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7 Mitral stenosis

Aetiology of mitral stenosis is mostly rheumatic or degenerative. Rheumatic fever is the most common cause of mitral stenosis worldwide. Its prevalence has greatly decreased in industrialized countries, but it remains a significant healthcare problem in developing countries and affects young patients.2,267,358 Degenerative mitral stenosis related to MAC is a distinct pathology and its prevalence significantly increases with age.359,360 Both types of mitral stenosis are more frequent in females.361 In rare cases, mitral stenosis due to valve rigidity but without commissural fusion, may be related to chest radiation, carcinoid heart disease, or inherited metabolic diseases.

7.1 Rheumatic mitral stenosis

7.1.1 Evaluation Clinically significant mitral stenosis is defined by a mitral valve area (MVA) <_1.5 cm2. Commissural fusion with thickening of the posterior leaflet is the most important mechanism of stenosis. Echocardiography is the preferred method for diagnosis, assessment of severity, and haemodynamic consequences of mitral stenosis. Valve area using 2D planimetry is the reference measurement of mitral stenosis severity, whereas mean transvalvular gradient and pulmonary pressures reflect its consequences and have a prognostic role.362 3D-TTE planimetry may have an additional diagnostic value. TTE usually provides sufficient information for routine management. Scoring systems have been developed to help assess suitability for percutaneous mitral commissurotomy (PMC; Supplementary Table 8),363365 TOE should be performed to exclude LA thrombus before PMC or after an embolic episode, and to obtain detailed information on mitral anatomy (commissural zones and subvalvular apparatus) before intervention when TTE is suboptimal. Stress testing is indicated in patients with no symptoms or symptoms equivocal or discordant with the severity of mitral stenosis. Exercise echocardiography may provide objective information by assessing changes in mitral gradient and pulmonary artery pressure and is superior to DSE. Echocardiography plays an important role in the periprocedural monitoring of PMC and follow-up.

7.1.2 Indications for intervention The type of treatment (PMC or surgery), as well as its timing, should be decided based on clinical characteristics, anatomy of valve and subvalvular apparatus, and local expertise.366369 In general, indication for intervention should be limited to patients with clinically significant (moderate-to-severe) rheumatic mitral stenosis (valve area <_1.5 cm2) in whom PMC has had a significant impact on its management. In Western countries where incidence of rheumatic fever and number of PMC is low, this treatment should be restricted to expert operators in specialized centres to improve safety and procedural success rate.366 Efforts should be made to increase availability of PMC in developing countries where access to treatment is limited due to economic reasons.267 PMC should be considered as an initial treatment for selected patients with mild to moderate calcification or impaired subvalvular apparatus, but who have otherwise favourable clinical characteristics.360 The management of clinically significant rheumatic mitral stenosis is summarized in Figure 7 and the indications and contraindications for PMC are provided in the table of recommendations below, and Table 8. Recommendations on indications for percutaneous mitral commissurotomy and mitral valve surgery in clinically significant (moderate or severe) mitral stenosis (valve area 1.5 cm2)

Recommendations Classa Levelb

PMC is recommended in symptomatic patients without unfavourable characteristicsc for PMC.360,363365,367 I B PMC is recommended in any symptomatic patients with a contraindication or a high risk for surgery. I C Mitral valve surgery is recommended in symptomatic patients who are not suitable for PMC in the absence of futility. I C PMC should be considered as initial treatment in symptomatic patients with suboptimal anatomy but no unfavourable clinical characteristics for PMC.c IIa C PMC should be considered in asymptomatic patients without unfavourable clinical and ana-

tomical characteristicsc for PMC and: • High thromboembolic risk (history of systemic

embolism, dense spontaneous contrast in the

LA, new-onset or paroxysmal AF), and/or • High risk of haemodynamic decompensation

(systolic pulmonary pressure >50mmHg at rest, need for major NCS, desire for pregnancy). IIa C

AF = atrial fibrillation; LA = left atrium/left atrial; MVA = mitral valve area; NCS = non-cardiac surgery; PMC = percutaneous mitral commissurotomy. aClass of recommendation. bLevel of evidence. cUnfavourable characteristics for PMC can be defined by the presence of several of the following characteristics. Clinical characteristics: old age, history of commissurotomy, New York Heart Association class IV, permanent AF, severe pulmonary hypertension. Anatomical characteristics: echocardiographic score >8, Cormier score 3 (calcification of mitral valve of any extent as assessed by fluoroscopy), very small MVA, severe tricuspid regurgitation. For the definition of scores, see Supplementary Table 8.

ESC/EACTS 2021

Table 8 Contraindications for percutaneous mitral commissurotomy in rheumatic mitral stenosisa

Contraindications MVA >1.5 cm2a LA thrombus More than mild mitral regurgitation Severe or bi-commissural calcification Absence of commissural fusion Severe concomitant aortic valve disease, or severe combined tricuspid stenosis and regurgitation requiring surgery Concomitant CAD requiring bypass surgery CAD = coronary artery disease; LA = left atrium/left atrial; MVA = mitral valve area; PMC = percutaneous mitral commissurotomy. aPMC may be considered in patients with valve area >1.5 cm2 with symptoms that cannot be explained by another cause and if the anatomy is favourable.

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