Currently, valve repair is the surgical treatment of choice for patients with severe mitral regurgitation due to degenerative disease. In practice, two primary repair techniques exist: leaflet preservation, involving artificial neochordae, and leaflet resection, including common procedures such as triangular or quadrangular resections, with or without sliding plasty. After repair, some patients may experience higher mean transvalvular gradients compared to those without mitral valve disease, independent of the chosen repair technique. These elevated gradients may adversely affect long-term hemodynamics, potentially leading to left atrial dilation, which predisposes to atrial fibrillation, or incomplete resolution of pulmonary hypertension, ultimately impacting exercise capacity and quality of life post-surgery.

The CAMRA CardioLink-2 study is a multicenter, double-blind, randomized study that included 104 patients with primary degenerative mitral regurgitation and posterior leaflet prolapse. Patients were randomized to undergo either a leaflet preservation or resection repair. Patients with anterior leaflet prolapse, rheumatic mitral disease, endocarditis, or extensive calcification were excluded. The Carpentier-Edwards Physio II® ring was used for annuloplasty in all repairs, with edge-to-edge repair techniques (central or commissuroplasty) also applied. Logistic regression was used to analyze risk factors associated with residual elevated transvalvular gradients post-repair. At 12-month follow-up, functional outcomes were compared between patients with elevated mitral gradients (≥5 mmHg) and those with gradients <5 mmHg. Elevated mitral gradients were identified in 15 patients (14.4%) without significant differences between repair strategies. Risk factors identified included female gender (p = 0.02), lower preoperative hemoglobin levels (p = 0.01), smaller intercommissural diameters (p = 0.02), and smaller annuloplasty ring sizes (p = 0.001). The ratio between intercommissural diameter and annuloplasty ring size was similar among patients with and without elevated gradients, indicating no deliberate undersizing of the implanted rings, as seen in repairs for ischemic mitral regurgitation. At 12-month follow-up, patients with elevated gradients demonstrated worse NYHA functional classification (p = 0.001), lower peak oxygen saturation during exercise (p = 0.01), lower body weight-walking distance ratio (p = 0.02), and higher fatigue scores on the Borg scale during the six-minute walk test (p = 0.01).

The authors conclude that female gender, smaller mitral anatomy, and lower preoperative hemoglobin levels are associated with higher residual transvalvular gradients following mitral valve repair, correlating with reduced postoperative functional capacity.

COMMENTARY:

Mitral repair techniques should aim to restore the valve’s normal physiology alongside correcting regurgitation. Avoiding elevated transvalvular gradients is essential, and considering identified risk factors in the surgical technique could improve long-term outcomes. Tirone David’s additional commentary in this publication raises points not addressed in the study. While the study compared patients with similar pathology (severe primary mitral regurgitation from posterior leaflet prolapse) randomized to different repair strategies, David notes the study’s lack of differentiation by underlying valvular degeneration etiology. He observes that fibroelastic deficiency patients tend to have thinner, smaller, and more mobile leaflets, while myxomatous degeneration patients often have larger, thicker, and more rigid leaflets. Consequently, small, rigid annuloplasty rings may be better suited for fibroelastic deficiency cases than myxomatous degeneration cases, which might result in higher residual gradients. David suggests using preservation techniques for fibroelastic deficiency and resection techniques for myxomatous degeneration. Additionally, utilizing a single ring type ensures study consistency, reducing residual gradient variability. However, surgical variability in annuloplasty ring types limits the generalizability of these findings to settings employing rings with different dimensions and mechanical properties. Despite statistically significant findings, a larger sample is needed to confirm these results in clinical practice and perform robust subgroup analyses.

In summary, considering fibroelastic or myxomatous deficiency profiles in repair strategy is essential, as smaller annuloplasty rings and/or reduced ring size may lead to higher postoperative gradients. Preoperative optimization and technique adaptation to individual anatomical characteristics are crucial for repair success. Failing to address these factors could exchange mitral insufficiency for residual stenosis, with potentially negative long-term impacts on functional outcomes and patient quality of life.

REFERENCE:

Hibino M, Pandey AK, Chan V, Mazer CD, Rumman R, Dhingra NK, et al. Risk Factors for Postrepair Elevated Mitral Gradient: A Post-hoc Analysis of a Randomized Trial. Ann Thorac Surg. 2023;115(2):437-443. doi: 10.1016/j.athoracsur.2022.05.053.