaving many patients with limited treatment options. Whether fully percutaneous transseptal transcatheter mitral valve replacement (TMVR) can provide a meaningful treatment pathway for patients with MAC-related MVD remains uncertain.

The goal of this study was to evaluate 1-year clinical, echocardiographic, and patient-centered outcomes after transseptal TMVR with the SAPIEN M3 system in patients with symptomatic MAC-related MVD.

The ENCIRCLE (SAPIEN M3 System Transcatheter Mitral Valve Replacement Via Transseptal Access) trial MAC Registry is a prospective, multicenter, single-arm study that enrolled symptomatic patients with MAC-related MVD, including ≥ moderate to severe mitral regurgitation (MR), severe mitral stenosis, or combined moderate MR with at least moderate mitral stenosis, who were considered unsuitable for surgery or transcatheter repair. The primary endpoint was a nonhierarchical composite of all-cause mortality and heart failure hospitalization (HFH) at 1 year.

Among 364 screened patients, TVMR was attempted in 100, and the valve was implanted in 93. Mean age was 76.1 ± 9.2 years, 51.0% were male, 73.0% were in NYHA functional class III/IV, and mean Society of Thoracic Surgeons Predicted Risk of Mortality score for mitral valve replacement was 8.4% ± 4.9%. At 1 year, the Kaplan-Meier estimate of all-cause mortality or HFH was 33.6% (95% CI: 25.0%-44.1%), with 21.1% all-cause mortality and 19.4% HFH. Disabling stroke occurred in 5.1%, clinically significant left ventricular outflow tract obstruction in 4.8%, valve thrombosis in 2.3%, hemolysis requiring transfusion or mitral valve reintervention in 9.2%, and mitral valve re-intervention in 11.4%. Among implanted patients, MR ≤1+ was achieved in 98.5% at 1 year. Improvements in NYHA functional class, Kansas City Cardiomyopathy Questionnaire Overall Summary score, and 6-minute walk distance were sustained through 1 year.

In carefully selected patients with symptomatic MAC-related MVD unsuitable for surgery or transcatheter repair, transseptal TMVR with the SAPIEN M3 system was associated with sustained MR reduction and meaningful improvements in symptoms and quality of life through 1 year. These findings support consideration of transseptal TMVR as a treatment pathway for selected patients with MAC-related MVD.