Tabla 1. Cardiomyopathy Questionnaire Kansas City score.

Figura 1. (Left) Measurement of the internal diameter of the ring. (Right) Measurement of the extern...

Figura 2. (Left) Left ventricular outflow tract area. (Right) Neo left ventricular outflow tract are...

Figura 3. (Left) Balloon-expandable percutaneous valve implant. (Right) Left ventriculogram after im...

Introduction

Patients who underwent mitral valve replacement with biological prostheses may possibly require reintervention within 10 years. Since the mortality rate for each surgical reintervention is high, the use of percutaneous valves has been explored. While there are percutaneous prostheses specific for the mitral valve under development, percutaneous balloon-expandable devices have been successfully and safely used for challenging cases like the one presented in this article.

The Edwards SAPIEN device is the percutaneous prosthesis most frequently used in the currently available evidence. Meanwhile, the similar Meril Myval prosthesis offers other features that could be favorable for implantation: a wider range of sizes, including extra-large options, and the possibility of using 14-French sheaths. Small studies have taken note of the feasibility and safety of its successful implantation. However, there is no available evidence of valve-in-valve procedures with the FOC Medical-HFS biological prosthesis used in our patient.

Meticulous planning is mandatory for the correct selection of prosthesis size to allow for anchoring on the valve structure, while also avoiding one of the most feared complications: left ventricular outflow tract obstruction.

Clinical case

Our patient was a 64-year-old woman with dyslipidemia, former smoker, with a history of Crohn’s disease, breast cancer requiring surgical and radiotherapy treatment, chronic atrial fibrillation, infectious endocarditis due to Staphylococcus aureus at 21 years old, and at 23 years old due to Streptococcus, with an embolic stroke as a complication. Over the years, she developed moderate mitral regurgitation with prolapse and perforated pseudoaneurysm. She subsequently progressed to symptomatic severe mitral regurgitation, leading to a mitral valve replacement in 2022 using the FOC Medical-HFS bioprosthesis, with preservation of the subvalvular apparatus and tricuspid valve repair with placement of a size 32 hemi-ring. Echocardiograms performed after surgery and during the follow-up confirmed the presence of two perivalvular leaks; one was mild and the other, moderate. One year after surgery, she developed severe prosthetic mitral valve regurgitation due to infectious endocarditis, which required antibiotic treatment. Following treatment, a PET scan confirmed the infectious endocarditis had been successfully resolved. Due to high surgical risk (EuroSCORE II: 8.42) for a new mitral valve replacement through conventional surgery, the chosen alternative was a valve-in-valve procedure using a balloon-expandable percutaneous valve in mitral position with a Myval (Meril Lifescience) device. Up to two weeks prior to the procedure, the patient had a very severe clinical condition as per her assessment through the Kansas City Cardiomyopathy Questionnaire (global score: 8.33), experiencing dyspnea with minimal exertion, rest dyspnea, and inability to walk 50 meters (55 yards) or sleep in supine position (Table 1).

The echocardiogram before the intervention showed preserved biventricular systolic function, sPAP 25 mmHg, severe left atrial dilation (63-mm diameter), 2 perivalvular leaks, and severe mitral regurgitation. The outflow tract area and the internal diameter of the mitral valve ring measured by CT angiography were 542.4 mm2 and 626.7 mm2, respectively (Figures 1 and 2). The procedure was performed under general anesthesia, using a right transfemoral venous access. A Transeptal intra-atrial puncture was performed with transesophageal echocardiographic guide. Due to the need for greater support, after losing position while attempting to advance the device over a Safari guidewire, progress was made using a hydrophilic-coated Cobra catheter through the transeptal puncture, left ventricle, and thoracic aorta. The distal end of the guidewire was captured with a snare from a left transfemoral arterial access and withdrawn through the introducer sheath. Subsequently, the Cobra catheter was replaced with a 7-Fr guidewire catheter. Progress was made through the catheter and, in parallel, with the hydrophilic-coated catheter, a Back Up Meier guidewire, which was also captured with the snare and withdrawn through the left transfemoral access. The hydrophilic-coated catheter and the guidewire catheter were both removed. Under pacing at 150 beats per minute, a Myval (Meril) Ø30.5-mm valve was successfully implanted (Figure 3). The echocardiographic control confirmed normal function of the prosthetic valve, without regurgitation, along the previously existing paravalvular leaks. During the procedure, the patient required vasopressors and experienced bradycardia requiring temporary pacing prior to valve implantation. The patient was extubated in the Hemodynamics OR, progressed favorably without complications, and was discharged 48 hours after the intervention.

At one month of follow-up, the patient showed significant clinical improvement as per assessment through the Cardiomyopathy Questionnaire Kansas City (global score: 77.08). An echocardiogram confirmed good systolic left ventricular function, a well-inserted and functional percutaneous bioprosthesis, and two periprosthetic mild-to-moderate leaks (which were already present before the procedure).

Discussion

The mitral valve has a very complex anatomical and functional structure, which is reflected in its challenging treatment. The high surgical risk of reoperation for conventional valve replacement has led to the development of percutaneous techniques and devices in recent years.

The first key step is to identify the bioprosthesis implanted in the patient. Its type and size will determine the feasibility of a valve-in-valve mitral (ViVM) procedure and the correct size for the percutaneous prosthesis1. Our patient had received a FOC Medical HFS valve during her mitral replacement procedure. That specific valve is not included in the valve-in-valve program developed by the Minneapolis Heart Institute Foundation to help physicians choose a percutaneous prosthesis and its size, which consequently posed a challenge2.

In a systematic review with 2684 patients who underwent ViVM using the Edwards SAPIEN balloon-expandable device, the successful implantation rate was 94-98%; the rate of mortality during the procedure ranged from 1-3%, the rate of stroke was 0-2%, and survival rates at one month and one year were 93-97% and 83-89%, respectively3. In principle, this would be an effective alternative with acceptable outcomes at one year. Other studies have shown similar results compared with redo surgical mitral valve replacement (redo SMVR), with one-year mortality at 11.9% for ViVM vs. 11.3% for redo SMVR4.

Since the mitral valve diameter is typically larger aortic valve diameter, in many cases, the extra-large sizes of the Myval device (30.5 mm and 32 mm) are convenient for these types of implants. While the evidence regarding this new device in ViVM is limited compared with that for the Edwards SAPIEN valve, there is a small registry featuring the Myval balloon valve where successful implantation was reported in all cases, without residual mitral stenosis or left ventricular outflow tract obstruction5. Similar results have been obtained in a more recent study6.

Left ventricular outflow tract (LVOT) obstruction, defined as an increase in the outflow tract gradient of at least 10 mmHg6, is one of the most feared complications for ViVM. Since it is associated with higher surgical mortality, this measurement is important for procedural safety. The reported cutoff points for LVOT area are ≤1.7 cm2 or ≤189 mm2; they are instrumental in determining increased risk of obstruction7, 8.

Percutaneous mitral valve implantation is a therapeutic alternative for this pathology. It can also be considered for patients with surgical mitral ring implantation (valve-in-ring) or severe native mitral valve insufficiency. However, it is still a therapeutic option that needs further exploration. Similarly to percutaneous aortic implants, in these cases durability remains uncertain. Comparative trials with conventional surgery are also pending.

Conclusion

The use of the Myval balloon-expandable percutaneous valve in this case of mitral valve-in-valve implantation has been successful and safe, with good clinical and echocardiographic outcomes at the 30-day follow-up. While more solid evidence with a larger number of cases is needed, this valve prosthesis could be a valid option for these patients.

1. Pirelli L, Hong E, Steffen R, et al. Mitral valve-in-valve and valve-in-ring: tips, tricks, and outcomes. Ann Cardiothorac Surg. 2021 Jan;10(1):96-112.

2. mplsheart.org/valve-in-valve-digital-application.

3. Eleid MF, Rihal CS, Guerrero ME. Transcatheter mitral valve replacement for degenerated mitral bioprostheses: a systematic review. Ann Cardiothorac Surg. 2021;10(5):558-63.

4. Sengupta A, Yazdchi F, Alexis SL, et al. Reoperative Mitral Surgery Versus Transcatheter Mitral Valve Replacement: A Systematic Review. J Am Heart Assoc. 2021;10(6):e019854.

5. Blasco-Turrión S, Serrador-Frutos A, Jose J, et al. Transcatheter Mitral Valve-in-Valve Implantation with the Balloon-Expandable Myval Device. J Clin Med. 2022;11(17):5210. Published 2022 Sep 2.

6. Sankardas MA, Subban V, Kothandam S, et al. Clinical Outcomes Following Transcatheter Mitral Valve-in-Valve Replacement Using a MerilMyval Transcatheter Heart Valve. Heart Lung Circ. Published online January 19, 2024.

7. Yoon SH, Bleiziffer S, Latib A, et al. Predictors of Left Ventricular Outflow Tract Obstruction After Transcatheter Mitral Valve Replacement. JACC Cardiovasc Interv. 2019;12(2):182-93.

8. Lisko J, Kamioka N, Gleason P, et al. Prevention and Treatment of Left Ventricular Outflow Tract Obstruction After Transcatheter Mitral Valve Replacement. IntervCardiol Clin. 2019;8(3):279-85.

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