Balloon-Expandable Transcatheter Heart Valves and Mitral Annular Calcification

Improvements in quality of life, symptoms, and stable prosthesis function at 2-year follow-up in patients with severe mitral annular calcification (MAC), bioprosthetic mitral valve (MV) dysfunction, and failed annuloplasty ring are associated with use of balloon-expandable aortic transcatheter heart valves, according to findings published in the Journal of the American College of Cardiology.

Investigators sought to evaluate 2-year clinical outcomes after transcatheter mitral valve replacement (TMVR) among patients enrolled in the MITRAL (Mitral Implantation of Transcatheter Valves; ClinicalTrials.gov Identifier: NCT02370511) trial. The MITRAL trial assessed outcomes in mitral valve-in-valve replacement (MViV), valve-in-mitral annular calcification (ViMAC), and mitral valve-in-ring replacement (MViR). The primary endpoint of the study was mean MV gradient of 10 mm Hg or more and absence of a mitral regurgitation (MR) grade of 2+ or higher at 2 years. The secondary endpoint was all-cause death at 2 years.

The investigators initiated the multicenter prospective study at 13 US sites. Included patients had high surgical risk and severe MAC, prior failed bioprosthetic MV replacement, or prior failed mitral annuloplasty ring repair. Overall, 91 patients were enrolled from February 2015 through December 2017 (30 patients with MViV, 31 ViMAC, 30 MViR).

Patients in the MViV group had a mean age of 76±10 years, 63% were women, 10% used home oxygen, 20% had diabetes, and median left ventricular ejection fraction was 56%. Patients in the ViMAC group had a mean age of 75±8 years, 71% were women, 23% used home oxygen, 39% had diabetes, and median left ventricular ejection fraction was 63%. Patients in the MViR group had a mean age of 72±9 years, 37% were women, 13% used home oxygen, 30% had diabetes, and median left ventricular ejection fraction was 47%.

Two-year all-cause mortality was 6.7% in the MViV group, and 85% of patients were New York Heart Association (NYHA) functional class I to II. Mean MV gradient in this group was 6.9±2.4 mm Hg. Only 1 of the 2 deaths in this group was cardiovascular in etiology. Stroke occurred in 6.7% of patients at 2 years. There was no hospitalization for heart failure between years 1 and 2 of follow-up. There were no cases of endocarditis or valve thrombosis at 2 years.

All-cause mortality was 39.3% in the ViMAC group, and 66.7% of patients were NYHA functional class I to II. Mean MV gradient in this group was 5.6±2.0 mm Hg. Among deaths in this group, 6 of 11 were cardiovascular in etiology. Stroke occurred in 10.7% of patients at 2 years. There were no hospitalizations for heart failure between years 1 and 2 of follow-up. There were no cases of endocarditis and 1 case of prosthetic valve thrombosis at 2 years.

All-cause mortality was 50% in the MViR group. There were 65% of patients who were NYHA functional class I to II, and mean MV gradient in this group was 6.5±2.7 mm Hg. Among deaths in this group, 5 of 30 were cardiovascular in etiology. Stroke occurred in 3.3% of patients at 2 years. There were 27% of patients rehospitalized for heart failure at 2 years.

The investigators noted that all patients had mild mitral regurgitation at 2 years. There was sustained improvement in the Kansas City Cardiomyopathy Questionnaire scores for the survivors in all 3 arms compared with baseline.

Study limitations include the underpowered sample size and lack of randomization and use of a control group. Additionally, there may be survival bias.

“Use of balloon-expandable aortic transcatheter heart valves in selected patients with severe MAC, failed annuloplasty ring, and bioprosthetic MV dysfunction is associated with improvements in symptoms, quality of life, and stable prosthesis function at 2-year follow-up,” the investigators wrote. “The MViR group experienced higher mortality rates between 1 and 2 years compared to the MViV and ViMAC groups.”

Disclosure: This research was supported by Edwards Lifesciences. Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.