Breaking Barriers of Mitral Annular Calcification: A Single-Center Experience with Open Atrial Transcatheter Mitral Valve Replacement in High-Risk Patients

D. Ramini¹, H. Fang², R. Bai³, Y. Liao^2
1University of Arizona, Tucson, Arizona ²Banner - University Medical Center Phoenix, Phoenix, Arizona ³Banner University Medical Center Phoenix, University of Arizona College of Medicine-Phoenix, Phoenix, Arizona

Purpose: Patients with severe MAC are deemed too high risk to undergo traditional surgical MVR due to risk of atrioventricular groove rupture and might not qualify for percutaneous trans-septal or trans-apical MVR. In such patients, open transcatheter strategies may be more suitable, but contemporary outcomes in large series are lacking.

Methods: We conducted a single-center retrospective analysis on 36 patients with severe circumferential mitral annular calcification who underwent on-pump open atrial transcatheter mitral valve replacement between 2018 and 2023. Inclusion criteria was individuals who had been previously declined transeptal or transapical transcatheter mitral valve replacement based on the pattern of mitral annular calcification on cardiac computed tomography, risk of valve migration and neo-left ventricular outflow measurements. Logistic regression was used to identify risk factors for in-hospital mortality.

Results: Prior to surgery, 41.7% of all patients were on oral anticoagulation, while 19.4% were on immunosuppressants. Among all patients, 19% had a previous sternotomy. All patients had a preserved EF > 50% going into the operation. The majority of patients (97%) underwent the implantation of the Sapien 3 Edwards 29mm valve. During the operation, 58.3% of patients underwent a concomitant cardiac operation which included CABG 22%, AVR 20%, septal myomectomy 8.3%, TVR 6%, and ascending aortic repair 6%. Two patients had porcelain aorta and subsequently had the valve replacement under fibrillatory arrest. Trans-mitral valve gradient decreased from 8.6 pre-operatively to 2.3 postoperatively. The incidence of trace to mild paravalvular leak on intraoperative TEE was observed in 44.4% of patients, but only one patient required a procedural intervention. Among patients who survived to discharge, 92% were successfully extubated within 24 hours after the surgery, 11.6% required a permanent pacemaker upon discharge Median length of stay was 8 days. Failure to extubate within 24 hours of surgery was associated with increased in-hospital mortality (p=0.004). The overall survival rate at discharge was 72.2% while 1-year survival was 61.1%. Of patients who survived to discharge, 84.6% remained alive at the one-year mark.

Conclusion: Severe mitral annular calcification is a challenging disease with substantial risks of morbidity and mortality. Symptomatic patients are frequently considered too high-risk and consequently denied any intervention. However, open transcatheter mitral valve replacement emerges as a promising solution for these patients. Our manuscript presents the largest case series reported on this topic to date.

Identify the source of the funding for this research project: None