Mitral valve repair surgery is the standard treatment for posterior mitral leaflet prolapse in severe mitral regurgitation (MR). For many years, resection was the only surgical solution for this pathology. Later, the teams of Tirone David and Perier described the functional replacement of native chordae with polytetrafluoroethylene sutures as an equally effective alternative, potentially preserving mitral-ventricular continuity more effectively. Since then, there has been a growing preference for chordal replacement techniques, though this approach may not be suitable for all cases.

The purpose of this study was to compare the effect of these two surgical techniques on the postoperative morphology and function of the LV, using, in addition to standard echocardiographic parameters, GLS as a more sensitive and volume-independent echocardiographic parameter for representing LV function.

This study included 125 patients divided into two groups: segmental posterior leaflet resection techniques (resect group, n = 82) and isolated artificial chordal implantation (respect group, n = 43). In all cases, the procedure included annuloplasty. Advanced and standard echocardiographic assessments were performed preoperatively, immediately postoperatively, and during follow-up. Additionally, GLS was measured and adjusted for LV end-diastolic volume to account for significant volume changes.

At baseline, there were no significant differences between groups in LV function as measured by corrected GLS (resect: 1.76% ± 0.58%/10 mL vs respect: 1.70% ± 0.57%/10 mL, p = 0.560). Postoperatively, corrected GLS worsened in both groups but improved significantly during late follow-up, returning to preoperative values (resect: from 1.39% ± 0.49% to 1.71% ± 0.56%/10 mL, p < 0.001, and respect: from 1.30% ± 0.45% to 1.70% ± 0.54%/10 mL, p < 0.001). Mixed model analysis showed no significant effect on corrected LV GLS when comparing the two surgical repair techniques over time (p = 0.943).

COMMENTARY:

Both segmental posterior leaflet resection and artificial chord implantation are surgical techniques that may be chosen based on the size, height, and thickness of the prolapsing posterior leaflet. Patients with fibroelastic deficiency may benefit more from neochords since the leaflet is often smaller, making it advisable to preserve all segments. Conversely, patients with advanced myxomatous degeneration can be treated with some form of resection reliably, as they tend to have larger, bulkier, and thicker posterior leaflets. Currently, many surgeons prefer neochord implantation, reasoning that in the event of future repair failure, re-repair (including the new transapical percutaneous neochord implantation devices) is more feasible if the posterior leaflet remains intact from the initial surgery.

There are various ways to assess a successful mitral repair. The most apparent is through the evaluation of mitral echocardiographic parameters, such as the absence of residual MR, sufficient coaptation length, or confirmation of low transmitral gradients. Another indirect method is the echocardiographic assessment of LV function parameters, such as LVEF, LV GLS, or volume diameter. From the patient’s perspective, the most important way to assess mitral repair is through the analysis of clinical outcomes (symptoms, morbidity, and mortality). One limitation of this study by Wijngaarden et al. is the lack of data on clinical outcomes.

The debate regarding whether one surgical technique is superior to another in terms of durability and mitral-ventricular continuity preservation remains ongoing. Existing evidence for assessing 20-year durability among different repair techniques, mostly from retrospective studies, shows equivalence among them. Other studies, like that of Falk et al., favor the neochord technique when aiming for greater coaptation length, lower gradients, and larger ring sizes.

Assessing LV function after repair is relatively straightforward. The main novelty of this study lies in the evaluation of LV function using corrected GLS rather than merely LV ejection fraction. Although its measurement requires a significant learning curve, GLS corrected provides valuable information on LV function. Used synergistically with other parameters it is particularly in asymptomatic patients. Other useful indicators that could be included in future studies are various biomarkers, LV volume measurements, and other imaging modalities like MRI.

This is a retrospective study with all its inherent limitations. We must wait for additional randomized studies that include more clinical outcomes and better markers to settle the “resect versus respect” debate definitively. Meanwhile, it is time to move forward and accept the obvious: some things are equivalent yet different. We should do what works best in our hands.

REFERENCE:

van Wijngaarden AL, Tomšič A, Mertens BJA, Fortuni F, Delgado V, Bax JJ, Klautz RJM, et al. Mitral valve repair for isolated posterior mitral valve leaflet prolapse: The effect of respect and resect techniques on left ventricular function. J Thorac Cardiovasc Surg. 2022 Nov;164(5):1488-1497.e3. doi: 10.1016/j.jtcvs.2021.02.017.