MViR: Renato valve successfully corrects mitral annuloplasty failure

Miral annuloplasty failure: the challenge of re-treatment in high-risk patients

Mitral repair via annuloplasty is now a common practice, but long-term ring failure exposes patients to a recurrence of mitral regurgitation. For subjects presenting a high surgical risk, a conventional reintervention (redo) is often excluded, making the development of minimally invasive strategies necessary. Transcatheter mitral valve replacement valve-in-ring (MViR) represents a promising solution, although technically complex due to the asymmetrical morphology of annuloplasty rings.

The objective of this study is to report the first clinical use of the Renato valve (Balance Medical) for an MViR procedure. This case involves a 67-year-old female patient suffering from severe left ventricular dysfunction (LVEF 34%) and an STS score of 8.2%. The study aims to demonstrate the safety and efficacy of this new balloon-expandable device in real-world conditions.

The authors test the hypothesis that the structural design of the Renato valve — featuring an exposed metal frame and an internal skirt — allows for minimizing the risks of left ventricular outflow tract (LVOT) obstruction and stabilizing the implant despite the irregular radial forces exerted by the pre-existing surgical ring.

Design and experimental protocol

This study is a clinical case report describing the first implantation in China of a Renato transcatheter valve (Balance Medical Technology) for a mitral valve-in-ring (MViR) procedure. The subject is a 67-year-old female patient presenting with severe mitral regurgitation and left ventricular dysfunction (LVEF 34%) following the failure of a 28 mm semi-rigid annuloplasty ring (Edwards Physio II) implanted five years earlier. Due to an STS score of 8.2%, the patient was deemed ineligible for conventional surgical reintervention.

The preoperative and operative protocol included the following steps:

• Imaging evaluation: Preprocedural CT scan to measure the aorto-mitral angle (40.5°) and simulation of a 27 mm valve implantation (estimated neo-LVOT at 811.5 mm²).
• Choice of approach: The transapical approach was preferred over the transseptal approach (interatrial septum puncture height < 3.5 cm) to ensure better coaxiality.
• Implantation: Positioning of one third of the Renato valve in the atrial position under fluoroscopic and angiographic guidance.

Clinical and hemodynamic follow-up was performed periodically over a period of 42 months (immediate postoperative, 3, 6, 12, 18, 24, 30, 36, and 42 months). Evaluation criteria included transthoracic and transesophageal echocardiography (LVEF, mean pressure gradient, vena contracta, paravalvular leaks), NYHA functional score, and the Kansas City Cardiomyopathy Questionnaire (KCCQ).

Clinical and hemodynamic results

Transapical implantation of the 27 mm Renato valve into the 28 mm Edwards Physio II ring was successfully performed. Immediate post-procedure transoesophageal echocardiography confirmed complete resolution of residual mitral regurgitation (MR), with no left ventricular outflow tract (LVOT) obstruction. A mild-to-moderate paravalvular leak (PVL) was identified (vena contracta = 3 mm), located between 10 and 11 o'clock, attributed to a height misalignment between the prosthesis and the semi-rigid surgical ring.

Long-term follow-up (42 months)

Longitudinal follow-up shows a sustained improvement in cardiac function and the patient's quality of life. The main indicators are summarized in the following table:

Evolution of paravalvular leak and safety

Despite the persistence of moderate PVL observed from the third month, it remained stable without significant progression until the end of the follow-up (42 months), reaching a stage qualified as mild to moderate. The mean pressure gradient remained controlled (5 mmHg at 42 months). No major adverse events were reported during the follow-up period:

• Zero major bleeding episodes.
• Absence of cerebrovascular accident (CVA).
• No rehospitalization for congestive heart failure.

The specific architecture of the Renato valve, characterized by an exposed metallic frame and an internal skirt, allowed for the avoidance of LVOT obstruction despite an initial aorto-mitral angle of 40.5°. The expansion capacity of the stent prevented any patient-prosthesis mismatch (PPM) phenomenon.

A viable alternative to complex surgical redo

The success of this procedure in a high-risk patient (STS 8.2%) confirms that mitral valve-in-ring (MViR) replacement is a concrete therapeutic option when the initial annuloplasty fails. The use of the Renato valve, characterized by an exposed metallic frame and an internal skirt, effectively prevented left ventricular outflow tract (LVOT) obstruction, a major critical risk in this indication.

The obstacle of the ring geometry

The technical highlight is the persistence of a moderate paravalvular leak (PVL), which remained stable during the 42-month follow-up. The study attributes this phenomenon to the configuration of the Edwards Physio II ring (28 mm). Its "D" shape and partial rigidity impose unbalanced radial forces on the transcatheter prosthesis, creating residual gaps. This case emphasizes that adaptation to the non-circular shape of the ring remains the major challenge of MViR compared to Valve-in-Valve, impacting peri-prosthetic sealing.

Implications for clinical practice

Although functional results were notable — with an improvement in NYHA class (IV to II) and KCCQ score (from 67.71 to 83.33) — generalization is limited by the unique nature of this clinical case. The transapical approach, preferred here due to an unfavorable septal puncture height (< 3.5 cm), ensured optimal coaxiality of the device. This technical choice, combined with rigorous 3D CT scan planning, proves decisive in securing the implantation and preventing the risk of valve malposition or displacement.

Summary of results

This case report demonstrates the 4-year durability of a transcatheter mitral valve replacement (MViR) with the Renato valve in a patient presenting with ring failure (LVEF 34%). Despite a stable moderate paravalvular leak, the clinical status significantly improved, with a KCCQ score increasing from 67.71 to 83.33 and a reclassification to NYHA II.

In concrete terms, for the practitioner:

• Surgical alternative: Consider MViR for high-risk patients (STS > 8%) presenting with recurrent mitral regurgitation on a failing annuloplasty ring.
• Device choice: The prosthesis design (exposed metal frame and internal skirt) is critical for preventing left ventricular outflow tract (LVOT) obstruction, a major risk during MViR procedures on asymmetric rings.
• Post-procedure monitoring: Moderate paravalvular leakage can be clinically tolerated over the long term without systematic corrective intervention, provided that heart failure symptoms are controlled (stability observed here over 42 months).

Technical lexicon of the MViR study

MViR (Mitral Valve-in-Ring): Transcatheter intervention procedure consisting of implanting a new heart valve inside a failing surgical annuloplasty ring, thus avoiding open-heart reintervention in high-risk patients.

Renato Valve: New expandable balloon valvular device (Balance Medical Technology) used in this clinical case, featuring an exposed metal frame and an internal skirt specifically designed to prevent left ventricular outflow tract obstruction.

LVOT (Left Ventricular Outflow Tract) obstruction: A major risk during transcatheter mitral valve replacement, where the prosthesis or the native mitral leaflet blocks the left ventricular outflow; evaluated here by CT scan and simulation (estimated neo-LVOT at 811.5 mm²).

STS Score (Society of Thoracic Surgeons): Risk scoring system used to predict surgical mortality and morbidity; a score of 8.2% here justified the choice of a percutaneous approach rather than redo surgery.

PVL (Paravalvular Leak): Periprosthetic leak or regurgitation occurring between the annuloplasty ring and the implanted valve, often caused by the shape asymmetry between the D-shaped ring (Physio II) and the circular prosthesis.

Transapical approach: Surgical access technique through the apex of the left ventricle, selected in this study to facilitate catheter delivery and ensure superior coaxiality compared to the transseptal access.

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