**3. Patient selection**

#### **3.1. Indications**

The mitral valve is almost always affected in clinically manifested patients, followed by the aortic and tricuspid valves. Mitral stenosis (MS) is the cardinal valvular lesion in RHD and is particularly amenable to transcatheter therapy when it is isolated or dominant and the anatomy is favorable. When left untreated, severe MS deteriorates the functional status of the patients and worsens their long-term outcomes [3]. Rarely, other etiologies might cause MS (i.e., connective tissue disorders, drugs, and congenital abnormalities). Today, degenerative calcified MS, failure of the bioprosthetic mitral valve, and overcorrection of mitral regurgitation (MR) are increasingly seen. Unlike rheumatic MS, these non-rheumatic mitral valve obstructions are not associated with commissural fusion and are not generally relieved by percutaneous balloon mitral valvuloplasty (BMV). When applied in correctly selected subjects and performed by experienced operators, a successful BMV procedure can improve symptoms and long-term survival of the patients and is, therefore, the method of choice in

Echocardiography is essential in the diagnosis and quantification of the severity of MS. Transthoracic echocardiography (TTE) provides sufficient data in most patients and should be performed in patients at initial presentation, in those with changing symptoms, and in asymptomatic patients periodically (**Figure 1**). It shows the restriction of the mitral valve opening caused by commissural fusion and the so-called doming of the mitral valve, thickness and calcifi-

half-time (PHT) ≥ 150 ms correspond to severe MS. PHT is affected by left ventricular (LV) diastolic dysfunction and the severity of mitral and aortic regurgitation, while planimetry-derived MVA is more accurate and should be used for decision-making in most patients [6]. Mitral valve resistance might be a better predictor of hemodynamic burden of MS and can be used to determine the need for BMV in borderline cases [7]. The other parameters that are evaluated include transmitral valve gradient, MR severity, concomitant valvular involvement, atrial size, left and right ventricular functions, and pulmonary arterial pressure. Transesophageal echocardiography (TEE) is valuable when the images derived from TTE are not satisfactory or when the patient is candidate for BMV to rule out clots in the left atrium (LA) and the left atrial appendage (LAA) as

Cardiac catheterization, aside from guiding the procedure, is indicated when echocardiography is nondiagnostic. It is not routinely indicated; however, it is necessary when the results from echocardiography are ambiguous, when the severity of other valvular lesions is evaluated, and when there is a suspicion of coronary artery disease. Before BMV, measurement of the mitral valve gradient, pulmonary arterial pressure, and MVA using the Gorlin equation can

be helpful in borderline cases and for confirming the severity of MS.

and a pressure

cation of the leaflets, and chordal thickening. A mitral valve area (MVA) ≤ 1.5 cm<sup>2</sup>

the treatment of patients with severe rheumatic MS [4, 5].

well as for a detailed evaluation of MR severity.

**2.2. Hemodynamic study**

**2. Evaluation of severity**

**2.1. Echocardiography**

100 Interventional Cardiology

BMV causes the splitting of the fused commissures and increases the MVA. Patients with symptomatic severe rheumatic MS with an MVA ≤ 1.5 cm<sup>2</sup> should be thoroughly evaluated and subjected to BMV if the valvular morphology is suitable [8] (**Figure 2**). Dyspnea is the most common symptom but it is not prominent in some patients. Additional attributable symptoms are exercise intolerance, fatigue, and chest pain. Given the proved long-term efficacy of BMV, even minimal symptoms should be regarded as the indication for intervention considering that this procedure is relatively safe in experienced hands. Patients with less severe obstruction (MVA > 1.5 cm2 ) remain asymptomatic for many years and do not need non-pharmacologic intervention [9]. In addition, asymptomatic patients with very severe MS (MVA ≤ 1 cm<sup>2</sup> ) are reasonable candidates for BMV. In patients with asymptomatic severe MS (MVA ≤ 1.5 cm<sup>2</sup> ), BMV can be performed if pulmonary hypertension is present (pulmonary artery systolic pressure ≥ 50 mm Hg at rest and ≥ 60 mm Hg with exercise). Atrial fibrillation (AF) worsens the prognosis in patients with severe MS through deteriorating functional status, progressing structural damage, and increasing thromboembolic risk [10, 11]. Meanwhile, AF can be an indicator of progressive MS [12]. As a result, new AF in a

**Figure 2.** Management of patients with severe mitral stenosis.

patient with severe MS mandates special consideration and might be an indication for BMV [8, 13]. The other potential indication for BMV is the presence of symptoms in a patient with mild MS (MVA > 1.5 cm2 ) with the evidence of significant obstruction (pulmonary capillary wedge pressure >25 mm Hg) during exercise. BMV as a therapeutic option in a patient with the latter scenario should be only considered after a comprehensive hemodynamic study and the exclusion of other potential causes. In recent practice, we encounter a subset of very symptomatic old patients with severe MS and unfavorable valve anatomy who were not candidated for mitral valve replacement (MVR) because of their comorbidities. BMV might be considered in these patients, although the immediate result is suboptimal, complications are more frequent, and long-term efficacy is limited [8, 14].

#### *3.1.1. Anatomic eligibility*

When the patient is considered a likely candidate for BMV, morphologic characteristics should be evaluated using echocardiography. The Wilkins score comprises four echocardiographic characteristics of the mitral valve, including leaflet mobility, leaflet thickness, leaflet calcification, and subvalvular apparatus, each given a 1- to 4-point value according to the predefined definitions [15]. Patients with Wilkins scores ≤ 8 are particularly suitable for BMV. This means that the mitral valve is sufficiently pliable and most often does well in response to balloon dilatation. In our practice, most patients have Wilkins scores between 8 and 10. BMV in these relatively fibrotic, rigid, and calcified valves often results in unpredictable and somehow suboptimal acute and late final MVAs, but many patients still experience acceptable and durable functional recovery, deferring eventual surgery. The ideal patients do not have MR more than moderate in severity, and the LA and LAA are free from thrombi. Significant concomitant valvular involvement including more-than-moderate aortic stenosis and regurgitation and tricuspid stenosis should not be presented. Secondary tricuspid regurgitation, even if it is significant, is not a limiting factor and most patients experience reduction in its severity after successful BMV.

#### **3.2. Contraindications**

patient with severe MS mandates special consideration and might be an indication for BMV [8, 13]. The other potential indication for BMV is the presence of symptoms in a patient with

wedge pressure >25 mm Hg) during exercise. BMV as a therapeutic option in a patient with the latter scenario should be only considered after a comprehensive hemodynamic study and the exclusion of other potential causes. In recent practice, we encounter a subset of very symptomatic old patients with severe MS and unfavorable valve anatomy who were not candidated for mitral valve replacement (MVR) because of their comorbidities. BMV might be considered in these patients, although the immediate result is suboptimal, complications

When the patient is considered a likely candidate for BMV, morphologic characteristics should be evaluated using echocardiography. The Wilkins score comprises four echocardiographic characteristics of the mitral valve, including leaflet mobility, leaflet thickness, leaflet calcifica-

are more frequent, and long-term efficacy is limited [8, 14].

**Figure 2.** Management of patients with severe mitral stenosis.

) with the evidence of significant obstruction (pulmonary capillary

mild MS (MVA > 1.5 cm2

102 Interventional Cardiology

*3.1.1. Anatomic eligibility*

When the Wilkins score is >10, BMV is generally ineffective and is, instead, associated with a higher incidence of severe MR and should, therefore, be avoided. The severity of preprocedural MR predicts the possibility of severe MR after the procedure that is associated with a poor longterm outcome of BMV. Moderate-to-severe MR (≥3+) is regarded a contraindication for BMV considering that the procedure itself aggravates MR in many cases. LA thrombi or thrombi on the interatrial septum are the absolute contraindications of transseptal puncture and BMV, whereas LAA thrombi are considered a relative contraindication. Bicommissural and fluoroscopic valve calcification are associated with a poor outcome following BMV [16]. When the commissural fusion is absent, BMV is ineffective and should not be used. Many patients with MS receive oral anticoagulation because of AF. Transseptal puncture should be avoided in the presence of an International Normalized Ratio (INR) >1.5 or within 4 hours after the administration of intravenous heparin. The contraindications for BMV are outlined in **Table 1**.


**Table 1.** Contraindications to BMV.
