Anterior mitral leaflet laceration using the MitraCut technique for transapical transcatheter Tendyne implantation after unsuccessful Carillon indirect annuloplasty: a case report

Background

The introduction of a transapical transcatheter beating heart replacement system has significantly expanded therapeutic options for patients with severely diseased mitral valves, particularly those ineligibles for traditional surgery or transcatheter repair. However, challenges, such as left ventricular outflow tract obstruction (LVOT-O) and the risk of dynamic systolic anterior motion (SAM) in cases with elongated anterior mitral leaflet (AML) post-prosthesis implantation, impede the widespread adoption of transcatheter mitral valve replacement (TMVR).

Case summary

In 2022, a 75-year-old male with severe mixed-genesis mitral regurgitation (MR) underwent Carillon Mitral Contour System annuloplasty. Recurrent heart failure admissions (New York Heart Association IV) and prohibitive risk for open-heart surgery (European System for Cardiac Operative Risk Evaluation II 8.27%) prompted evaluation for Tendyne TMVR with the MitraCut technique. This beating heart transapical approach involved scissor-mediated splitting of the elongated 27 mm AML, essential for mitigating LVOT-O risk and dynamic SAM. The screening echocardiogram revealed the poorly tethered AML near the thickened septum at the simulated neo-LVOT site.

Discussion

This case underscores the intricate management challenges associated with severe MR, highlighting the successful application of the MitraCut technique as a viable alternative in high-risk scenarios. The imperative for further research and clinical studies is emphasized to comprehensively elucidate outcomes and safety parameters, providing valuable insights for refining TMVR applications within this context.

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.

Transcatheter Mitral Valve Replacement Using Transcatheter Aortic Valve or Dedicated Devices: Current Evidence and Future Prospects

Transcatheter mitral valve replacement (TMVR) is a novel and evolving field dedicated to addressing the therapeutic challenges posed by patients at high surgical risk with mitral valve disease. TMVR can be categorized into two distinct fields based on the type of device and its specific indications: TMVR with transcatheter aortic valves (TAV) and TMVR with dedicated devices. Similar to aortic stenosis, TMVR with TAV requires a rigid support structure to secure the valve in place. As a result, it is indicated for patients with failing bioprothesis or surgical rings or mitral valve disease associated with severe mitral annular calcification (MAC), which furnishes the necessary foundation for valve anchoring. While TMVR with TAV has shown promising outcomes in valve-in-valve procedures, its effectiveness remains more contentious in valve-in-ring or valve-in-MAC procedures. Conversely, TMVR with dedicated devices seeks to address native mitral regurgitation, whether accompanied by MAC or not, providing an alternative to Transcatheter Edge-to-Edge Repair (TEER) when TEER is not feasible or expected to yield unsatisfactory results. This emerging field is gradually surmounting technical challenges, including anchoring a valve in a non-calcified annulus and transitioning from the transapical route to the transeptal approach. Numerous devices are presently undergoing clinical trials. This review aims to furnish an overview of the supporting evidence for TMVR using TAV in each specific indication (valve-in-valve, valve-in-ring, valve-in-MAC). Subsequently, we will discuss the anticipated benefits of TMVR with dedicated devices over TEER, summarize the characteristics and clinical results of TMVR systems currently under investigation, and outline future prospects in this field.

Contemporary Treatment and Outcomes of High Surgical Risk Mitral Regurgitation

Before the development of transcatheter interventions, patients with mitral regurgitation (MR) and high surgical risk were often conservatively treated and subject to poor prognoses. We aimed to assess the therapeutic approaches and outcomes in the contemporary era. The study participants were consecutive high-risk MR patients from April 2019 to October 2021. Among the 305 patients analyzed, 274 (89.8%) underwent mitral valve interventions, whereas 31 (10.2%) received medical therapy alone. Of the interventions, transcatheter edge-to-edge mitral repair (TEER) was the most frequent (82.0% of overall), followed by transcatheter mitral valve replacement (TMVR) (4.6%). In patients treated with medical therapy alone, non-optimal morphologies for TEER and TMVR were shown in 87.1% and 65.0%, respectively. Patients undergoing mitral valve interventions experienced less frequent heart failure (HF) rehospitalization compared to those with medical therapy alone (18.2% vs. 42.0%, p < 0.01). Mitral valve intervention was associated with a lower risk of HF rehospitalization (HR 0.36 [0.18-0.74]) and an improved New York Heart Association class (p < 0.01). Most high-risk MR patients can be treated with mitral valve interventions. However, approximately 10% remained on medical therapy alone and were considered as unsuitable for current transcatheter technologies. Mitral valve intervention was associated with a lower risk of HF rehospitalization and improved functional status.

Transcatheter mitral valve replacement or repair for secondary mitral regurgitation: a propensity score-matched analysis

AIMS

This study aimed to compare outcomes after transcatheter mitral valve replacement (TMVR) and mitral valve transcatheter edge-to-edge repair (M-TEER) for the treatment of secondary mitral regurgitation (SMR).

METHODS AND RESULTS

The CHOICE-MI registry included 262 patients with SMR treated with TMVR between 2014 and 2022. The EuroSMR registry included 1065 patients with SMR treated with M-TEER between 2014 and 2019. Propensity score (PS) matching was performed for 12 demographic, clinical and echocardiographic parameters. Echocardiographic, functional and clinical outcomes out to 1 year were compared in the matched cohorts. After PS matching, 235 TMVR patients (75.5 years [70.0, 80.0], 60.2% male, EuroSCORE II 6.3% [interquartile range 3.8, 12.4]) were compared to 411 M-TEER patients (76.7 years [70.1, 80.5], 59.0% male, EuroSCORE II 6.7% [3.9, 12.4]). All-cause mortality was 6.8% after TMVR and 3.8% after M-TEER at 30 days (p = 0.11), and 25.8% after TMVR and 18.9% after M-TEER at 1 year (p = 0.056). No differences in mortality after 1 year were found between both groups in a 30-day landmark analysis (TMVR: 20.4%, M-TEER: 15.8%, p = 0.21). Compared to M-TEER, TMVR resulted in more effective mitral regurgitation (MR) reduction (residual MR ≤1+ at discharge for TMVR vs. M-TEER: 95.8% vs. 68.8%, p < 0.001), and superior symptomatic improvement (New York Heart Association class ≤II at 1 year: 77.8% vs. 64.3%, p = 0.015).

CONCLUSION

In this PS-matched comparison between TMVR and M-TEER in patients with severe SMR, TMVR was associated with superior reduction of MR and superior symptomatic improvement. While post-procedural mortality tended to be higher after TMVR, no significant differences in mortality were found beyond 30 days.

Feasibility evaluation of the transapical saddle-shaped valved stent for transcatheter mitral valve implantation

Background and Aims of Study

Transcatheter mitral valve implantation (TMVI) is a promising and minimally invasive treatment for high‐risk mitral regurgitation. We aimed to investigate the feasibility of a novel self‐expanding valved stent for TMVI via apical access.

Methods

We designed a novel self‐expanding mitral valve stent system consisting of an atrial flange and saddle‐shaped ventricular body connected by two opposing anchors and two opposing extensions. During valve deployment, each anchor was controlled by a recurrent string. TMVI was performed in 10 pigs using the valve prosthesis through apical access to verify technical feasibility. Echocardiography and ventricular angiography were used to assess hemodynamic data and valve function. Surviving pigs were killed 4 weeks later to confirm stent deployment.

Results

Ten animals underwent TMVI using the novel mitral valve stent. Optimal valve deployment and accurate anatomical adjustments were obtained in nine animals. Implantation failed in one case, and the animal died 1 day later due to stent mismatch. After stent implantation, the hemodynamic parameters of the other animals were stable, and valve function was normal. The mean pressure across the mitral valve and left ventricular outflow tract were 2.98 ± 0.91 mmHg and 3.42 ± 0.66 mmHg, respectively. Macroscopic evaluation confirmed the stable and secure positioning of the stents. No obvious valve displacement, embolism, or paravalvular leakage was observed 4 weeks postvalve implantation.

Conclusions

This study demonstrated that the novel mitral valve is technically feasible in animals. However, the long‐term feasibility and durability of this valved stent must be improved and verified.

Causes and predictors of mortality after transcatheter mitral valve implantation in patients with severe mitral annulus calcification

OBJECTIVES

To evaluate the causes and predictors of mortality after valve-in-mitral annulus calcification (MAC) transcatheter mitral valve implantation (TMVI).

BACKGROUND

Conventional surgical mitral valve replacement is associated with a high risk in patients with mitral valve disease associated with severe MAC. In this population, TMVI may be an attractive alternative option. However, its prognostic factors are poorly understood.

METHODS

All patients undergoing valve-in-MAC TMVI from 2013 to 2018 in our center were included. Indication for TMVI relied on the judgment of the local heart team. Patients were followed at 30 days and 1 year.

RESULTS

A total of 34 patients underwent valve-in-MAC TMVI. The mean age was 79 ± 11 years and 73% of patients were women. Their mean EuroSCORE 2 was 8 ± 7%. The transseptal approach was used in 79% of patients and a hybrid transatrial in 29%. Balloon expandable transcatheter heart valves were used in all the patients. Technical success was achieved in 76% of the patients. Thirty-day and 1-year all-cause mortality rates were 14.7% and 32.4%, respectively. The main two causes of 1-year mortality were congestive heart failure (8.8%) and infective endocarditis (5.9%). In multivariate analysis, the only predictor of 1-year mortality was the presence of periprothetic mitral regurgitation grade 2 (HR, 5.69; 95%CI, 1.59-27.88, p = 0.032).

CONCLUSION

Early and mid-term mortality remains high after valve-in-MAC TMVI and seems to be associated with the presence of paravalvular mitral regurgitation. However, whether the latter is a prognostic factor or marker remains to be determined to improve clinical outcomes in this high-risk population.

Reasons for Screen Failure for Transcatheter Mitral Valve Repair and Replacement

Despite an expanding armamentarium of devices, many patients with mitral regurgitation referred for transcatheter mitral valve repair (TMVr) or replacement (TMVR) do not meet strict clinical trial inclusion and exclusion criteria. We sought to understand the rates that patients were excluded from transcatheter mitral valve therapies and reasons why. We retrospectively analyzed the medical charts and correspondence related to patients referred to our tertiary valve center for TMVr or TMVR between June 2016 and September 2019. Patients were screened for eligibility by our structural Heart Team for either TMVr or TMVR. If TMVr or TMVR was not offered, the reason for screen failure was recorded and categorized. Over the 3-year period, 564 patients were referred for TMVr and orTMVR. Out of these, 15.9% were determined to be eligible for, and underwent, surgical repair or replacement. Ninety-two patients (16.3%) underwent TMVr or TMVR. The majority of patients (343 of 564, 60.8%) ultimately did not undergo intervention. The primary reason for exclusion was clinical in 38.5%, issues related to patient preference of care delivery in 38.8%, anatomical in 13.7%, and futility in 9.0%. In contemporary real-world practice, the majority of patients with mitral regurgitation referred for transcatheter therapies are excluded. Clinical trials testing new transcatheter devices should be encouraged to record and report reasons for screen failure and follow these patients to better understand optimal timing of intervention, address challenging anatomies, and, ultimately, improve penetrance of these novel therapies.

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.

Transcatheter mitral valve implantation using a novel system: preclinical results

BACKGROUND

This preclinical study in sheep sought to demonstrate the initial safety and feasibility of a novel transcatheter mitral valve system (Mi-thos valve) composed of a self-expanding frame and a bovine pericardial tissue bioprosthesis.

METHODS

The valve was implanted in 26 sheep using a transapical approach for short- and long-term evaluation. The technical feasibility, safety, durability, and valve function were evaluated during and 6 months after the procedure using intracardiac and transthoracic echocardiography, multisliced computed tomography, histological analysis, and electron microscopy.

RESULTS

The success rate of valve implantation was 100%, and the immediate survival rate after surgery was 84%. Five animals died within 90 min after the development of the prosthetic valve due to an acute left ventricular outflow tract obstruction (n = 2) and sudden intraoperative ventricular fibrillation (n = 3). Twelve animals died within 1 month due to acute left heart dysfunction. Mild (n = 5) and moderate (n = 2) paravalvular leakage occurred in seven animals, and two moderate PVL animals died of chronic heart failure within three months. Multimodality imaging studies of the remaining seven animals showed excellent function and alignment of the valves, with no coronary artery obstruction, no left ventricular outflow tract obstruction, no severe transvalvular gradients and no paravalvular leakage. Macroscopic evaluation demonstrated stable, secure positioning of the valve, with full endothelialization of the valve leaflets without injury to the ventricular or atrial walls. Histological and electron microscopic examinations at six months showed no obvious macro- or microcalcification in the leaflets.

CONCLUSIONS

Preclinical studies indicate that transcatheter implantation of the Mi-thos valve is technically safe and feasible. The durability, functionality, and lack of leaflet calcification were all verified in animal experiments. The information from these preclinical studies will be applied to patient selection criteria and the first-in-human studies.

Relation of Mitral Annulus and Left Atrial Dysfunction to the Severity of Functional Mitral Regurgitation in Patients with Dilated Cardiomyopathy

METHODS

56 patients (58 ± 17 years, 42 men) with DCM and FMR and 52 controls, prospectively enrolled, underwent 3DTTE dedicated for mitral valve (MV), LA, and left ventricle (LV) quantitative analysis.

RESULTS

Patients with FMR vs. controls presented increased MA size and sphericity during the entire systole, whereas MA fractional area change (MAFAC) and MA displacement were decreased (15 ± 5 vs. 28 ± 5%; and 5 ± 3 vs. 10 ± 2 mm, p < 0.001). In patients with moderate/severe FMR, MA diameters correlated with PISA radius, EROA, and regurgitant volume (Rvol), as also did the MA area (with PISA radius, EROA, and Rvol: r = 0.48, r = 0.58, and r = 0.47, p < 0.05). MAFAC correlated inversely with EROA and Rvol (r = -0.32 and r = -0.35, p < 0.05), with both active and total LA emptying fractions and with LV ejection fraction as well. In a stepwise multivariate regression model, decreased MAFAC and increased LA volume independently predicted patients with severe FMR.

CONCLUSIONS

Patients with DCM and FMR have MA geometry remodeling and contractile dysfunction, correlated with the severity of FMR. MA contractile dysfunction correlated with both LA and left LV pumps dysfunctions and predicted patients with severe FMR. Our results provide new insights that might help with better selection of patients for MV transcatheter procedures.

Anterior Leaflet Laceration to Prevent Ventricular Outflow Tract Obstruction During Transcatheter Mitral Valve Replacement

BACKGROUND

Left ventricular outflow tract (LVOT) obstruction is a leading cause of mortality and exclusion from transcatheter mitral valve replacement (TMVR). Intentional laceration of the anterior mitral valve leaflet to prevent LVOT obstruction (LAMPOON) is a transcatheter mimic of surgical chord-sparing leaflet resection.

OBJECTIVES

The purpose of this prospective multicenter trial was to study LAMPOON with transseptal (Edwards Lifesciences, Irvine, California) TMVR in annuloplasty rings or native mitral annular calcification (MAC).

METHODS

Subjects at high or extreme surgical risk and prohibitive risk of LVOT obstruction from TMVR were included. Eligibility was modified midtrial to exclude subjects with threatened LVOT obstruction from a Sapien 3 valve fabric skirt. The primary endpoint was procedure survival with successful LAMPOON, with successful TMVR, without reintervention, and with LVOT gradient <30 mm Hg ("optimal") or <50 mm Hg ("acceptable"). Secondary endpoints included 30-day mortality and major adverse cardiovascular events. There was universal source-data verification and independent monitoring. All endpoints were independently adjudicated. Central laboratories analyzed echocardiogram and CT images.

RESULTS

Between June 2017 and June 2018, 30 subjects were enrolled equally between the MAC and ring arms. LAMPOON traversal and midline laceration was successful in 100%. Procedure survival was 100%, and 30-day survival was 93%. Primary success was achieved in 73%, driven by additional procedures for paravalvular leak (10%) and high-skirt neo-LVOT gradients observed before a protocol amendment. There were no strokes.

CONCLUSIONS

LAMPOON was feasible in native and annuloplasty ring anatomies in patients who were otherwise ineligible for treatment, with acceptable safety. LAMPOON was effective in preventing LVOT obstruction from TMVR. Despite LAMPOON, TMVR using Sapien 3 in annuloplasty rings and MAC still exhibits important limitations. (NHLBI DIR LAMPOON Study: Intentional Laceration of the Anterior Mitral Leaflet to Prevent Left Ventricular Outflow Tract Obstruction During Transcatheter Mitral Valve Implantation; NCT03015194).

Transcatheter Mitral Valve Repair and Replacement: Current Evidence for Intervention and the Role of CT in Preprocedural Planning-A Review for Radiologists and Cardiologists Alike

The mitral valve is a complex structure with a three-dimensional saddle shape annulus. Mitral regurgitation occurs from leaflet coaptation failure that is either primary (a problem with the leaflets) or secondary (chamber dilatation in the setting of cardiomyopathy). There has been an increase in focus on transcatheter mitral valve interventions, for both mitral repair and replacement. These technologies have rapidly developed to provide treatment for a substantial number of patients with severe symptomatic mitral regurgitation who are at too high of a risk to undergo open heart surgery. CT assessment of the mitral valve has developed with equal rapidity, with regard to preprocedural planning for transcatheter therapies. This review will provide an overview of mitral valve anatomy, an update on the current transcatheter repair and replacement therapies, as well as a focused overview of the role of multislice CT in mitral assessment prior to intervention. © RSNA, 2020.

Recent advances in understanding and managing mitral valve disease

Interest in the mitral valve has increased over the past few years with the development of new technologies that allow intervention in patients previously deemed too ill for treatment. This increased attention has resulted in a significant increase in publications on the mitral valve, the majority of which focus on mitral regurgitation and mitral valve surgery/intervention. The focus of this review is on publications in the past few years that offer additional insights into our understanding and management of mitral valve disease and specifically mitral regurgitation. It will discuss mitral valve anatomy, epidemiology of mitral valve disease, changes in the 2017 management guidelines, management of mitral bioprosthetic valves, transcatheter mitral valve procedures and the repair of rheumatic valves.

Percutaneous treatment of mitral valve regurgitation: Where do we stand?

Surgery has been the standard of care for mitral valve diseases to date. In the last fifteen years, due to increased aging of the population, with a great number of patients being high-risk for surgical treatment, transcatheter treatments for mitral valve disease have greatly developed. Further development and expansion of transcatheter treatments are expected. However, some limitations remain, such as efficacy and durability, which impact the widespread use of these devices.