Mitral Repair: When the Resect vs Respect Duel Delivers its Verdict

Left ventricular remodeling after MVr: the "Resect" approach vs. "Respect"

Mitral valve repair (MVr) is not limited to correcting a leak; its primary goal is to initiate left ventricular (LV) reverse remodeling, an essential physiological process for reducing dilated ventricular diameters and volumes. However, uncertainty remains regarding the choice of the optimal surgical strategy: does tissue leaflet resection (Resect technique) offer superior morphological advantages compared to leaflet preservation using neo-chordae (Respect technique)?

This study, derived from a sub-analysis of the UK Mini Mitral Trial randomised trial, focuses exclusively on patients with isolated posterior leaflet prolapse. The primary objective is to compare the impact of these two techniques on LV remodelling kinetics in the short and medium term. The researchers tested the hypothesis of a performance difference between these approaches by measuring the evolution of the indexed LV end-systolic diameter (ILVESD) via transthoracic echocardiography at 12 and 52 postoperative weeks, to determine whether one of the two methods promotes a more pronounced recovery of ventricular function and geometry.

A subgroup from the UK Mini Mitral trial

This study constitutes a sub-analysis of the UK Mini Mitral Trial randomized trial, which initially included 330 patients to compare mini-thoracotomy to median sternotomy. The researchers isolated a cohort of 175 patients specifically presenting with isolated posterior leaflet prolapse.

• Resect Group (n = 36): Patients who underwent leaflet resection.
• Respect Group (n = 139): Patients who benefited from a leaflet preservation technique.

An annuloplasty was performed in almost all subjects (all except one). The clinical and imaging follow-up protocol was standardized at three key stages: preoperatively, at 12 weeks, and then at 52 weeks after the procedure.

Measurement precision was guaranteed by a centralized analysis of all transthoracic echocardiograms (TTE) via a core laboratory. The primary endpoint was the change in indexed left ventricular end-systolic diameter (iLVESD). Data were processed using linear mixed-effects models to compare longitudinal changes in indexed ventricular diameters and volumes, as well as the severity of recurrent mitral regurgitation between the two surgical approaches.

Results: A marked clinical equivalence between Resect and Respect

Data analysis from the UK Mini Mitral trial demonstrates a lack of statistical superiority of one technique over the other regarding left ventricular (LV) reverse remodelling. Almost all patients (except one) underwent annuloplasty in conjunction with the repair.

Ventricular remodeling and echocardiographic parameters

The primary endpoint, the change in indexed LV end-systolic diameter (ILVESD), shows a significant improvement in both groups at 52 weeks. The overall mean reduction from baseline is -5.6% (p < 0.001). However, the direct comparison between the Resect and Respect groups reveals no significant difference (p = 0.24).

Ventricular function kinetics

The study highlights a distinct temporal dynamic according to the phases of the cardiac cycle:

• Diastolic phase: Indexed end-diastolic volumes and diameters showed a constant and significant decrease from the 12th week, continuing up to 52 weeks.
• Systolic phase: Conversely, LV end-systolic volumes and diameters showed a transient increase at 12 weeks post-surgery, before beginning a significant reduction at 52 weeks.

In terms of surgical safety and efficacy, the severity of mitral regurgitation recurrence at one year remained comparable between the two techniques (p = 0.31), confirming that the choice between leaflet resection and preservation does not impact the stability of the repair in the medium term in this cohort.

Clinical analysis and remodeling kinetics

The results of this sub-analysis of the UK Mini Mitral trial settle a persistent technical debate: the choice between valve resection (Resect) and preservation (Respect) does not significantly influence left ventricular (LV) reverse remodelling. Both approaches achieve a similar reduction in indexed left ventricular end-systolic diameter (iLVESD), with an average improvement of 5.6% at one year. Notably for postoperative follow-up, the study highlights a transition phase. At 12 weeks, end-systolic volumes and diameters temporarily increase before significantly receding at 52 weeks. This observation suggests a progressive myocardial adaptation to the new haemodynamic load, regardless of the repair technique used.

Limitations and perspective

Although the study demonstrates equivalence at 52 weeks, the group asymmetry (36 patients in the Resect group versus 139 in the Respect group) reflects a current trend toward valve preservation, but could limit the statistical power to detect subtle differences. Furthermore, while the lack of difference in mitral regurgitation recurrence (p = 0.31) is reassuring, the one-year follow-up remains short for evaluating the long-term structural durability of each technique. These data are nevertheless consistent with the literature suggesting that the success of annuloplasty, performed in almost all patients in the study, remains the pillar of repair stability.

Implications for practice

These findings offer technical freedom to the surgeon. As long as the anatomy allows for effective repair with an absence of residual leakage, the choice of method can rely on the practitioner's specific expertise without fear of altering the functional recovery of the left ventricle.

Summary of results

This study demonstrates that the Resect and Respect techniques are clinically equivalent in inducing reverse left ventricular remodeling, with a mean reduction in indexed end-systolic diameter of 5.6% at one year (p < 0.001). No significant difference was observed between the two approaches regarding the recurrence of mitral regurgitation (p = 0.31) or the improvement in end-diastolic volumes.

In concrete terms, for the practitioner:

• Technical freedom: The choice between leaflet resection or neochordae can be based on your surgical preference or the valvular anatomy, as the functional benefits at 52 weeks are strictly identical.
• Follow-up interpretation: Do not overreact to a transient increase in end-systolic volumes observed at 12 weeks; significant reverse remodeling is a slower process that stabilizes between the 3rd and 12th post-operative month.
• Standardisation: The comparable efficacy of both methods confirms that the quality of the overall repair, including annuloplasty, prevails over the choice of the specific technique for treating the posterior leaflet.

Technical lexicon of the study

LV reverse remodelling: Process of restoring the geometry and normal function of the left ventricle after correction of a volume overload, characterized here by a significant reduction in ventricular diameters and volumes post-surgery.

"Resect" technique (leaflet resection): Surgical approach for mitral repair consisting of the resection of the prolapsed section of the valve leaflet to restore optimal coaptation.

"Respect" technique (leaflet preservation): Mitral repair strategy favoring the preservation of the entire valvular tissue, generally using synthetic neo-chordae to correct prolapse.

ILVESD (indexed LV end-systolic diameter): Left ventricular end-systolic diameter indexed to body surface area. This is the primary parameter used in this study to evaluate the effectiveness of ventricular remodeling.

Annuloplasty: Surgical procedure consisting of implanting a prosthetic ring to stabilize and reshape the mitral annulus, performed in almost all patients in this cohort.

Linear mixed-effects models: Statistical methodology used to compare longitudinal changes in echocardiographic measurements at 12 and 52 weeks, accounting for intra-individual variability.

Posterior leaflet prolapse: Pathology characterized by the displacement of a portion of the posterior mitral leaflet into the left atrium, constituting the anatomical inclusion criterion for this sub-analysis.

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