Percutaneous mitral commissurotomy (PMC) also known as percutaneous mitral balloon commissurotomy (PMBC), percutaneous mitral valvotomy (PMV) or percutaneous mitral balloon valvuloplasty (PMBV) is a transcatheter procedure for the management of mitral stenosis.
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History and etymology
Percutaneous mitral commissurotomy was first described and further developed by the Japanese cardiovascular surgeon Kanji Inoue in the late 1970s and early 1980s 1.
Indications
According to the 2020 ACC/AHA and 2021 ESC/EACTS Guidelines for the Management of Valvular Heart Disease percutaneous mitral commissurotomy (PMC) is recommended with moderate to severe rheumatic mitral stenosis (valve area ≤1.5 cm2) in the following situations 2,3:
- symptomatic patients (NYHA II-IV) – recommended (class 1)
- favorable mitral valve morphology
- contraindications to surgery
- asymptomatic patients – considered reasonable (class 2a)
- pulmonary hypertension (PASP >50mmHg)
- high thromboembolic risk e.g. new-onset atrial fibrillation
A favorable valve morphology implies the following 3:
- mobile a thin mitral valve leaflets
- no calcifications
- no significant subvalvular fusion
Structural requirements
Patients requiring percutaneous mitral commissurotomy should be evaluated by a multidisciplinary heart team and the procedure should be undertaken in a comprehensive heart valve center 3.
Contraindications
Contraindications and unfavorable characteristics of percutaneous mitral commissurotomy (PMC) include 2,3:
- mild mitral stenosis or mitral valve area >1.5 cm2
- moderate to severe mitral regurgitation (>2+)
- left atrial thrombus
- severe bi-commisural calcification
- subvalvular stenosis
- absence of a commissural fusion
- severe aortic or tricuspid valve disease requiring valvular surgery
- concomitant coronary artery disease requiring coronary bypass surgery
Procedure
The procedure requires a collaborative multidisciplinary team of interventional cardiologists, cardiac valve surgeons and cardiac anesthesiologists with appropriate expertise on the subject including valvular heart disease, heart failure electrophysiology and cardiac imaging 2.
Different techniques and approaches have been described. The most commonly used technique by Inoue is conducted under fluoroscopic and transesophageal echocardiographic guidance and includes the following 1,4:
- percutaneous femoral or jugular venous access
- transeptal puncture
- advancement of the balloon catheter across the mitral valve
- inflation of the distal ventricular portion
- inflation of the proximal atrial portion
- inflation of the central portion of the balloon and splitting of the commissures
Complications
Complications of percutaneous mitral commissurotomy include the following:
- severe mitral regurgitation
- residual atrial septal defect
- left ventricular perforation with hemopericardium
- thromboembolic events
- myocardial infarction
Pre-procedural imaging
Pre-procedural imaging includes a qualitative and quantitative assessment of mitral the mitral valve.
Echocardiography
Transthoracic echocardiography serves as an initial diagnostic test to ascertain the indication and to assess the suitability of the mitral valve for percutaneous mitral commissurotomy 3:
- the severity of the mitral stenosis (mitral valve area, transmitral gradient)
- left ventricular and atrial function
- diastolic doming, commissural fusion, leaflet and commissural calcification, subvalvular thickening/chordal fusion
The Wilkinson score is an echocardiographic scoring system to predict the outcome of percutaneous mitral commissurotomy 6.
Transesophageal echocardiography can be used for further assessment 3:
- presence, mechanism and severity of concomitant mitral regurgitation
- exclusion of left atrial thrombus
Post-procedural imaging
Postprocedural imaging involves the evaluation of the success of the procedure that can be done with echocardiography as well as the search for complications.
Radiology report
Pre-procedural evaluation
The radiological report should include a description of the following:
- mitral valve stenosis including mitral valve area
- commisural fusion and calcification
- mitral leaflet mobility
- mitral leaflet calcification and location
- mitral valve thickening
- subvalvular thickening
- associated mitral regurgitation and/or mitral valve prolapse
- associated findings
- aortic or tricuspid valvular heart disease
- concomitant coronary artery disease
Post-procedural evaluation
In a postinterventional setting the radiological report should include a description of the following:
- mitral valve area and possibly transmitral gradients after commissurotomy
- suspected complications
Outcome
The outcome depends on favorable valve morphology and other clinical factors including the degree of heart failure, atrial fibrillation and patient age and the mitral valvular gradient 3.
A successful outcome can be considered as an uncomplicated intervention with a postprocedural mitral valvular area >1.5cm2 without significant mitral regurgitation (>2+) leading to symptomatic relief and a decline in transmitral gradient. This can be expected in about 80-90% of the cases and leads to a gradual decrease in pulmonary artery pressure. Larger preprocedural mitral valve areas, male gender, younger age and a Wilkinson score ≤8 are associated with a better outcome 4.
Factors associated with less good outcomes include the following 3:
- advanced age
- lower transvalvular gradients (<10 mmHg)
- atrial fibrillation
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