The condition, termed massive mitral annular calcification (MAC), involves significant calcium deposition on the mitral annulus. This degenerative process is generally associated with aging but may also relate to chronic kidney disease, diabetes, and hypertension. Its incidence stands at 2.8%, occurring more frequently in women. Mitral valve surgery mortality in these patients remains high, ranging from 6% to 14% in selected series and outcomes.

This retrospective study covered a mean follow-up of 21 months and examined 15 patients who underwent mitral valve replacement due to severe valvular dysfunction associated with MAC. Patients were treated between January 2016 and May 2022. During the intervention, the Cavitron® ultrasonic surgical aspirator was employed for annular decalcification, and the posterior annulus was reconstructed using a bovine pericardial patch.

The mean age of the patients was 73 ± 8 years, with an 86.7% female predominance. Indications for mitral valve surgery included degenerative mitral regurgitation in 8 patients (53.3%), mitral stenosis in 4 patients (26.7%), infective endocarditis in 2 patients (13.3%), and left ventricular rupture salvage after an attempted implant without decalcification in 1 patient (6.7%). Concomitant procedures included aortic valve replacement in 11 patients (73.3%), tricuspid annuloplasty in 9 patients (60.0%), coronary revascularization in 1 patient (6.7%), and arrhythmia surgery in 7 patients (46.7%). During surgery and the hospital stay, there were no recorded deaths or complications specifically associated with mitral annular calcification. Postoperative complications included stroke in 1 patient (6.7%), initiation of hemodialysis in 1 patient (6.7%), temporary tracheostomy in 2 patients (13.3%), and re-exploration for bleeding in 2 patients (13.3%). Medium-term follow-up showed four deaths, with two attributed to respiratory sepsis at 6 and 19 months, one due to an unknown cause at 7 months, and one due to cerebral hemorrhage at 31 months.

The authors concluded in this article that the treatment strategy employed yielded satisfactory clinical outcomes, demonstrating safety and reproducibility even in high-risk patients requiring multiple surgical procedures.

COMMENTARY:

Mitral valve surgery in patients with severe MAC is a complex procedure, not only because of the surgical technique but also due to comorbidities associated with advanced patient age. Currently, no ideal therapeutic strategy exists for managing MAC. Techniques range from calcium “mold” resections with subsequent reconstruction to conservative approaches with non-orthotopic implantation, such as intra-atrial mitral prosthesis placement. However, the latter carries risks, including aneurysmal atrial dilation and valve dehiscence.

Transcatheter techniques have been developed as options for high-surgical-risk patients, but despite a 72% periprocedural success rate, the 30-day mortality remains high at 29.7%, suggesting it may not be the optimal strategy. In prior blog entries, the role of open TAVI prosthesis implantation has also been examined as a hybrid technique for treating this condition.

The partial resection technique aims for minimal debridement to allow mitral prosthesis implantation without disrupting the annulus, with studies reporting a 78.8% survival rate at 5 years. However, this strategy is not free of complications, including risks of atrioventricular groove rupture due to suture placement through or behind residual calcification, and paravalvular leakage. Additional risks include circumflex coronary vessel injury and/or permanent complete atrioventricular block.

Although complete resection is the most aggressive approach, the authors propose a comprehensive approach to managing MAC, from preoperative planning to postoperative intensive care. Key steps include adequate mitral valve exposure through a superior transseptal incision, selective decalcification using CUSA, annular reconstruction with bovine pericardium, and implementing measures to reduce left ventricular afterload in the acute postoperative phase, including pharmacotherapy, deep sedation, and intra-aortic balloon pumping.

The main drawback of this strategy is the need for prolonged intubation, which may lead to complications such as respiratory infections, critical illness polyneuropathy, and respiratory distress syndrome. However, these complications are considered manageable given the high complexity of the procedure. The small patient cohort and short follow-up period limit the generalizability of the findings. Furthermore, only 33% of patients had complete posterior annular calcification, and 13.3% had circumferential calcification, with the remainder exhibiting calcification over less than two-thirds of the posterior annulus. In cases of mortality, the degree of MAC was not specified but did not appear related.

The technique appears safe, but its reproducibility requires availability and expert handling of the Cavitron® ultrasonic surgical aspirator (CUSA). It is advised to perform this procedure in specialized centers with dedicated mitral valve teams and intensive care units experienced in managing postoperative care for high-complexity cardiovascular surgeries.

REFERENCE:

Numaguchi R, Takaki J, Nishigawa K, Yoshinaga T, Fukui T. Outcomes of mitral valve replacement with complete annular decalcification. Asian Cardiovasc Thorac Ann. 2023 Nov;31(9):775-780. doi: 10.1177/02184923231206237.