Insights from the American Association for Thoracic Surgery 2025 expert consensus document on the surgical management of mitral annular calcification

Introduction

Mitral annular calcification (MAC) is a complex anatomical and physiologic entity that presents significant technical challenges in mitral valve (MV) surgery and is associated with increased periprocedural risks that are not captured by currently utilized surgical risk models. With the current global increase in the elderly population, there has been a surge of patients presenting with MAC needing MV intervention (1). Despite this growing need there remains no consensus on what the optimal surgical or interventional management strategies should be nor is there a clear understanding of how to properly risk assess these patients. To fill this gap in knowledge the American Association for Thoracic Surgery (AATS) published an expert consensus document (ECD) in 2025 providing recommendations for patients with MV disease and MAC (2). These guidelines provide a practical guide to the general cardiac surgical, interventional, and cardiology communities to aid in risk stratification, identification of indications for intervention, optimal surgical or interventional approaches, and bailout strategies in the event of complications. This document now aims to consolidate the surgical recommendations from the ECD that have evolved over the past few decades with incorporation of novel transcatheter and hybrid procedures. We place an emphasis on (I) preoperative evaluation and patient selection, (II) standard surgical techniques in MAC, and (III) hybrid procedures in MAC.

Preoperative evaluation, patient selection, and indications for intervention

A thorough periprocedural evaluation is critical for all patients presenting with MAC being considered for MV intervention. Advanced cardiac imaging with multidetector computer tomography (MDCT) is considered essential for appropriate MAC assessment and is utilized to characterize MAC severity and anatomy while three-dimensional (3D) transesophageal echocardiography (TEE) is an important component in surgical planning. The guidelines introduced a simplified classification system to grade MAC focused on the main determinants of feasibility for standard surgical valve repair and replacement: the degree of circumferential extension, calcium bar thickness, and involvement of the leaflets, trigones, and subvalvular apparatus (Table 1). This is in contrast to more complex classifications used primarily for transcatheter interventions. Invasive hemodynamic assessment with right heart catheterization (RHC) allows one to understand underlying cardiac dysfunction and degree of hemodynamic decompensation. This can guide preoperative medical optimization, exclude alternative diagnoses, and may be useful for prognostication and risk assessment.

All cases of moderate and severe MAC in high-risk patients should be evaluated by a multispecialty heart valve team that includes (though is not limited to) a cardiac surgeon and a structural heart cardiologist with expertise in MAC surgery/interventions. Assessment of interventional or surgical risks in patients with MAC is a complex process as it requires consideration of the anatomic severity of MAC, the extent of vascular calcifications, and other extra-cardiac comorbidities common in MAC patients. Hence, risk assessment should involve a multidisciplinary team that determines the feasibility of standard surgery versus hybrid or transcatheter procedures and overall operative candidacy. Just as important as identifying appropriate surgical candidates, an experienced multidisciplinary team must also be able to exclude patients with prohibitive risk profiles such as those with a limited life expectancy attributable to noncardiac comorbidities, marked frailty or poor functional capacity, and individuals who are unlikely to see symptomatic benefit and in whom MV intervention would be considered futile.

Standard surgical techniques

Once a patient is deemed a surgical candidate, the operative approach is driven largely by patient anatomy, quality of tissue, extracardiac comorbidities and surgeon experience. Two primary schools of thought have developed in dealing with annular calcification: the “resect” strategy with en-bloc decalcification and the “respect” strategy with no or limited debulking of the calcium bar (Table 2). In the resect strategy, the goal is to eliminate all calcium to restore as much pliable annulus as possible to allow healing of the prosthesis and provide durability of the repair or replacement. However, this may require reconstruction of the atrioventricular groove (AVG) and its attendant risks. In the respect strategy, none or limited removal of calcium to allow for suture placement minimizes this risk of AVG disruption. This more conservative method comes at the expense of increased risk of paravalvular leak (PVL) and/or patient prothesis mismatch (PPM) due to the inability to place an appropriately sized prothesis. The choice of approach depends on the severity of MAC, quality of the endomyocardial tissue, surgical expertise, and the overall patient risk profile. The more aggressive resect strategy may be favored in those with limited MAC and healthier tissue while the respect approach may be best suited for those higher risk patients with ventricular extension of calcium and poor tissue quality, particularly in elderly MAC patients. We have recently published our experience utilizing a limited approach to resection in dealing with high-risk patients to minimize perioperative mortality and morbidity (3).

The AATS ECD has also included a special recommendation for the use of ultrasound in MAC surgery with a class IIb recommendation, stating: “Ultrasonic debridement may be a useful adjunctive tool in surgical valve repair or replacement in patients with MAC to facilitate suture placement and seating of the prosthesis (IIb, C-LD)”. Ultrasonic debridement emulsifies and aspirates calcified matter to achieve controlled remodeling of the calcium bar for safe suture placement and prothesis insertion without the need for more extensive decalcification. The fine-tuned control of the ultrasonic device could potentially decrease the risk of AVG disruption (4).

With regards to the repairability of the MV in MAC, similar principles as in non-MAC cases can be applied. When leaflet tissue is pliable, has limited calcification confined to a resectable segment, and excess tissue is present, repair should be considered. Data support the survival benefit of repair even in MAC, albeit when done with good durability (5,6). However, it should be emphasized that replacement is preferred over a non-durable repair—particularly in cases where there is extensive MAC, where the calcium bar is infected, or where stenosis is the primary pathology. When replacement is pursued, the degree of calcification can make annular suture placement and proper valve seating challenging. A felt strip layer can be used to buttress the sewing cuff to minimize PVL and chordal sparing techniques should be used to preserve ventricular-annular continuity, minimizing the risk of midventricular tears, a type of AVG disruption.

In cases of deep extension of calcium onto the aorto-mitral curtain, such as in radiation-induced MAC, the surgeon should be prepared to undergo concomitant aortic valve and/or root replacement with reconstruction of the intervalvular fibrosa—the so called “Commando” procedure. The likelihood that this may be necessary should be identified during preoperative computed tomography (CT) imaging. The anticipated need for such procedures should prompt referral to a comprehensive valve reference center with expertise in these complex operations.

Hybrid procedures

In the most challenging anatomy, conventional MV replacement may not be possible due to the degree of calcific involvement and the inability to place annular sutures. Historically, these patients would either be considered inoperable or be taken to the operating room for planned extreme risk surgery where, only after conventional attempts at mitral replacement had failed would hybrid use of transcatheter valves be considered as an intraoperative bailout. Today, with help from structural heart interventionalists and advanced cardiac imaging, these hybrid procedures are now pre-planned, creating a novel treatment modality for once inoperable patients (3). Application of transcatheter technology in an open procedure can utilize the best of both worlds. Under direct vision, the anterior leaflet can be resected, a septal myectomy can be added to reduce risk of left ventricular outflow tract (LVOT) obstruction, and anchoring sutures can better secure the prosthesis. At the same time, the ability to balloon dilate means an extensive decalcification process is not necessary.

The technical aspect begins with advanced preoperative imaging to determine appropriate valve size and risk of LVOT obstruction. Intraoperatively, anchoring sutures are driven through the calcium bar if feasible, otherwise either periannular through leaflet tissue or around the calcium. An off-label Edwards Sapien 3 valve is then fitted with a felt cuff and the annular anchoring sutures are placed through both the cuff and valve stent to prevent device migration or embolization and limit PVL. The valve is then deployed and balloon dilated under direct vision within the annulus.

Despite the obvious benefits in challenging cases, there has been noticeably poor one year survival of these patients due to the overall higher baseline patient risk profile as well as the poor performance of these off-label devices in the mitral position (7).

Conclusions and future perspectives

This 2025 ECD on the surgical management of MAC comes at a time when advancements in surgical and transcatheter techniques have allowed us to offer more treatment modalities to these complex patients (Video 1). By bringing together the contributions of cardiac surgeons, cardiologists, and structural interventionalists, we can deliver safe and durable therapies to improve patient outcomes. Despite these advancements, more work remains to be done. At present, the use of transcatheter devices in an off-label setting has limited applicability often akin to fitting a square peg into a round hole. The development of MAC-specific devices for hybrid intervention would benefit the most complex patients unable to undergo conventional transcatheter or open surgical intervention. Creation of prospective, multicenter registries would provide the data and infrastructure necessary to critically assess which treatments work best, and to adapt practice accordingly. The consolidation of MAC experience at centers of expertise, like the concept of the valve reference center for mitral and aortic repair, and the deliberate teaching of trainees to disseminate this knowledge will allow the highest quality of care to reach the largest number of patients. Finally, given the current limitations of transcatheter technologies, MAC remains largely a surgical disease. Therefore, the focus should be on identifying patients who are surgical candidates and fitting them with the safest procedure according to their risk profile and the available surgical expertise.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Journal of Visualized Surgery. The article has undergone external peer review.

Peer Review File: Available at https://jovs.amegroups.com/article/view/10.21037/jovs-2026-1-0009/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jovs.amegroups.com/article/view/10.21037/jovs-2026-1-0009/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Written informed consent was obtained from the patients for the publication of this study, accompanying images and the video. A copy of the written consent is available for review by the editorial office of this journal.

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