Transatrial implantation of a transcatheter heart valve for severe mitral annular calcification

Valvular heart disease: from mechanisms to management

Valvular heart disease is common and its prevalence is rapidly increasing worldwide. Effective medical therapies are insufficient and treatment was historically limited to the surgical techniques of valve repair or replacement, resulting in systematic underprovision of care to older patients and those with substantial comorbidities, frailty, or left ventricular dysfunction. Advances in imaging and surgical techniques over the past 20 years have transformed the management of valvular heart disease. Better understanding of the mechanisms and causes of disease and an increasingly extensive and robust evidence base provide a platform for the delivery of individualised treatment by multidisciplinary heart teams working within networks of diagnostic facilities and specialist heart valve centres. In this Series paper, we aim to provide an overview of the current and future management of valvular heart disease and propose treatment approaches based on an understanding of the underlying pathophysiology and the application of multidisciplinary treatment strategies to individual patients.

Early outcomes following transatrial transcatheter mitral valve replacement in patients with severe mitral annular calcification

OBJECTIVE

Implantation of a transcatheter valve-in-mitral annular calcification (ViMAC) has emerged as an alternative to traditional surgical mitral valve (MV) replacement. Previous studies evaluating ViMAC aggregated transseptal, transapical, and transatrial forms of the procedure, leaving uncertainty about each technique's advantages and disadvantages. Thus, we sought to evaluate clinical outcomes specifically for transatrial ViMAC from the largest multicenter registry to-date.

METHODS

Patients with symptomatic MV dysfunction and severe MAC who underwent ViMAC were enrolled from 12 centers across the United States and Europe. Clinical characteristics, procedural details, and clinical outcomes were abstracted from the electronic record. The primary end point was all-cause mortality.

RESULTS

We analyzed 126 patients who underwent ViMAC (median age 76 years [interquartile range {IQR}, 70-82 years], 28.6% female, median Society of Thoracic Surgeons score 6.8% [IQR, 4.0-11.4], and median follow-up 89 days [IQR, 16-383.5]). Sixty-one (48.4%) had isolated mitral stenosis, 25 (19.8%) had isolated mitral regurgitation (MR), and 40 (31.7%) had mixed MV disease. Technical success was achieved in 119 (94.4%) patients. Thirty (23.8%) patients underwent concurrent septal myectomy, and 8 (6.3%) patients experienced left ventricular outflow tract obstruction (7/8 did not undergo myectomy). Five (4.2%) patients of 118 with postprocedure echocardiograms had greater than mild paravalvular leak. Thirty-day and 1-year all-cause mortality occurred in 16 and 33 patients, respectively. In multivariable models, moderate or greater MR at baseline was associated with increased risk of 1-year mortality (hazard ratio, 2.31; 95% confidence interval, 1.07-4.99, P = .03).

CONCLUSIONS

Transatrial ViMAC is safe and feasible in this selected, male-predominant cohort. Patients with significant MR may derive less benefit from ViMAC than patients with mitral stenosis only.

Transcatheter mitral valve implantation for native valve disease

Mitral regurgitation is the second most frequent heart valve disease in Europe and the most frequent in the US. Although surgery is the therapy of choice when intervention is indicated, transcatheter mitral valve repair or replacement are alternatives for patients who are not eligible for surgery. However, the development of transcatheter mitral valves is slower than expected. Although several transcatheter heart valves have been developed, only one has been commercialised. Indeed, most of these devices are being evaluated in clinical studies, with promising initial results. In this review, we propose an overview on transcatheter mitral valve replacement for the treatment of native mitral valve disease, from indication to results, including patients with severe annular calcification, and we provide you with a glimpse into the future of these therapies.

National trends in utilization of transatrial transcatheter mitral valve replacement and postoperative outcomes

OBJECTIVE

Transatrial transcatheter mitral valve replacement reduces complexity during mitral valve replacements involving high-risk patients with mitral annular calcification. This study examines trends in transatrial transcatheter mitral valve replacement use and outcomes.

METHODS

Patients in the Society of Thoracic Surgeons database from 2014 to 2021 with mitral annular calcification undergoing transatrial transcatheter mitral valve replacement were included. Exclusion criteria were hypertrophic cardiomyopathy, congenital mitral valve disease, ventricular assist device placement, or prior mitral valve surgery. Primary outcomes were operative mortality and major adverse cardiac events compared between the Early (2014-2017, N = 71) and Recent (2018-2021, N = 151) eras. Parsimonious multivariable regression assessed select possible confounders for trends in major adverse cardiac events.

RESULTS

Overall, 222 transatrial transcatheter mitral valve replacements at 104 hospitals were identified. Annual volume increased from 6 in 2014 to 43 in 2021. Median hospital volume was 1, maximum hospital volume was 17, and 10 or more replacements were performed at 4 hospitals. Mortality and major adverse cardiac events occurred in 10.4% and 22.5% of patients, respectively. Compared with the Early era patients, Recent era patients were more often elective (79.5% vs 64.8%) and were approached via sternotomy (90.1% vs 80.3%, all P < .05). Despite similar predicted risk of mortality (9.6% ± 11.1% vs 11.0% ± 6.0%; P = .61), Recent patients had reduced mortality (3.3% vs 25.4%, P < .001) and major adverse cardiac events (18.5% vs 31.0%; P = .057). On univariate and multivariable analyses, the Recent surgical era was significantly associated with lower mortality (0.10 [0.04-0.29]; P < .001) and lower major adverse cardiac events (0.48 [0.25-0.94]; P = .032), respectively. There were no preoperative characteristics that were significant confounders for the difference in major adverse cardiac events.

CONCLUSIONS

Mortality and major adverse cardiac events after transatrial transcatheter mitral valve replacement have decreased significantly in the contemporary era independent of changes in major patient and operative characteristics. Transatrial transcatheter mitral valve replacement will have a future role in patients with mitral annular calcification.

Diagnosis, Classification, and Management Strategies for Mitral Annular Calcification: A Heart Valve Collaboratory Position Statement

Mitral annular calcium (MAC) with severe mitral valvular dysfunction presents a complex problem, as valve replacement, either surgical or transcatheter, is challenging because of anatomy, technical considerations, concomitant comorbidities, and advanced age. The authors review the clinical and anatomical features of MAC that are favorable (green light), challenging (yellow light), or prohibitive (red light) for surgical or transcatheter mitral valve interventions. Under the auspices of the Heart Valve Collaboratory, an expert working group of cardiac surgeons, interventional cardiologists, and interventional imaging cardiologists was formed to develop recommendations regarding treatment options for patients with MAC as well as a proposed grading and staging system using both anatomical and clinical features.

Transcatheter Mitral Valve Replacement in Patients with Mitral Annular Calcification: A Review

Mitral annular calcification (MAC) is a progressive degenerative calcification of the mitral valve (MV) that is associated with mitral stenosis, regurgitation or both. Patients with MAC are poor candidates for MV surgery because of technical challenges and high peri-operative mortality. Transcatheter MV replacement (TMVR) has emerged as an option for such high surgical risk patients. This has been described with the use of the SAPIEN transcatheter heart valve (valve-in-MAC) and dedicated TMVR devices. Careful anatomic assessment is important to avoid complications of TMVR, such as left ventricular outflow tract obstruction, valve migration, embolization and paravalvular mitral regurgitation. In this review, we discuss the pathology, importance of preprocedural multimodality imaging for optimal patient selection, clinical outcomes and complications associated with TMVR in patients with MAC.

Flow dynamic assessment of native mitral valve, mitral valve repair and mitral valve replacement using vector flow mapping intracardiac flow dynamic in mitral valve regurgitation

Objectives

The present study aims to assess and describe the intracardiac blood flow dynamic in patients with mitral regurgitation (MR), repaired mitral valves (MV) and mitral valve prostheses using vector flow mapping (VFM).

Methods

Patients with different MV pathologies and MV disease treatments were analysed. All patients underwent 2D transthoracic echocardiography, and images for flow visualization were acquired in VFM mode in an apical three-chamber view and four-chamber view. Vectors and vortices were qualitatively analyzed.

Results

thirty-two (32) patients underwent 2D transthoracic echocardiography (TTE) with VFM analysis. We evaluated intracardiac flow dynamics in 3 healthy subjects, 10 patients with MR (5 degenerative, 5 functional), 4 patients who underwent MV repair, 5 who underwent MV replacement (3 biological, 2 mechanical), 2 surgically implanted transcatheter heart valve (THV), 2 transcatheter edge-to-edge MV repair with MitraClip (TEER), 3 transcatheter MV replacement (TMVR) and 3 transapical off-pump MV repair with NeoChord implantation. Blood flow patterns are significantly altered in patients with MV disease and MV repair compared to control patients. MV repair is superior to replacement in restoring more physiologicalpatterns, while TMVR reproducesan intraventricular flowcloser to normal than surgical MVR and TEER.

Conclusions

Intracardiac flow patterns can be clearly defined using VFM. Restoration of a physiological blood flow pattern inside the LV directly depends on the procedure used to address MV disease.

Mitral annular calcification in patients with significant mitral valve disease: An old problem with new solutions

Mitral annular calcification (MAC) is a chronic process involving mitral valve annulus, linked with an increased cardiovascular mortality and morbidity. Since its first autoptic description, a progressive evolution in diagnostic tools brought cardiac computed tomography (CT) scan to become the gold standard in MAC detection and classification. The treatment of significant mitral valve disease in patients with annular calcifications has always represented an issue for cardiac surgeons, being it linked with an increased risk of atrioventricular groove rupture, circumflex artery injury, or embolism. As a consequence, different surgical techniques have been developed over time in order to reduce the incidence of these fearsome complications. Recently, transcatheter mitral valve replacement (TMVR) has emerged as a valid alternative to surgery in high-risk patients. Both hybrid transatrial, transfemoral, or transapical approaches have been described to deliver balloon-expandable or self-expanding aortic transcatheter valves into the calcified annulus, with conflicting early and long-term results. Tendyne (Abbott Structural Heart, Santa Clara, CA, USA) is a promising transapical-delivered option. Early results have shown effectiveness and safety of this device in patients with MAC and severe mitral valve disease, with the lowest rate of embolization, mortality, and left ventricular outflow tract obstruction (LVOTO) reported so far.

Mitral valve stenosis in the current era: a changing landscape

Mitral stenosis results from haemodynamic obstruction at the mitral valve level because of structural abnormalities of the valve apparatus, leading to increased resistance to the transmitral flow. Although rheumatic fever remains the predominant cause of mitral stenosis worldwide, other causes are increasingly relevant in the developed countries with degenerative mitral stenosis (DMS) because of mitral annulus calcification (MAC) becoming growingly prevalent in industrialized countries with higher life expectancy. Rheumatic mitral stenosis (RMS) and DMS display dramatic differences in pathophysiology, prognosis, and disease progression. Furthermore, to date, robust evidence regarding the management of DMS because of MAC is lacking. Nevertheless, new diagnostic techniques and catheter-based interventions are changing this landscape and paving the way to a significant reduction in DMS-related morbidity and mortality. Here we briefly review the current knowledge on the pathophysiology, diagnosis and treatment of DMS and RMS, underscoring the current diagnostic and therapeutic pathways, as well as persisting uncertainties and perspectives.

Management of Patients With Severe Mitral Annular Calcification: JACC State-of-the-Art Review

Mitral annular calcification (MAC) is a common and challenging pathologic condition, especially in the context of an aging society. Surgical mitral valve intervention in patients with MAC is difficult, with varying approaches to the calcified annular anatomy, and the advent of transcatheter valve interventions has provided additional treatment options. Advanced imaging provides the foundation for heart team discussions and management decisions concerning individual patients. This review focuses on the prognosis of, preoperative planning for, and management strategies for patients with MAC.

Right Mini-Thoracotomy Beating Heart Mitral Valve Replacement with a SAPIEN 3 Valve for Severe Circumferential Mitral Annular Calcification

Mitral annular calcification (MAC) is a degenerative process that can cause mitral valve stenosis. Conventional surgical mitral valve replacement (MVR) for MAC with mitral stenosis can be challenging and associated with significant risk. Open surgical MVR with a transcatheter valve can offer an alternative in select situations. When such a strategy is not feasible, a beating-heart, mini-thoracotomy MVR with a SAPIEN 3 transcatheter heart valve can be considered. The novel teaching point of this case is use of an alternative approach for managing severe mitral stenosis secondary to MAC, when conventional surgical and transcatheter strategies are not safe or possible.

Minimally Invasive Mitral Valve Surgery After Transcatheter Edge-to-Edge Repair

OBJECTIVE

Up to 28% of patients may need mitral valve (MV) surgery after transcatheter edge-to-edge repair (TEER). This study evaluates the outcomes of minimally invasive MV surgery after TEER. Methods: International multicenter registry of minimally invasive MV surgery after TEER between 2013 and 2020. Subgroups were stratified by the number of devices implanted (≤1 vs >1), as well as time interval from TEER to surgery (≤1 year vs >1 year). Results: A total of 56 patients across 13 centers were included with a mean age of 73 ± 11 years, and 50% were female. The median Society of Thoracic Surgeons Predicted Risk of Mortality (STS PROM) score for MV replacement was 8% (Q1-Q3 = 5% to 11%) and the ratio of observed to expected mortality was 0.9. The etiology of mitral regurgitation (MR) prior to TEER was primary MR in 75% of patients and secondary MR in 25%. There were 30 patients (54%) who had >1 device implanted. The median time between TEER and surgery was 252 days (33 to 636 days). Hemodynamics, including MR severity, MV area, and mean gradient, significantly improved after minimally invasive surgery and sustained to 1-year follow-up. In-hospital and 30-day mortality was 7.1%, and 1-year actuarial survival was 85.6% ± 6%. Conclusions: Minimally invasive MV surgery after TEER may be achieved as predicted by the STS PROM. Most patients underwent MV replacement instead of repair. As TEER is applied more widely, patients should be informed about the potential need for surgical intervention over time after TEER. These discussions will allow better informed consent and post-procedure planning.

Hybrid Surgery for Severe Mitral Valve Calcification: Limitations and Caveats for an Open Transcatheter Approach

Background and Objectives: Mitral stenosis with extensive mitral annular calcification (MAC) remains surgically challenging in respect to clinical outcome. Prolonged surgery time with imminent ventricular rupture and systolic anterior motion can be considered as a complex of causal factors. The aim of our alternative hybrid approach was to reduce the risk of annual rupture and paravalvular leaks and to avoid obstruction of the outflow tract. A review of the current literature was also carried out. Materials and Methods: Six female patients (mean age 76 ± 9 years) with severe mitral valve stenosis and severely calcified annulus underwent an open implantation of an Edwards Sapien 3 prosthesis on cardiopulmonary bypass. Our hybrid approach involved resection of the anterior mitral leaflet, placement of anchor sutures and the deployment of a balloon expanded prosthesis under visual control. Concomitant procedures were carried out in three patients. Results: The mean duration of cross-clamping was 95 ± 31 min and cardiopulmonary bypass was 137 ± 60 min. The perioperative TEE showed in three patients an inconspicuous, heart valve-typical gradient on all implanted prostheses and a clinically irrelevant paravalvular leakage occurred in the anterior annulus. In the left ventricular outflow tract, mild to moderately elevated gradients were recorded. No adverse cerebrovascular events and pacemaker implantations were observed. All but one patient survived to discharge. Survival at one year was 83.3%. Conclusions: This “off label” implantation of the Edwards Sapien 3 prosthesis may be considered as a suitable bail-out approach for patients at high-risk for mitral valve surgery or deemed inoperable due to extensive MAC.

Open transcatheter valve implantation for mitral annular calcification: One-year outcomes

Background

Transcatheter mitral valve implantation (TMVI) for native mitral valve pathology with severe mitral annular calcification has emerged as an alternative treatment option to conventional mitral valve surgery. The objective of this study was to evaluate patients who were referred for TMVI with severe mitral annular calcification and their procedural outcomes.

Methods

Retrospective analysis of patients from 2017 to 2020 referred for TMVI was carried out. Demographic characteristic details; surgical strategy; perioperative complications; and hospital stay, including 30-day and 1-year mortality, were analyzed.

Results

Eleven patients were referred for consideration of TMVI. The 8 patients who underwent TMVI had a median age of 74 years (range, 57-80 years), the median Society of Thoracic Surgeons score was 4.6 (range, 2.4-10.9), and European System for Cardiac Operative Risk Evaluation II score was 5.2% (2%-10.1%). The median cardiopulmonary bypass time and crossclamp times were 170 minutes (range, 150-248 minutes) and 152 minutes (range, 118-214 minutes), respectively. The median hospital stay was 29 days (range, 2-40 days). Thirty-day in hospital mortality was 12%, whereas 1-year mortality was 25%. There was symptomatic improvement with downgrade of New York Heart Association functional class from III or IV to I or II. The 3 patients who were turned down had a median age of 73 years, median Society of Thoracic Surgeons score was 13.4, and median European System for Cardiac Operative Risk Evaluation II score was 5.72%. They were alive at 12 months follow-up from the date of surgical assessment; however, all with New York Heart Association functional class III or IV symptoms.

Conclusions

We describe a series demonstrating the technical consideration and capability of transatrial TMVI to treat mitral annular calcification and native mitral valve disease. Our results are favorable when compared with TMVI global registry data for transseptal or transapical approach.

Early outcomes of transatrial mitral valve replacement in severe mitral annular calcification

Objective

Mitral valve replacement (MVR) in the setting of severe mitral annular calcification is a technically challenging operation with increased morbidity and mortality. Transseptal/apical transcatheter MVR (TMVR) in mitral annular calcification has emerged as an option for these cases, although may not be feasible due to anatomical reasons. Transatrial TMVR is a potential treatment option for this subgroup of patients.

Methods

Patients who underwent transatrial TMVR between June 2018 and November 2020 at a single institution were included. Patients were selected by a structural heart team based on their surgical risk, pattern of mitral annular calcification, risk of valve migration, left ventricular outflow obstruction, and paravalvular leak.

Results

A total of 11 patients underwent transatrial TMVR. Mean patient age was 74.2 years and mean Society of Thoracic Surgeons predicted risk of mortality score was 9.1%. All patients had the presence of both mitral stenosis and regurgitation—dominant etiology—was mitral stenosis in 81.2%, and mitral regurgitation in 18.8%. Among patients, 54.5% had a concomitant cardiac procedure. There was no in-hospital or 30-day mortality. Technical success defined by the Mitral Valve Academic Research Consortium was achieved in 90.9% of patients. Postoperative paravalvular leak was mild or less in all patients.

Conclusions

In this series, transatrial TMVR was shown to be a safe and effective treatment option for patients who are high risk for surgical MVR and should be in surgeons' armamentarium in the treatment of this high-risk patient population. Dissemination of safe technique will be critical in the successful conduct of this surgery.

Transcatheter mitral valve replacement for degenerated mitral valve bioprostheses, failure of mitral valvuloplasty and native valve with severe mitral annulus calcification: a systematic review and meta-analysis

Background

Although transcatheter technology has achieved some success in the field of mitral valves, the feasibility of applying it to patients with degenerated mitral valve bioprostheses (valve-in-valve, ViV), failure of mitral valvuloplasty (valve-in-ring, ViR) and serious mitral annulus calcification (vale-in-MAC, ViMAC) has not been effectively evaluated.

Methods

By searching published literature before December 5, 2020 in four databases, we found all the literature related to the evaluation of feasibility assessment of TMViV, TMViR and TMViMAC. Outcomes focused on all-cause mortality within 30 days, bleeding and LVOT obstruction.

Results

A total of six studies were included, and all of them were followed up for at least 30 days. After analysis of the ViV–ViR group, we obtained the following results: the all-cause mortality within 30 days of the ViV group was lower than that of the ViR group. Life-threatening or fatal bleeding was more likely to occur in the ViR group after surgery. At the same time, the ViR group was more prone to left ventricular outflow tract obstruction. However, in the ViMAC–ViR group, only the all-cause mortality within 30 days and stroke were statistically significant. In the indirect comparison, we found that TMViV had the best applicability, followed by TMViR. There were few TMViMAC available for analysis, and it requires further studies to improve the accuracy of the results.

Conclusion

TMViV and TMViR had good applicability and could benefit patients who underwent repeat valve surgery. The feasibility of TMViMAC needs to be further explored and improved.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-021-01677-7.

Surgical implantation of balloon-expandable heart valves for the treatment of mitral annular calcification

OBJECTIVES

The treatment of mitral valve disease in the presence of mitral annular calcification (MAC) is associated with an increased risk of cardiovascular and all-cause mortality. Various surgical and transcatheter techniques for the treatment of mitral disease with severe MAC have been described. However, these procedures are associated with high risk of operative morbidity and mortality. We describe our experience with open surgical implantation of a balloon-expandable valve (BEV) in patients with severe MAC as an alternative approach.

METHODS

BEV implantation was performed with direct vision through the left atrium via a median sternotomy or minimally invasive approach. The midportion of the anterior leaflet is excised, and a ventricular septal myectomy performed if there is high risk for left ventricular outflow tract obstruction. The primary outcome was technical success according to the Mitral Valve Academic Research Consortium criteria; secondary outcomes were 30-day and 1-year mortality.

RESULTS

From October 2015 through October 2020, 51 patients at 2 institutions underwent BEV-in-MAC (mean age, 73.9 ± 8.8 years; 60.8% [31/51] were female; mean Society of Thoracic Surgeons predicted risk of mortality: 6.8% ± 4.8%). Technical success was 94.1% (48/51). Thirty-day and 1-year mortality were 13.7% (7/51) and 33.3% (15/45), and for stroke 3.9% (2/51) and 4.4% (2/45), respectively.

CONCLUSIONS

Surgical implantation of a BEV in the mitral position offers a treatment option for patients with mitral valve disease complicated by severe MAC who are at increased risk for conventional surgical approaches and at risk for left ventricular outflow tract obstruction with transcatheter approaches.

How to Manage Mitral Stenosis Due to Mitral Annular Calcification

PURPOSE OF REVIEW

Mitral annular calcification (MAC) is associated with cardiovascular comorbidities and events and in the presence of mitral stenosis (MS) represents a high-risk cohort with limited treatment options. Emerging hybrid, minimally invasive, and transcatheter therapies that use circumferential MAC as an anchor for mitral valve replacement are emerging, but none are consistently associated with ideal outcomes.

RECENT FINDINGS

In patients with MAC and nonrheumatic calcific mitral stenosis who are severely symptomatic, mitral intervention may be indicated. Surgical decalcification and replacement of the mitral valve remains the conventional therapy. Surgical techniques to avoid decalcification are being described including a left atrium to left ventricular apex graft conduit. Transcatheter balloon-expandable valves designed for the aortic valve have been implanted in the mitral position in MAC with a surgical direct transatrial transcatheter approach or transseptal transcatheter approach. Left ventricular outflow tract (LVOT) obstruction remains prevalent and associated with increased mortality. Direct transatrial approach allows for surgical resection of the anterior leaflet to mitigate this risk, and percutaneous therapies to lacerate the anterior leaflet or to ablate the basal septum are being developed. Cardiac computed tomography has emerged as a requisite for patient selection and procedural planning and has powerful predictive value for LVOT obstruction and valve embolization in valve-in-MAC. Novel transcatheter valves designed specifically for the mitral space are being studied in patients with MAC. MAC with mitral stenosis remains a challenging disease. Advances in technique, technology, and imaging may create new and reproducible treatment options with low procedural mortality for this challenging disease entity.

CT for Pre- and Postprocedural Evaluation of Transcatheter Mitral Valve Replacement

Transcatheter mitral valve replacement (TMVR) is a catheter-based interventional technique for treating mitral valve disease in patients who are at high risk for open mitral valve surgery and with unfavorable anatomy for minimally invasive edge-to-edge transcatheter mitral valve repair. There are several TMVR devices with different anchoring mechanisms, delivered by either transapical or transseptal approaches. Transthoracic echocardiography is the first-line imaging modality used for characterization and quantification of mitral valve disorders. CT is complementary to echocardiography and has several advantages, including high isotropic spatial resolution, good temporal resolution, large field of view, multiplanar reconstruction capabilities, and rapid turnaround time. CT is essential for multiple aspects of preprocedural planning. Accurate and reproducible techniques to prescribe the mitral annulus at CT have been described from which important measurements such as the area, perimeter, trigone-trigone distance, intercommissural distance, and septolateral distance are obtained. The neo-left ventricular outflow tract (LVOT) can be simulated by placing a virtual prosthesis in the CT data to predict the risk of TMVR-induced LVOT obstruction. The anatomy of the landing zone and subvalvular apparatus as well as the relationship of the virtual device to adjacent structures such as the coronary sinus and left circumflex coronary artery can be evaluated. CT also stimulates procedural fluoroscopic angles. CT can be used to evaluate the chest wall for transapical access and the atrial septum for transseptal access. Follow-up CT is useful in identifying complications such as LVOT obstruction, paravalvular leak, pseudoaneurysm, and valve embolization. Online supplemental material is available for this article. ^©RSNA, 2020.

Current Devices and Complications Related to Transcatheter Mitral Valve Replacement: The Bumpy Road to the Top

Mitral regurgitation is the most common valvular lesion in the developed world, with increasing prevalence, morbidity, and mortality. The experience with surgical mitral valve repair or replacement is very well-validated. However, more than 45% of these patients get denied surgery due to an elevated risk profile and advanced disease of the left ventricle at the time of presentation, promoting the need for less invasive transcatheter options such as transcatheter repair and transcatheter mitral valve replacement (TMVR). Early available TMVR studies have shown promising results, and several dedicated devices are under clinical evaluation. However, TMVR is still in the early developmental stages and is associated with a non-negligible risk of periprocedural and post-procedural complications. In this review, we discuss the current challenges facing TMVR and the potential TMVR-related complications, offering an overview on the measures implemented to mitigate these complications, and future implications.

Systematic Approach to the Calcified Mitral Valve Apparatus at Time of Mitral Valve Replacement

Mitral annular calcification (MAC) represents a surgical challenge to mitral valve replacement. The presence of MAC at the time of mitral valve replacement is associated with perivalvular leak and atrial-ventricular groove injury. Although percutaneous and hybrid approaches may offer alternatives to surgical mitral valve replacement, the early and late results from these techniques remain unknown. As such, the surgical management of MAC remains relevant in the contemporary treatment of patients with MAC. Herein, we present a systematic approach to the management of MAC at the time of mitral valve replacement.

Surgical and Transcatheter Mitral Valve Replacement in Mitral Annular Calcification: A Systematic Review

Mitral annular calcification with mitral valve disease is a challenging problem that could necessitate surgical mitral valve replacement (SMVR). Transcatheter mitral valve replacement (TMVR) is emerging as a feasible alternative in high-risk patients with appropriate anatomy. PubMed, Embase, and Cochrane Central Register of Controlled Trials were searched from inception to December 25, 2019 for studies discussing SMVR or TMVR in patients with mitral annular calcification; 27 of 1539 articles were selected for final review. TMVR was used in 15 studies. Relevant data were available on 82 patients who underwent hybrid transatrial TMVR, and 354 patients who underwent transapical or transseptal TMVR. Outcomes on SMVR were generally reported as small case series (447 patients from 11 studies); however, 1 large study recently reported outcomes in 9551 patients. Patients who underwent TMVR had a shorter median follow-up of 9 to 12 months (range, in-hospital‒19 months) compared with patients with SMVR (54 months; range, in-hospital‒120 months). Overall, those undergoing TMVR were older and had higher Society of Thoracic Surgeons risk scores. SMVR showed a wide range of early (0%-27%; median 6.3%) and long-term mortality (0%-65%; median at 1 year, 15.8%; 5 years, 38.8%, 10 years, 62.4%). The median in-hospital, 30-day, and 1-year mortality rates were 16.7%, 22.7%, and 43%, respectively, for transseptal/transapical TMVR, and 9.5%, 20.0%, and 40%, respectively, for transatrial TMVR. Mitral annular calcification is a complex disease and TMVR, with a versatile option of transatrial approach in patients with challenging anatomy, offers a promising alternative to SMVR in high-risk patients. However, further studies are needed to improve technology, patient selection, operative expertise, and long-term outcomes.

Anatomic classification of mitral annular calcification for surgical and transcatheter mitral valve replacement

BACKGROUND AND AIM OF THE STUDY: A systematic approach to quantify mitral annular calcification (MAC) in all-comers by multidetector computed tomography (MDCT) is essential to guide treatment, but lacking.

METHODS

From September 2015 to July 2019, 82 patients with MAC underwent MDCT at two institutions to evaluate for surgical mitral valve replacement (SMVR), transcatheter mitral valve replacement (TMVR), or medical management. Type 1 MAC was defined as <270° annular calcium and Type 2 as ≥270°. Absence/presence of predicted left ventricular outflow tract (LVOT) obstruction with virtual valve placement was used to further define Type 2 MAC into 2A/B for our treatment algorithm.

RESULTS

Type 1 MAC was present in 51.2%, Type 2A in 18.3%, and Type 2B in 30.5%. Operable Type 1 patients (50.0%) underwent hybrid transatrial TMVR or SMVR. Type 2A underwent a variety of treatments, and Type 2B surgical candidates (40.0%) underwent hybrid transatrial TMVR secondary to difficult suture anchoring with significant MAC and predicted LVOT obstruction. At a follow-up of 29.6 ± 12.0 months, mortality was 42.7% with 46.3% in the intervention group and 39.0% in the medical group (p = 0.47). All percutaneous TMVR patients expired. This translated to a disproportionate number of Type 2A deaths (80.0% with intervention), but all were high/extreme surgical risk. The hybrid TMVR group consisted of 95.0% Type 1/2B patients and had a lower Society of Thoracic Surgeons predicted risk of operative mortality (7.4% vs. 9.2%, p = 0.43)/mortality.

CONCLUSIONS

The highest mortality was seen in percutaneous TMVR Type 2A MAC patients, but they were at the greatest risk. Here we provide an objective MAC treatment algorithm for all-comers based on operability/anatomy.

Current Indications for Transcatheter Mitral Valve Replacement Using Transcatheter Aortic Valves

Use of transcatheter mitral valve replacement (TMVR) using transcatheter aortic valves in clinical practice is limited to patients with failing bioprostheses and rings or mitral valve disease associated with severe mitral annulus calcification. Whereas the use of valve-in-valve TMVR appears to be a reasonable alternative to surgery in patients at high surgical risk, much less evidence supports valve-in-ring and valve-in-mitral annulus calcification interventions. Data on the results of TMVR in these settings are derived from small case series or voluntary registries. This review summarizes the current evidence on TMVR using transcatheter aortic valves in clinical practice from the characteristics of the TMVR candidates, screening process, performance of the procedure, and description of current results and future perspectives. TMVR using dedicated devices in native noncalcified mitral valve diseases is beyond the scope of the article.

Double-Valve Replacement in Patients With Mitral Annular Calcification and Aortic Stenosis

Mitral annular calcification (MAC) is a degenerative process of the fibrous structure of the mitral valve. Surgical mitral valve replacement in the presence of MAC is technically challenging because of a high calcium burden and is associated with prohibitive operative mortality. There is no standard management strategy for patients with severe aortic stenosis and severe mitral valve disease with MAC. We report a case series of 3 patients who underwent concomitant surgical, transatrial implantation of a transcatheter heart valve in the mitral position and transcatheter aortic valve replacement.

Clinical impact of mitral calcium volume in patients undergoing transcatheter aortic valve implantation

BACKGROUND

Mitral annular calcification (MAC) has been associated with mitral valve (MV) disease and cardiovascular events in patients undergoing transcatheter aortic valve implantation (TAVI). We aimed to investigate the incidence and impact of mitral calcium volume (MCV) quantified by multidetector computed tomography (MDCT) on MV function and clinical outcomes after TAVI.

METHODS

Consecutive patients with exploitable echocardiography and MDCT performed during TAVI screening were enrolled in this retrospective analysis. Mitral calcium was assessed visually and measured using a semi-automatic tool developed for the aortic valve in an off-label fashion.

RESULTS

MCV >0 mm³ was found in 65% of the 875 included patients. Patients with calcification were older (82 ± 6 versus 81 ± 7; P = 0.002) and had high prevalence of renal dysfunction (69% versus 61%; P = 0.017) and mitral stenosis (25% versus 4%, P < 0.001). MCV correlated well with visual MAC severity (r = 0.94; P < 0.001), but showed a greater predictive value for mitral stenosis (AUC = 0.804 vs. 0.780, P = 0.012) , while it was not a predictor of mitral regurgitation (AUC = 0.514). Correlations were found between MCV and echocardiographic parameters including MV area, mean transmitral gradient, and pressure half-time (P < 0.001 for all). MCV did not impact on cardiovascular mortality or new permanent pacemaker implantation after TAVI.

CONCLUSIONS

Calcification of the mitral apparatus is common in TAVI candidates and results in mitral stenosis in 25% of the patients. Increasing MCV predicts mitral stenosis, but had no impact on clinical outcomes following TAVI.

CLINICAL TRIAL REGISTRATION

NCT01368250.

Transcatheter Mitral Valve Replacement: Procedural Planning, Utility, and Applicability

Since the first native transcatheter mitral valve implantation in 2012, transcatheter mitral valve replacement (TMVR) has expanded its use to degenerated bioprostheses, failed annuloplasty ring repair, and mitral annular calcification. However, high-screen failure rates in trials have persisted due to predicted left ventricular outflow tract obstruction and unfavorable anatomy. Preprocedural planning in this patient population with multidetector computed tomography and transesophageal echocardiography is paramount to intraprocedural success. In patients with favorable left ventricular outflow tract anatomy who are not surgical candidates, the transseptal approach is preferred. In those who are surgical candidates, TMVR can be performed via a transapical or transatrial approach. Currently, a plethora of TMVR devices targeting the native mitral pathologies are undergoing clinical trials. Data have consistently shown the greatest benefit of this procedure in native mitral regurgitation and failed bioprostheses rather than failed annuloplasty rings or mitral annular calcification. With technological advancement and careful patient selection, this therapy will serve as a complement to surgical and TMV repair and will continue to expand to address MV diseases in a broader patient population.

Contemporary Surgical and Transcatheter Management of Mitral Annular Calcification

BACKGROUND

The presence of mitral annular calcification (MAC) in patients with mitral valve (MV) stenosis or regurgitation is a difficult scenario for surgeons and the heart team. Patients with MAC most often have a significant number of comorbidities that exclude them as surgical candidates. This review highlights the various contemporary techniques available to manage MAC during treatment of the MV.

METHODS

This study is a focused review of the anatomy, pathology, and management of MAC. The review describes the surgical and transcatheter techniques with outcomes, where available.

RESULTS

The incidence of MAC is between 5% and 42% in patients with severe MV disease. The pathophysiology underlying MAC is not yet clear, but it most likely is related to processes of inflammation and atherosclerosis. Surgical techniques can be grouped into those in which the MAC is completely resected en bloc and those in which the MAC is incompletely resected or left in situ. Transcatheter therapies are feasible in some patients, but they have been limited by the anatomic constraints of MAC; most importantly left ventricular outflow tract obstruction and paravalvular regurgitation.

CONCLUSIONS

Surgeons as part of the heart team now have a range of techniques to manage MAC in those patients with severe MV disease. Transcatheter therapies may increase the options for patients whose surgical risk is too high.

Mitral annular calcification: challenges and future perspectives

Mitral annular calcification (MAC) is a chronic degenerative process that implies calcification on the mitral support structure. It usually appears as a bystander to other cardiac pathologies hindering surgical treatment and increasing morbidity and mortality. When addressing the mitral valve, many surgical strategies have been suggested in the past with no clear consensus on what to choose. Moreover, and as transcatheter therapies have gained popularity over the last few decades, transcatheter mitral valve implantation has appeared as another alternative to conventional surgery. In this review, we aim at describing an overview of MAC, highlighting current challenges and treatment options as well as new potential alternatives.

BATMAN-Savior or vigilante?

BATMAN is a new technique to prevent left ventricular outflow tract (LVOT) obstruction from transcatheter mitral valve replacement (TMVR) by deploying the transcatheter heart valve from the apex through a perforation of the anterior mitral valve leaflet. The risks of uncontrolled balloon dilatation of the anterior mitral valve leaflet include extension of the tear superiorly into the aorto-mitral curtain or laterally to avulse the trigone from the annulus. Percutaneous laceration of the anterior mitral leaflet, pre-emptive alcohol septal ablation, and transatrial leaflet resection are alternative strategies that prevent LVOT obstruction from TMVR.

Mitral Annular Calcification: Association with Atherosclerosis and Clinical Implications

PURPOSE OF REVIEW

This review summarizes the pathophysiology of mitral annular calcification (MAC) with recent findings and current strategies for diagnosis and treatment.

RECENT FINDINGS

Major factors in MAC development seem to be shear stress of the flow past the mitral valve, local inflammation, and dysregulation in regulators of mineral metabolism. MAC itself poses daunting technical challenges. Implanting a valve on top of the calcium bar might lead to paravalvular leak (PVL) that is less likely to heal. Annular decalcification allows for better valve seating and potentially better healing and less PVL. This, however, comes with the risk for catastrophic atrioventricular groove disruption. MAC can be sharply dissected with the scalpel; the annulus can be reconstructed with the autologous pericardium. Transcatheter mitral valve replacement is a promising approach in the treatment of patients who are deemed high-risk surgical candidates with severe MAC. MAC is a multifactorial disease that has some commonalities with atherosclerosis, mainly regarding lipid accumulation and calcium deposition. It is of great clinical importance, being a risk marker of cardiovascular events (including sudden death) and, with its progression, can have a negative impact on patients' lives.