Current Status of Catheter-based Mitral Valve Replacement

How Would We Treat Our Own Left Ventricular Outflow Tract Obstruction in Transcatheter Mitral Valve Replacement?

This article aims to provide a comprehensive review of the current knowledge on the prevention and treatment of left ventricular outflow tract obstruction (LVOTO) associated with transcatheter mitral valve replacement-a novel and evolving treatment alternative for mitral regurgitation-encompassing both surgical and pharmacological interventions. LVOTO is a potentially catastrophic complication of transcatheter mitral valve replacement. Therefore, identifying patients at high risk for LVOTO and implementing a carefully tailored medical and surgical strategy are essential for optimizing perioperative management and improving patient outcomes.

LAMPOON Technique and Transapical Wire Externalization During Transcatheter Mitral Valve Replacement

A 74-year-old woman with failed mitral surgical repair underwent transcatheter mitral valve-in-ring replacement. Pre-procedural assessment highlighted a substantial risk for valve misalignment and left ventricular outflow obstruction. Electrosurgical laceration of the anterior mitral leaflet to prevent outflow obstruction (LAMPOON) technique and transapical wire externalization for valve deployment were successfully employed to prevent these complications.

The posterior mitral leaflet overhang: A rare yet possible complication of percutaneous mitral valve procedures

The two surgical options for mitral valve regurgitation are replacement and repair, with annuloplasty being the cornerstone of correction. In cases of repair failure, especially in high surgical risk patients, transcatheter mitral valve-in-ring (MViR) procedures represent emerging and challenging options. Among the several complications linked to this treatment, this paper delves into the role that native mitral leaflets may play in precipitating acute bioprosthesis dysfunction in the MViR procedure. The literature extensively covers complications related to the anterior leaflet, including risks such as outflow tract obstruction and residual mitral insufficiency due to interaction between native and prosthetic leaflets. Conversely, complications involving the posterior leaflet are less understood and often overlooked. In this gap in the literature, we present a clinical case highlighting how a redundant native posterior mitral leaflet can unexpectedly lead to acute severe mitral insufficiency by interfering with prosthetic leaflets.

Multimodal preoperative imaging for transcatheter mitral valve replacement in the domestic sheep model

Preclinical in vivo evaluation is an essential step in the progression of new cardiac devices into patient use, with studies predominantly performed in the domestic sheep model. A growing area of interest in cardiac device development is transcatheter mitral valve replacement (TMVR). Clinically, multimodal imaging, or computed tomography (CT) and echocardiography (echo) are used extensively to preoperatively determine mitral valve morphology prior to an intervention, but there is no description on how these modalities can be implemented to support preclinical studies. The purpose of this study is to apply clinically relevant CT and echo acquisition and assessment techniques to a large group of naive research sheep in order to analyze and report modality-related effects on mitral valve dimensional reference intervals in the sheep model. To this end, fifty-five adult domestic sheep underwent preoperative CT and echo exams and resultant images were analyzed using a landmark-based multiplanar measurement protocol and compiled into a master dataset for statistical analysis. We found moderate agreement between CT and echo-derived measurements of the mitral valve in sheep and propose the first clinically-relevant dimensional indices for the sheep's naive mitral valve which can be used to guide future studies evaluating novel TMVR devices. This study is the first of its kind in proposing a reproducible method for detailed examination of the mitral valve in the sheep model using clinically-relevant multimodal imaging. As in patients, CT and echo can reveal accurate native mitral valve dimensions in the sheep prior to preclinical TMVR studies.

Antithrombotic Treatment After Transcatheter Valve Interventions: Current Status and Future Directions

PURPOSE

The optimal antithrombotic strategy after transcatheter valve interventions is a subject of ongoing debate. Although there is evidence from randomized trials in patients undergoing transcatheter aortic valve replacement (TAVR), current evidence on optimal antithrombotic management after transcatheter mitral or tricuspid valve interventions is sparse. This article appraises the current evidence on this topic.

METHODS

This narrative review presents key research findings and guideline recommendations, as well as highlights areas for future research.

FINDINGS

After TAVR, randomized trial evidence suggests that single antiplatelet therapy is reasonable for patients without pre-existing indications for oral anticoagulation (OAC). If there is a concurrent indication for OAC, the addition of antiplatelet therapy increases bleeding risk. Whether direct oral anticoagulants achieve better outcomes than vitamin K antagonists is uncertain in this setting. Although OAC has been shown to reduce subclinical leaflet thrombosis (which may progress to structural valve degeneration), bleeding events are unacceptably high. There is a lack of randomized trial data comparing antithrombotic strategies after transcatheter mitral or tricuspid valve replacement or after mitral or tricuspid transcatheter edge-to-edge repair. Single antiplatelet therapy after mitral or tricuspid transcatheter edge-to-edge repair may be appropriate, whereas at least 3 months of OAC is suggested after transcatheter mitral valve replacement or transcatheter tricuspid valve replacement.

IMPLICATIONS

Randomized studies are warranted to address the knowledge gaps in antithrombotic therapy after transcatheter valve interventions and to optimize outcomes.

1-Year Outcomes Following Transfemoral Transseptal Transcatheter Mitral Valve Replacement: The HighLife TSMVR Feasibility Study

BACKGROUND

A significant number of patients with severe mitral regurgitation (MR) are not suitable for either surgical or transcatheter edge-to-edge repair because of high surgical risk or inappropriate mitral valve anatomy.

OBJECTIVES

The aim of this study was to evaluate the HighLife Trans-Septal Mitral Valve Replacement (TSMVR) system in patients with symptomatic MR and high surgical risk.

METHODS

This prospective, multicenter, nonrandomized feasibility study evaluated the safety and performance of the HighLife TSMVR system in patients with moderate to severe or severe symptomatic MR during 1-year follow-up. Echocardiographic data were assessed at an independent core laboratory.

RESULTS

A total of 30 patients (mean age 75.6 years, 27% women, median Society of Thoracic Surgeons score 5.5%) with severe MR (90% with secondary MR, median left ventricular ejection fraction 43%) were treated at 13 sites. In 27 of the 30 patients, the HighLife TSMVR system was implanted successfully (technical success rate 90%). Device success at 30 days was 83%. After 1 year, 5 patients (17%) had died. None of the patients who underwent implantation required mitral valve reintervention. All patients who underwent implantation had no or trace (78%) or mild (22%) MR, the mean gradient of the HighLife valve was 5.1 mm Hg, and there were no signs of left ventricular outflow tract obstruction (mean gradient 2.0 mm Hg).

CONCLUSIONS

The 1-year results from the HighLife TSMVR feasibility study demonstrate a high technical success rate, excellent valve function, no left ventricular outflow tract obstruction, and no need for mitral valve reintervention. Additional patient outcomes and longer follow-up are needed to confirm these findings. (Expanded Study of the HighLife 28mm Trans-Septal Trans-Catheter Mitral Valve in Patients With Moderate-Severe or Severe Mitral Regurgitation and at High Surgical Risk; NCT04029363).

Mitral Regurgitation in Female Patients: Sex Differences and Disparities

Mitral regurgitation is the most common valvular disease, particularly in older adults. Recent literature has consistently supported that there are significant differences in mitral regurgitation outcomes between male and female patients and that this is likely multifactorial. Numerous sex differences in anatomy and pathophysiology may play a role in delayed diagnoses, referrals, and treatments for female patients. Despite the recognition of these discrepancies in the literature, many guidelines that steer clinical care do not incorporate these factors into society recommendations. Identifying and validating sex-specific diagnostic parameters and increasing the representation of female patients in trials of new mitral regurgitation treatment modalities are key factors in improving outcomes for female patients.

Restructuring the Heart From Failure to Success: Role of Structural Interventions in the Realm of Heart Failure

Heart failure through the spectrum of reduced (HFrEF), mid-range (or mildly reduced or HFmEF), and preserved ejection fraction (HFpEF), continues to plague patients' quality of life through recurrent admissions and high mortality rates. Despite tremendous innovation in medical therapy, patients continue to experience refractory congestive symptoms due to adverse left ventricular remodeling, significant functional mitral regurgitation (FMR), and right-sided failure symptoms due to significant functional tricuspid regurgitation (FTR). As most of these patients are surgically challenging for open cardiac surgery, the past decade has seen the development and evolution of different percutaneous structural interventions targeted at improving FMR and FTR. There is renewed interest in the sphere of left ventricular restorative devices to effect reverse remodeling and thereby improve effective stroke volume and patient outcomes. For patients suffering from HFpEF, there is still a paucity of disease-modifying effective medical therapies, and these patients continue to have recurrent heart failure exacerbations due to impaired left ventricular relaxation and high filling pressures. Structural therapies involving the implantation of inter-atrial shunt devices to decrease left atrial pressure and the development of implantable devices in the pulmonary artery for real-time hemodynamic monitoring would help redefine treatment and outcomes for patients with HFpEF. Lastly, there is pre-clinical data supportive of soft robotic cardiac sleeves that serve to improve cardiac function, can assist contraction as well as relaxation of the heart, and have the potential to be customized for each patient. In this review, we focus on the role of structural interventions in heart failure as it stands in current clinical practice, evaluate the evidence amassed so far, and review promising structural therapies that may transform the future of heart failure management.

Imaging in Transcatheter Mitral Valve Replacement: State-of-Art Review

Mitral regurgitation is the second-most frequent valvular heart disease in Europe and it is associated with high morbidity and mortality. Recognition of MR should encourage the assessment of its etiology, severity, and mechanism in order to determine the best therapeutic approach. Mitral valve surgery constitutes the first-line therapy; however, transcatheter procedures have emerged as an alternative option to treat inoperable and high-risk surgical patients. In patients with suitable anatomy, the transcatheter edge-to-edge mitral leaflet repair is the most frequently applied procedure. In non-reparable patients, transcatheter mitral valve replacement (TMVR) has appeared as a promising intervention. Thus, currently TMVR represents a new treatment option for inoperable or high-risk patients with degenerated or failed bioprosthetic valves (valve-in-valve); failed repairs, (valve-in-ring); inoperable or high-risk patients with native mitral valve anatomy, or those with severe annular calcifications, or valve-in-mitral annular calcification. The patient selection requires multimodality imaging pre-procedural planning to select the best approach and device, study the anatomical landing zone and assess the risk of left ventricular outflow tract obstruction. In the present review, we aimed to highlight the main considerations for TMVR planning from an imaging perspective; before, during, and after TMVR.