The standard treatment for degenerative MR is mitral valve repair surgery, which can be performed through a median sternotomy or minimally invasive access. Recently, the concept of microinvasive cardiac surgery has emerged, aiming to replicate conventional surgical techniques through smaller incisions on a beating heart without the need for extracorporeal circulation. In this context, transapical neochord (NC) implantation represents an example of microinvasive cardiac surgery, proposed as an option for degenerative MR using the NeoChord DS 1000® device (NeoChord Inc.), CE marked since 2012 and awaiting FDA approval. Currently, two devices are commercially available for this approach: the NeoChord DS 1000® and the Harpoon® (Edwards Lifesciences®), both showing promising results, though mid-term data are scarce. This study aims to evaluate the clinical and echocardiographic outcomes in patients treated with NC over five years.

All patients undergoing NC at the University of Padua’s cardiac surgery department from November 2013 to March 2016 were included in this study. Indications for the procedure were symptomatic severe degenerative MR due to leaflet prolapse or flail. Patients were categorized based on favorable anatomy (FA: isolated P2 prolapse without annular dilation) or unfavorable anatomy (UA: other MR mechanisms) based on the extent and severity of the mitral valve disease in terms of NC transapical repair feasibility. Clinical and echocardiographic evaluations were conducted at 1-, 3-, 6-, and 12-months post-procedure, followed by annual follow-ups. Data were prospectively collected and retrospectively analyzed, with outcomes based on Mitral Valve Academic Research Consortium (MVARC) guidelines. The analysis included 100 consecutive patients (FA: 81%; UA: 19%) with a median age of 66 years and a mean EuroSCORE II of 1.4%. Technical and procedural success rates were 98% and 94%, respectively. Thirty-day mortality was 2%. Repair success rates were 94%, 92%, and 78% at 30 days, 1 year, and 5 years, respectively. The median follow-up duration was 5.1 years. At 5 years, overall survival was 83%, with no significant differences between FA and UA patients. The cumulative incidence of severe MR recurrence at 5 years was 14% in FA patients and 63% in UA patients (p < .001). FA patients showed a lower reintervention rate compared to UA patients (14.7% vs. 43.4%; p < .001).

The authors concluded that transapical NC implantation may be an acceptable option for patients with degenerative mitral valve disease with FA.

COMMENTARY:

Mitral repair surgery for degenerative MR is regarded as one of the most successful interventions in adult acquired heart disease surgery. According to the latest STS data, the average 30-day mortality is only 0.4%, with 75% of patients having a predictive mortality risk below 1.2%. It is one of the few “curatives” cardiac surgeries, with survival comparable to the general population when successful repair is achieved. Additionally, the percentage of practitioners performing this surgery continues to increase, with over 80% of cases opting for mitral repair as the first approach to MR, achieving a 10-year reoperation-free rate of 99.7% at centers of excellence. However, outcomes at referral centers differ from real-world results; data from the STS indicate that 27% of all mitral valve replacements follow an unsuccessful repair attempt, with mitral repair success rates of 80% (compared to 98% in reference centers) and relatively high long-term recurrence rates. In other words, the impressive results from these centers of excellence are a minority and do not reflect real-world practice.

Any successful new surgical technique should aim to improve current outcomes or at least match them without compromising patient recovery. In this study by D’Onofrio et al., 30-day mortality was 2%, while at five years, 16.7% of patients required reoperation and 23.7% experienced severe MR recurrence. While these results are acceptable, they do not yet match the levels reported by centers of excellence for conventional mitral valve repair. However, compared to other large registries, the results are becoming comparable. It is also noteworthy that patients with FA (e.g., P2 prolapse without annular dilation) achieved excellent outcomes, with no differences in MR recurrence or reintervention rates compared to conventional surgery outcomes reported in other major registries.

It is easy to critique new therapies, as was the case in the early days of TAVI. Microinvasive and transcatheter approaches for degenerative MR represent a complex concept with multiple facets. It is well known that most patients with this condition present annular dilation, which is not addressed by neochord or edge-to-edge therapies. Although the Alfieri repair technique without annuloplasty has generally shown limited success and is reserved for exceptional cases, its percutaneous version has been increasingly adopted in structural interventions. Even in randomized trials like REPAIR MR and PRIMARY, it has proven effective in selected patients, with favorable comparisons to surgical mitral repair.

The main challenge is identifying the ideal candidate for this procedure. Data so far suggest two key criteria: first, an absence of annular dilation, optimizing coaptation area; and second, an absence of ventricular dilation, as some patients exhibit reverse remodeling leading to relative NC shortening, potentially causing MR recurrence. Therefore, ideal candidates would be those at an early stage of mitral valve disease, without the aforementioned features. Another relevant question is determining the options available if the initial procedure fails, including the feasibility of repeat surgical repair (and via which approach) or a direct transition to valve replacement. With this innovative surgical technique, significant damage to the mitral leaflets is avoided, as only Gore-Tex neochords are implanted, without the need for devices (as in the case of the mitral clip). Therefore, it remains compatible with alternative approaches, allowing for repeat repair or replacement, including transcatheter mitral valve replacement, if needed in the future.

Transapical percutaneous neochord techniques continue to evolve, with several new devices under development. It is our responsibility to engage with this technology to improve our skills, critically evaluate outcomes demanding repair quality and durability comparable to conventional surgical techniques, and optimize patient selection for each type of approach. TAVI experience has shown that technological evolution is associated with improved clinical outcomes, making microinvasive NC a potential alternative for a select subgroup of carefully chosen patients. Let us remember that the primary advantage of the cardiac surgeon over other specialists is the ability to offer the most appropriate strategy to each patient according to their specific characteristics, whether through conventional, minimally invasive, microinvasive, or even structural intervention approaches.

REFERENCE:

D’Onofrio A, Fiocco A, Nadali M, Mastro F, Aruta P, Lorenzoni G, et al.; Padova Neochord Working Group. Outcomes of transapical mitral valve repair with neochordae implantation. J Thorac Cardiovasc Surg. 2022 Apr 9(22)00387-7. doi: 10.1016/j.jtcvs.2022.02.059.