How Much Mitral Valve Can Be Resected?
Up to one full scallop (typically P2) of the posterior mitral valve leaflet can be safely resected during repair, though the exact percentage depends on leaflet morphology and the surgeon's ability to reconstruct adequate coaptation surface—generally, resection should preserve sufficient leaflet tissue to achieve 5-8mm of coaptation height.
Guideline-Based Approach to Leaflet Resection
The 2020 ACC/AHA guidelines 1 outline specific resection techniques based on pathology:
Posterior Leaflet Resection Techniques
Quadrangular resection with annuloplasty ring: Used for isolated posterior leaflet prolapse in fibroelastic deficiency or forme fruste diffuse myxomatous disease. May also be applied to isolated anterior leaflet prolapse 1
Focal triangular resection with annuloplasty ring: Reserved for focal leaflet flail of the posterior or commissural leaflet, rarely for focal anterior leaflet defects 1
Sliding leaflet valvuloplasty with annuloplasty ring: Used when more extensive posterior leaflet resection is needed, particularly in forme fruste diffuse posterior leaflet disease or bileaflet prolapse with excess posterior leaflet 1
Key Surgical Principles
The amount of resectable tissue is not defined by a fixed percentage but rather by:
- Preservation of coaptation surface: Must maintain adequate leaflet tissue to achieve proper coaptation (typically 5-8mm)
- Leaflet mobility: Excessive resection creates tension and restricts motion
- Avoidance of systolic anterior motion (SAM): Particularly important when basal septal hypertrophy is present 1
Contemporary Evidence on Resection vs. Preservation
Recent high-quality research provides important context:
The 2020 CAMRA CardioLink-2 randomized controlled trial 2 directly compared leaflet resection versus preservation in 104 patients, finding no difference in transmitral gradients at peak exercise (9.1±5.2 mm Hg vs 8.3±3.3 mm Hg, p=0.43) at 12 months, dispelling concerns about functional mitral stenosis from resection.
However, two 2025 studies suggest resection may offer superior durability:
A large cohort study 3 of 639 patients (median follow-up 97.3 months) found neochordae implantation had higher MR recurrence compared to leaflet resection (16.1% vs 7.0% at 5 years, p<0.001), though clinical outcomes and pressure gradients were similar
Another 2025 study 4 with propensity-matched analysis showed the neochord group had greater cumulative incidence of reoperative MV surgery (8.0% vs 0.9% at 5 years, p=0.01)
Clinical Decision Algorithm
For single-segment posterior leaflet prolapse (P2):
- Resection is the gold standard with excellent long-term durability 1, 3, 4
- Can safely resect the entire prolapsing segment if adequate tissue remains for reconstruction
For anterior leaflet or bileaflet prolapse:
- Resection becomes more technically challenging 1
- Consider leaflet preservation techniques or referral to high-volume centers
- Both approaches yield similar outcomes when performed by experienced surgeons 5
For extensive/diffuse disease (Barlow's):
- Sliding leaflet valvuloplasty allows more extensive resection while maintaining coaptation 1
- Requires high surgical expertise
Critical Pitfalls to Avoid
- Excessive resection: Creates tension, restricts leaflet motion, and risks SAM
- Inadequate annuloplasty: Resection without proper annular support increases failure risk
- Residual MR: The most important predictor of long-term failure is moderate or greater residual MR at index operation 1
- Wrong patient selection: Patients with calcified annulus, prior endocarditis, or complex anatomy may be better served by preservation techniques or replacement
Quality of Evidence Considerations
While the randomized trial 2 showed equivalent short-term outcomes between techniques, the most recent and highest quality long-term data 3, 4 from 2025 favor resection for durability, particularly for posterior leaflet pathology. The 2026 studies 5, 6 suggest both techniques are acceptable when individualized to anatomy, but the weight of evidence supports resection as the more durable approach for standard posterior leaflet prolapse.