Figure 1. A: The Myval valve (Meril Life Sciences Pvt. Ltd., India) is a balloon-expandabl...

Figure 1. B: The ‘Navigator’ delivery system consists of an over-the-wire balloon cath...

Figure 1. C: The PythonTM introducer sheath of 14 Fr (Meril Life Sciences Pvt. Ltd., India...

Tabla 1. Baseline characteristics of the population

Tabla 2. Procedure data. Variables expressed as number and percentage (%)

Tabla 3. Endpoints in their hospital evolution according to VARC-3 criteria

Figura 2. Distribution of implanting centers.

Tabla 4. Operators’ opinion regarding the Myval device

Introduction

In recent years, valve diseases have become highly prevalent, a trend exacerbated by the aging population1. Shortly after its emergence, transcatheter aortic valve implantation (TAVI) has solidified its status as an effective and safe solution to this issue, especially for patients whose surgical risk is considered unacceptably high. This advancement has provided new, less invasive treatment options with results comparable, or sometimes even superior, to traditional surgical procedures. The variety of devices developed offers operators the opportunity to choose the most appropriate prosthesis for each type of patient2-4.

In this context, balloon-expandable devices have further expanded the possibilities of percutaneous treatment for valve disease, as they go beyond aortic valve disease, onto pulmonary, tricuspid, and mitral valve disease. By minimizing procedural complications and improving clinical outcomes, these prostheses have proven to be a promising option in the field of interventional cardiology5-7.

It is important to remember that the world’s first TAVI procedures were performed with balloon-expandable devices (Cribier-Edwards THV, Rouen, France), which validated the technique as safe and reproducible, with sustained outcomes over time8. Over the years, the most significant scientific evidence in this field has been generated with balloon-expandable (Sapien XT - Sapien 3, Edwards Lifesciences, Irvine, California) and self-expanding devices (CoreValve - Evolut, Medtronic Inc, Minneapolis, Minnesota)9-12.

In particular, the MyvalTM balloon-expandable prosthesis (Meril Life Sciences Pvt. Ltd., India) shares common features with pre-existing balloon-expandable devices, while also featuring very important distinguishing characteristics. This device is mounted directly on the balloon, is completely removable, and is available in intermediate and extra-large sizes, with a flexible delivery catheter, a stent height shorter than that of other balloon-expandable prostheses, and the possibility of implanting prostheses of all sizes using the same 14-Fr expandable introducer. Additionally, preliminary publications suggest a low pacemaker rate and more favorable hemodynamic behavior13.

In this study, we present the initial experience of the first 300 valve implantations conducted in Argentina with the Myval prosthesis. Until Meril was introduced in the Argentine market, only a few centers used balloon-expandable technology as their preferred choice. This work aims to analyze the clinical outcomes and assess the potential advantages of this prosthesis for the treatment of valve disease. The information obtained in this study will contribute to strengthening the scientific evidence surrounding the efficacy and safety of these percutaneous interventions in the Latin American region.

Objective To analyze the initial experience of the first 300 valve implantations conducted with balloon-expandable valve Myval in Argentina. We will include the hemodynamic and clinical outcomes, as well as a detailed geographic description and the opinions of the operators involved in the procedures.

Materials and methods

Design. This is a prospective multicenter registry.

Study population. We included all consecutive patients undergoing percutaneous valve replacement with the Myval valve in Argentina between September 8, 2021, and September 22, 2023.

All patients were assessed through a thoracic and abdominal aortic CT angiography before they were approved for the intervention with the Myval device. This task was conducted under very strict parameters, as most centers had no prior experience with balloon-expandable devices and proper aortic ring measurement.

All patients provided their consent for the procedure by signing the informed consent form.

Procedure and endpoints

The indication for the procedure, the prosthesis size selection, and the access route were all discussed using a multidisciplinary approach by the local heart team. At each center, procedures for the first five cases were performed by local interventional cardiologists with the mentorship of an expert operator. The procedures were conducted following current technical standards, similar to other devices.

Age, gender and medical history, type of approach, type of anesthesia, and prosthesis size were the analyzed variables. The primary endpoint was procedural success, and secondary endpoints included all-cause mortality, cardiovascular mortality, stroke, moderate or severe paravalvular leak, and new permanent pacemaker implantation during the hospital stay (criteria determined by the Valve Academic Research Consortium-3 [VARC-3])14. Additionally, researchers recorded operator opinions regarding the device, highlighting differences, advantages, and disadvantages compared to other known devices through a semi-structured survey sent to each operator after the procedure.

Device characteristics

The Myval valve (Meril Life Sciences Pvt. Ltd., India) is a balloon-expandable prosthesis that has a nickel-cobalt stent. Three bovine pericardial leaflets that have undergone anti-calcification treatment are mounted on the aforementioned stent, and the device also includes an outer PET sealing skirt in the inflow or landing zone, which reduces the possibility of residual paravalvular leakage (Figure 1A).

There are four standard prosthesis sizes (20, 23, 26, and 29 mm), three intermediate sizes (21.5, 24.5, 27.5 mm), and two extra-large sizes (30.5 and 32 mm), which cover a ring area range between 270 mm² and 840 mm² using the oversizing recommended by the manufacturer. It should be noted that the last five sizes mentioned are exclusive to Myval, without being available in any other device.

Myval prosthesis kit

This device came with a kit for each intervention in all treated patients, consisting of the following supplies:

• Balloon-expandable prosthesis (Figure 1A).

• Navigator release system, with high flexibility and navigability (Figure 1B).

• 14-Fr PythonTM expandable introducer sheath (Meril LifeSciences Pvt. Ltd., India) (Figure 1C).

• MammothTM semi-compliant balloon for predilation (Meril LifeSciences Pvt. Ltd., India).

• Val-de-Crimp crimping device.

The Myval device was guided to the target valve ring using a delivery system consisting of a specially designed over-the-wire high-flexibility balloon catheter: the NavigatorTM (Meril LifeSciences Pvt. Ltd., India), which uses a crimping tool, the Val-de-CrimpTM (Meril LifeSciences Pvt. Ltd., India). This valve is crimped directly onto the balloon of the NavigatorTM delivery system, thus eliminating the need to maneuver or mount the valve onto the balloon in the aorta (Figure 1B). This feature reduces the risk of balloon rupture during the procedure and is also less likely to traumatize the delivery system balloon. Once in position, the valve can be precisely deployed at the target site (in its orthotopic position) through simple inflation, by connecting to a high-pressure inflator at the proximal port while stabilizing the patient’s heart through rapid pacing.

The 14-Fr PythonTM introducer sheath (Meril LifeSciences Pvt. Ltd., India) is specifically designed for the insertion of the Myval device. It is compatible with all valve sizes, from 20 mm to 32 mm. Additionally, this sheath can fully retrieve the device—an exceptional feature—if the operator is unable to cross the aortic ring due to anatomical challenges (Figure 1C). The MammothTM semi-compliant balloon for predilation (Meril LifeSciences Pvt. is included in the kit and available in the following sizes: 14 mm, 16 mm, 18 mm, 20 mm, 23 mm, and 25 mm.

Statistical analysis

Categorical variables are expressed as percentages. Continuous variables with a normal distribution are presented as mean and standard deviation, and, in cases of non-Gaussian distribution, as median and interquartile range. Categorical variables were compared using contingency tables, with Yates’ corrected chi-square test or Fisher’s exact test, as appropriate. The comparison of continuous variables was performed using the t-test or through non-parametric tests (Wilcoxon and Kruskal-Wallis), depending on distribution. The analysis was conducted using the Statistix 7.0 software, and p < 0.05 was considered significant.

Results

The study included the first 300 consecutive patients who underwent percutaneous Myval valve implantation in Argentina from September 8, 2021, to September 22, 2023.

The characteristics of the population can be found in Table 1, where the patient comorbidities and intermediate-to-high cardiovascular risk stand out. Overall, 74.3% of the patients were functional class III, and 10.7% were functional class IV.

Notably, 95% of all implantations were in the aortic valve. Of these, 97.9% were in native valves and, of these, 93.7% were in tricuspid valves and 6.3% in bicuspid valves. Additionally, 2.7% of all implantations were in the tricuspid valve (seven valve-in-valve cases and one valve-in-ring case); 1.3% in the pulmonary valve (all cases with prior stent implantation), and 1% in the mitral valve (one valve-in-valve case, one valve-in-ring case, and one Mac case).

When analyzing aortic valve disease, 98.7% of the procedures were conducted in cases of severe aortic stenosis, and 1.3% in cases of pure aortic regurgitation. Regarding the stenosis cases, the mean aortic valve area, as measured by Doppler echocardiography, was 0.72±0.38 cm² (Table 1).

In 55.3% of the cases, the procedure was performed under deep sedation and local anesthesia, while 44.7% were performed under general anesthesia. In 59.7% of the cases, percutaneous access was used, while 40.3% had surgical access. About 52.3% of all implantations required standard-size valves, 44.3% required intermediate sizes, and 3.3% required extra-large sizes. Predilation was performed in 60% of the cases, while only 18.3% of the procedures required postdilation (Table 2).

In cases of aortic implantation due to stenosis, there was a significant reduction in the peak transvalvular gradient (73±16 vs. 5±3 mmHg; p < 0.001), with no severe aortic regurgitation after the procedure. Conduction disorders were infrequent, with a rate of post-procedural permanent pacemaker implantation of 6.7%—7%, when only considering aortic valve implantations.

Mortality during the procedure (including all procedures) was 0.7% (2 cases): one case due to ventricular perforation caused by an unshaped stiff guidewire and another due to a vascular complication at the access site. In-hospital mortality (including all implantations) was 2.7% (8 patients). The cases were caused by complications secondary to ventricular perforation due to the use of unshaped guidewires, vascular access issues, and cardiogenic shock. In-hospital outcomes and safety endpoints are detailed in Table 3.

The procedures were conducted in 78 centers across 16 of the 24 districts that make up Argentina (Figure 2). The valve was successfully implanted in 99.3% of the patients, and procedural success was achieved in 98.7% of the cases. The operators’ opinions on device characteristics are described in Table 4.

Discussion

The revolution spurred by transcatheter aortic therapy is based on two major advancements: technological device improvements and technique optimization. These result in increasingly effective and less invasive treatment. Recent years have seen the development of multiple devices, facilitating the expansion of both the patient spectrum for this treatment and its scope of application to valves beyond the aortic valve15-20.

To our knowledge, this is the first study to examine the clinical efficacy and early safety of the Myval THV balloon-expandable valve in the Argentine population. Our findings have shown favorable clinical outcomes, particularly regarding the low rate of conduction disorders and the lack of severe residual aortic regurgitation. The primary endpoint, early procedural success, was achieved in 98.7% of patients.

This is a descriptive, prospective, non-randomized series, without a control group and without follow-up beyond in-hospital evolution. However, the population described here reflects the real-world scenario of valve implantation in Argentina, with patients of varying characteristics and complexity. It is worth noting that data collected corresponded to procedures conducted in 78 centers across 16 of the 24 districts that make up the country (66.7%). This is a highly representative sample of the reality for this technique in Argentina, including operator progress and skill, considering that many had no prior experience with balloon-expandable prostheses or were still in the learning curve21.

Since these were consecutive patients, there was no selection bias or other restrictions that could have distorted the experience. We believe that, unlike in other countries, the population undergoing percutaneous implantation in Argentina remains a high-risk or inoperable population. This assertion is based on the age of the treated patients, their EuroSCORE II, their functional class before implantation, and the presence of comorbidities. It is important to highlight that despite the cited limitations, the results found are similar to those reported in major international registries with this prosthesis6, 7, 22, 23. These encouraging clinical findings for Myval could be attributed to its outstanding design features, which facilitate precise positioning and deployment, as well as a size matrix that allows for the treatment of a very high percentage of patients.

When analyzing the size of the valves used, nearly half of the cases required intermediate or extra-large sizes, which could have the advantage of not excessively oversizing or underexpanding a prosthesis to cover the annular area (that is, adding or subtracting more than 2 mL from the nominal inflation value). This could improve the hemodynamic profile and, in turn, reduce complications such as central valve leak, annular rupture, and device embolization, especially when dealing with complex anatomies22-24. Extra-large sizes can, in many cases, be the valve of choice for patients with extremely large aortic rings, or in cases of mitral or tricuspid valve implantation, or non-calcified pure aortic regurgitation15, 18, 25, 26. It is worth noting that during the first year of this experience, the extra-large devices had not yet been approved by the National Administration of Drugs, Food, and Medical Technology (ANMAT), which would explain their low use in the registry.

Moreover, considering that nearly 60% of the cases had a history of coronary artery disease, the Myval design allows for easy new access to the coronary ostium, if needed27.

It should be noted that 5% of the procedures were performed in the tricuspid, mitral, or pulmonary valve. The tricuspid valve implantations were performed on prosthetic valves or rings; pulmonary valve implantations, on native valves with prior stent placement; and mitral valve implantations on prostheses, rings, and native valves, thus demonstrating the device’s versatility15-20. It should be remembered that this device, unlike its balloon-expandable competitors, can be completely retrieved from the body after insertion, which offers a special advantage for mitral or tricuspid procedures, where the likelihood of losing guidewire position is higher18, 19.

When analyzing the in-hospital mortality for the registry, 2.7% (8 patients) is an expected value for this type of procedure, especially considering the previously mentioned high-risk population and the fact that, in most cases, the physicians involved were in the learning curve for the device21. Another noteworthy aspect is the rate of pacemaker implantation after the procedure (20 patients, 7% when considering only aortic valve implantation)28, 29. The values for hemodynamic parameters after the procedure demonstrate the efficacy of this new valve. The aortic transvalvular gradients decreased significantly (73±16 vs. 5±3 mmHg; p < 0.001), with a low need for post-dilation (18.7%) and no severe perivalvular leak, a variable associated with good long-term prognosis8, 30.

Finally, considering all the previously described virtues, operator acceptance of the device was very good (Table 4), not only due to its technical characteristics but also because it is easy to use and its results are easily reproducible.

Limitations

In this multicenter registry, we analyzed the results of the first 300 Myval aortic valve implantations conducted in Argentina, without long-term follow-up. This group of patients, being the first, possibly includes higher rates of complex anatomy, non-aortic valve disease, and large annular area, which are cases that can only be treated with this device. Additionally, endpoint assessment was not centralized but provided by operators at each center. We believe that larger registries with follow-up are necessary to evaluate the efficacy and safety of the device.

Conclusions:

In our initial experience, transcatheter implantation with the Myval prosthesis for the treatment of different types of severe valve disease has been feasible, effective, and safe. This prosthesis has proven to be versatile and has been favorably used in very diverse and highly complex scenarios, with a low need for pacemaker implantation. The intermediate and extra-large sizes allowed for the coverage of annular areas up to 840 mm2, thus constituting the only alternative recommended by manufacturers for such cases. The geographic distribution of implants and operator opinions demonstrate broad acceptance and a satisfactory experience.

Conflicts of interests

Federico Blanco, Juan Pablo De Brahi, and Pablo Lamelas are proctors for Myval (Meril LifeScienses). No conflicts of interest whatsoever for the other authors.

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Initial experience with the Myval ballon-expandable valve in Argentina

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