Mitral stenosis surgery

Mitral stenosis surgery
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Sudarshan Srivats, M.D., M.P.H.[2] Mohammed A. Sbeih, M.D. [3]

Overview

Mitral valve surgery is an established therapy for rheumatic mitral stenosis (MS) and the treatment of choice when percutaneous mitral balloon valvotomy (PMBC) is contraindicated or unlikely to succeed. Surgical options are open commissurotomy (a valve-preserving repair performed under direct vision), mitral valve repair with concomitant procedures, and mitral valve replacement (MVR) with a mechanical or bioprosthetic prosthesis. Because rheumatic MS progresses slowly over decades, surgery is generally deferred until the patient has severe limiting symptoms (NYHA class III–IV), particularly when repair is contemplated. Valve replacement is reserved for patients in whom neither PMBC nor a valve-preserving operation is feasible — typically those with heavy calcification, extensive subvalvular fibrosis with leaflet tethering, or significant concomitant mitral regurgitation (MR). Choice of prosthesis, management of concomitant tricuspid disease, and surgical left atrial appendage (LAA) management are individualized through a Heart Team and shared decision-making.

Indications for Surgery

The decision between PMBC and surgery, and the timing of intervention, rests on symptoms, valve and subvalvular anatomy, concomitant lesions, surgical risk, and local expertise. Surgery is favored when PMBC is contraindicated or when the valve cannot be adequately opened percutaneously.

2020 ACC/AHA Recommendation

Recommendation	COR	LOE
In severely symptomatic patients (NYHA III–IV) with severe rheumatic MS (MVA ≤1.5 cm², Stage D) who 1) are not candidates for PMBC, 2) have failed prior PMBC, 3) require other cardiac procedures, or 4) do not have access to PMBC, mitral valve surgery (repair, commissurotomy, or valve replacement) is indicated.	I	B-NR

Mitral valve replacement is regarded as an option only when no valve-preserving option exists and the patient has severe limiting symptoms. The 2020 guideline does not carry forward the earlier Class IIa recommendation for MVR in severe MS with severe pulmonary hypertension (PASP >60 mm Hg) and NYHA I–II symptoms, nor the Class IIb recommendation for MV surgery with LAA excision after recurrent embolic events; these appear in the retained 2008 block below.

The 2020 guideline addresses concomitant mitral surgery in its general surgical-considerations section rather than as a graded rheumatic-MS recommendation, noting that concomitant procedures may be appropriate at the time of intervention for valvular heart disease to optimize long-term outcomes or obviate future reoperation, weighed against added cross-clamp/bypass time and periprocedural risk. The specific concomitant-surgery recommendations below are retained from the 2014 AHA/ACC guideline and were not carried forward as discrete graded recommendations in 2020:

Recommendation (2014 AHA/ACC)	COR	LOE
Concomitant mitral valve surgery is indicated for patients with severe MS (MVA ≤1.5 cm², Stage C or D) undergoing other cardiac surgery.	I	C
Concomitant mitral valve surgery may be considered for patients with moderate MS (MVA 1.6–2.0 cm²) undergoing other cardiac surgery.	IIb	C

2025 ESC/EACTS Framework

For patients in whom PMC is contraindicated, surgical MV repair or (more commonly) replacement is the recommended alternative. Contraindications to PMC that direct patients toward surgery include:

• MVA >1.5 cm² (not clinically severe)
• LA or LA appendage thrombus
• More than mild MR
• Severe or bicommissural calcification
• Absence of commissural fusion
• Severe concomitant aortic valve disease, or severe combined tricuspid stenosis and regurgitation requiring surgery
• Concomitant coronary artery disease requiring bypass surgery

Surgery is preferred over PMC in patients with severe MS and severe aortic valve disease (unless surgical risk is high) and, in non–high-risk patients, when concomitant severe TR requires repair. Both guidelines concur: PMC for symptomatic severe MS with favorable anatomy, and surgery when PMC is anatomically unsuitable.

Preoperative Evaluation

• Comprehensive imaging: TTE (and TEE when needed) to define MVA, gradient, subvalvular apparatus, calcification, MR severity, concomitant valve disease, LA/LAA thrombus, and pulmonary artery pressure.
• Coronary assessment: coronary angiography (or CT coronary angiography in lower-probability patients) before surgery in patients with suspected or at-risk coronary artery disease; concomitant CABG is performed when indicated and adds little incremental mortality to the valve procedure.
• Pulmonary hemodynamics: preoperative pulmonary hypertension predicts poorer long-term survival and postoperative RV dysfunction/TR; some patients have fixed pulmonary vascular disease that does not fully reverse after relief of MS.
• Rhythm and TR assessment: document AF and grade TR, as both influence the operative plan (concomitant tricuspid repair, surgical AF ablation, LAA management).

Surgical Options

Open Commissurotomy (Valve-Preserving Repair)

Performed via median sternotomy on cardiopulmonary bypass, open commissurotomy allows direct-vision splitting of fused commissures, debridement of calcium, splitting of fused chordae/papillary muscles, annuloplasty, and removal of LA thrombus. It is the preferred surgical approach when anatomy is favorable. In a contemporary series, MVA increased from ~0.9 cm² preoperatively to ~1.6 cm² at 15 years with a durable fall in transmitral gradient. Long-term results are similar to balloon valvuloplasty overall and are consistently superior in patients with a Wilkins score >8. Closed commissurotomy — performed on the beating heart without direct visualization — is now of historical interest in high-income countries and is not the preferred approach when open surgery is available.

Mitral Valve Repair

Rheumatic mitral repair has become more reproducible with techniques including commissurotomy, leaflet mobilization, chordal procedures (e.g., artificial chordae), and annuloplasty; feasibility is reported at 75%–80% in experienced hands. Repair preserves ventricular function, avoids a prosthesis, and eliminates obligatory lifelong anticoagulation — advantages of particular importance in young patients, women of reproductive age, and low-resource settings where anticoagulation monitoring and adherence are difficult. Durability of rheumatic repair depends on adherence to secondary penicillin prophylaxis. Prior PMC does not reduce repairability but is an independent predictor of reoperation after repair.

Propensity-matched comparative data favor repair when feasible:

• In 1,731 rheumatic MV surgery patients, repair yielded comparable survival but fewer valve-related complications than replacement, driven by fewer hemorrhagic events, with comparable reoperation.
• In 1,644 rheumatic patients (529 matched pairs), repair was associated with lower early and overall mortality and fewer valve-related complications, with reoperation rates comparable to replacement.

Mitral Valve Replacement

MVR is indicated when the valve cannot be repaired — heavy leaflet/annular calcification, extensive subvalvular fibrosis with leaflet tethering, or significant mixed MS/MR not amenable to repair. Preservation of the subvalvular apparatus during replacement helps maintain LV geometry and function. Global survival and freedom from prosthetic complications are lower after replacement than repair, reflecting thromboembolism/bleeding with mechanical valves and structural deterioration of bioprostheses.

Prosthesis Selection: Mechanical vs. Bioprosthetic

Prosthesis choice balances structural valve deterioration (favoring mechanical in younger patients) against anticoagulation-related bleeding and thromboembolic risk (favoring bioprosthetic in older patients), and must incorporate patient preference and access to INR monitoring.

Factor	Favors mechanical	Favors bioprosthetic
Age (ACC/AHA)	<50 y	>65 y (shared decision ages 50–65)
Age (ESC/EACTS, mitral position)	<65 y	>70 y
Anticoagulation	Low bleeding risk; reliable INR access; other indication for OAC (e.g., AF)	High bleeding risk; poor compliance / limited INR access
Reintervention	Wishes to avoid reoperation	Accepts future reintervention; access to valve-in-valve options
Durability	Lower structural deterioration	Bioprosthetic durability rises with age at implantation

Expected bioprosthetic mitral durability increases with age at implantation (longer freedom from structural deterioration in older recipients), which underlies the age-based prosthesis thresholds. Between the age thresholds, prosthesis type is a shared decision. A mechanical mitral valve requires a target INR of 2.5–3.5 (ESC: target 3.0), higher than for a current-generation mechanical aortic valve (target 2.5), reflecting greater thromboembolic risk in the mitral position; DOACs are contraindicated in mechanical valves. For the On-X mechanical mitral valve, PROACT Mitral did not establish noninferiority of a lower INR target (2.0–2.5), so the standard 2.5–3.5 target still applies. Emerging data suggest predicted operative mortality should modify prosthesis choice alongside age, with a mechanical survival benefit reported up to ~70 years in patients with low predicted operative risk.

Concomitant Procedures

• Tricuspid valve: moderate-to-severe TR is common in chronic rheumatic mitral disease and frequently warrants concomitant tricuspid repair; patients with significant TR may have better outcomes with a surgical approach that addresses both valves.
• Surgical LAA management: in patients with AF undergoing cardiac surgery, concomitant surgical LAA occlusion/exclusion reduces stroke or systemic embolism when added to oral anticoagulation. In LAAOS III, LAA occlusion reduced stroke/systemic embolism over a mean 3.8 years without increased heart failure or major bleeding, and this benefit was additive to anticoagulation. Anticoagulation should generally be continued after LAA exclusion; discontinuation is an individualized Heart Team decision contingent on confirmed complete closure. Benefit in patients without preoperative AF is unproven.
• Surgical AF ablation: a Cox-maze procedure may be performed concomitantly and is considered complete only with LAA obliteration.

Minimally Invasive and Robotic Approaches

Mini-thoracotomy, endoscopic, and robotically assisted mitral surgery are alternatives to full sternotomy in appropriately selected patients, offering smaller incisions and reduced recovery time; suitability depends on anatomy, calcification, concomitant procedures, and institutional expertise.

Outcomes and Prognosis

• Open commissurotomy and MVR yield comparable 20-year composite outcomes in matched severe-MS cohorts, but commissurotomy is associated with substantially less major bleeding and essentially no prosthetic endocarditis; reoperation trends higher after commissurotomy.
• Rheumatic MV repair is associated with comparable or superior survival and fewer valve-related complications versus replacement in well-selected patients, with reoperation rates that are not significantly different.
• Surgical commissurotomy at expert centers may achieve better long-term outcomes than PMBC, and outcomes are superior to balloon therapy when the Wilkins score is >8.
• Restenosis after prior surgical commissurotomy or PMC most often requires surgical replacement, though redo PMC is reasonable in selected patients whose predominant mechanism is commissural refusion.
• AF may persist or recur after successful intervention; rhythm surveillance and anticoagulation for AF remain important during follow-up.

Complications

• General surgical: bleeding, venous thromboembolism, infection, atelectasis/respiratory complications, and adverse anesthetic reactions.
• Open-heart–specific: perioperative myocardial infarction, stroke, arrhythmias (including AV block requiring pacing), sternal wound infection, post-pericardiotomy syndrome, and acute kidney injury.
• Prosthesis-related: structural valve deterioration (bioprostheses), valve thrombosis or pannus, prosthetic obstruction, thromboembolism, anticoagulation-related bleeding, prosthetic valve endocarditis, paravalvular leak, and hemolytic anemia.

2008 and Incorporated 2006 ACC/AHA Guidelines for the Management of Patients with Valvular Heart Disease (DO NOT EDIT)

Surgery Indications (DO NOT EDIT)

Class I

"1. Mitral valve surgery (repair if possible) is indicated in patients with symptomatic (NYHA functional class III-IV) moderate or severe mitral stenosis when 1) percutaneous mitral balloon valvotomy is unavailable, 2) percutaneous mitral balloon valvotomy is contraindicated because of left atrial thrombus despite anticoagulation or because concomitant moderate to severe mitral regurgitation is present, or 3) the valve morphology is not favorable for percutaneous mitral balloon valvotomy in a patient with acceptable operative risk. (Level of Evidence: B) "

"2. Symptomatic patients with moderate to severe mitral stenosis who also have moderate to severe mitral regurgitation should receive mitral valve replacement, unless valve repair is possible at the time of surgery. (Level of Evidence: C) "

Class III

"1. Mitral valve repair for mitral stenosis is not indicated for patients with mild mitral stenosis. (Level of Evidence: C) "

"2. Closed commissurotomy should not be performed in patients undergoing mitral valve repair; open commissurotomy is the preferred approach. (Level of Evidence: C) "

Class IIa

"1. Mitral valve replacement is reasonable for patients with severe mitral stenosis and severe pulmonary hypertension (pulmonary artery systolic pressure greater than 60 mm Hg) with NYHA functional class I–II symptoms who are not considered candidates for percutaneous mitral balloon valvotomy or surgical mitral valve repair. (Level of Evidence: C) "

Class IIb

"1. Mitral valve repair may be considered for asymptomatic patients with moderate or severe mitral stenosis who have had recurrent embolic events while receiving adequate anticoagulation and who have valve morphology favorable for repair. (Level of Evidence: C) "