Mitral Valvuloplasty Treatment & Management

Symptoms in mild to moderate mitral stenosis can be improved with medical therapy. Beta blockers and calcium channel blockers help to control heart rate and increase diastolic filling time. Diuretics can help with heart failure symptoms. Severe symptomatic mitral stenosis should be treated with percutaneous mitral balloon valvuloplasty (PMBV) or surgically.

Surgical commissurotomy has been compared with percutaneous valvuloplasty in several randomized trials. ^{[9, 10, 11, 12]} Outcomes are consistently better with percutaneous valvuloplasty in patients who are good candidates. Surgical commissurotomy should, however, be considered in patients with severe subvalvular or calcific mitral valve disease.

A study compared surgical mitral valve replacement (MVR) with percutaneous valvuloplasty in patients with combined mitral stenosis and severe tricuspid regurgitation. ^[13] In this clinical setting, MVR with tricuspid repair was associated with improved clinical outcomes compared with PMBV. Surgical mitral valve replacement should also be considered in patients with valve morphology not amenable to percutaneous mitral balloon valvuloplasty (PMBV). In patients with persistent left atrial thrombus despite anticoagulation, surgical mitral valve replacement with left atrial appendage ligation should be considered.

In patients with isolated rheumatic mitral stenosis, there appears to be an association between balloon mitral valvuloplasty and a significant reduction of left atrial (LA) volume accompanied by significant improvement in LA volumetric functions. ^[14]

A study that evaluated maternal and fetal outcomes in 117 pregnant women in their second trimester who underwent PMBV for rheumatic mitral stenosis found the procedure was safe and effective as well as offered favorable maternal and short-term neonatal outcomes. ^[15] PMBV provided symptomatic relief and hemodynamic improvement, and a 100% success rate.

Percutaneous mitral balloon valvuloplasty (PMBV) should be performed in a qualified cardiac catheterization laboratory with experience in this procedure. transesophageal echocardiography (TEE)-guided PMBV usually requires intubation prior to the procedure and comanagement with an anesthesia team.

Dilatation is most often performed via an antegrade approach with transseptal puncture. A balloon catheter inserted from the femoral vein is advanced to the right atrium and across the atrial septum to access the mitral valve. The procedure can also be performed by a retrograde approach from the aorta across the aortic valve to access the mitral valve. This approach, however, requires arterial access with a large catheter.

Catheter placement and balloon inflation are guided by one or more of several available imaging modalities. Fluoroscopy is routinely performed and allows visualization of catheters during transseptal puncture and balloon inflation. Echocardiography is usually performed to assess mitral valve gradients pre- and postprocedurally. Transthoracic echocardiography (TTE), though less invasive, is sometimes limited as an intraprocedural imaging technique. TEE, the most commonly used echocardiographic modality in PMBV, can more reliably provide intraprocedural imaging and can confirm the location of the transseptal needle prior to septal puncture but usually requires patient intubation and anesthesia. Intracardiac echocardiography (ICE) decreases the risks of transseptal puncture by visualizing the fossa ovalis and tenting as the transseptal needle crosses, but ICE requires an additional venous puncture and is costly. ICE is also limited in accuracy for assessing mitral valve gradients and regurgitant flow.

The most commonly used device for percutaneous mitral balloon valvuloplasty (PMBV) is the Inoue balloon catheter. The single balloon inflates in three stages. After crossing the mitral valve, the distal portion of the balloon is first inflated. The catheter is then pulled back until the distal balloon opposes the valve. The proximal portion of the balloon is then inflated, securing the position of the balloon across the mitral valve. The middle portion of the balloon is then inflated with enough pressure to partially split the fused mitral valve leaflets. Repeated inflations are then performed at successively larger balloon diameters until a minimum gradient reduction is achieved or an increase in mitral regurgitation occurs. In cases of symmetric leaflet fusion, 40-60% of procedures result in a split of both commissures, whereas the remainder split only a single commissure. See video below.

Double balloon valvuloplasty can also be performed. This procedure requires 2 wires or a monorail balloon to be placed across the mitral valve into the left ventricle, potentially increasing the risk of left ventricular perforation. As compared with Inoue balloon, double balloon technique may increase subchordal damage. This is because the wires, instead of the balloon, are used to cross the valve and may trap between the chordal structure. A metal commissuratome has also been recently developed, though it is not available in the United States. ^[16] This reusable device is appealing in developing nations where cost prohibits the use of other balloon techniques. The stiff metal device requires a large catheter, increasing the risk of cardiac and vascular trauma.

The enlarged mitral orifice resultant from percutaneous mitral balloon valvuloplasty (PMBV) results in an immediate decline in left atrial pressure, a decrease in the transmitral pressure gradient, and a rise in cardiac output (see images below). Left atrial stiffness decreases, resulting in improved left atrial contraction and pump function (in sinus rhythm) or increased left atrial reservoir function (in atrial fibrillation). Older patients, who tend to have increased left ventricular diastolic pressures, and patients with diastolic dysfunction may have persistently elevated left atrial pressures. These patients’ symptoms may not be completely relieved with PMBV.

Mitral Valvuloplasty. These images are simultaneous tracings of pulmonary capillary wedge pressure and left ventricular pressure in a patient with mitral stenosis before valvuloplasty. The shaded area represents the gradient between the left atrium and the left ventricle. The mean gradient is 22 mmHg and the mitral valve area is 0.9 cm².

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Mitral Valvuloplasty. Pulmonary capillary wedge pressure and left ventricular pressure in the same patient as in the previous image immediately after valvuloplasty. The mean gradient had decreased to 7 mmHg and the mitral valve area increased to 1.25 cm².

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PMBV results in an immediate 10-25% improvement in pulmonary hypertension. ^[17] Pulmonary pressures continue to decline over the ensuing weeks or months, although severe pulmonary hypertension usually does not resolve. Atrial fibrillation resolves spontaneously in few patients after PMBV. One study found that direct-current cardioversion to sinus rhythm was successful in approximately 50% of patients 1 month after valvuloplasty with amiodarone administration, although atrial fibrillation recurred in half of these patients. ^[18] A left atrial diameter of less than 60 mm predicts a higher likelihood of maintaining sinus rhythm.

Baseline atrial fibrillation in patients with significant mitral stenosis appears to be significantly associated with worse symptoms and higher event rates following successful percutaneous mitral valvuloplasty relative to patients with baseline sinus rhythm. ^[19]  Consideration may be given to the clinical benefits of this procedure for patients with mitral valve area less than 1.5 cm² before the onset of atrial fibrillation.

The severity of mitral stenosis and/or mitral regurgitation should be assessed by echocardiography after percutaneous mitral balloon valvuloplasty (PMBV) and patients should maintain regular follow-up with a cardiologist. Participation in sports and exercise should be based on the degree of residual mitral stenosis, mitral regurgitation, and/or left ventricular dysfunction. The patient’s capacity to exercise should be formally evaluated at least to the level of anticipated activity.

Up to 20% of patients will develop recurrent symptomatic mitral stenosis. Repeat PMBV can be considered in these patients. Predictors for event-free survival after repeat valvuloplasty are the same as those for primary therapy.

Percutaneous mitral balloon valvuloplasty (PMBV) carries a significant risk of worsening mitral regurgitation, which usually arises at the site of commissurotomy and less frequently from leaflet laceration or subchordal damage. Approximately 30% of patients undergoing PMBV have some detectable increase in mitral regurgitation. ^[20] Approximately 12% of patients will have regurgitation that is greater than mild in severity. Severe regurgitation requiring mitral valve surgery during the initial hospitalization for PMBV occurs in only 2.5% of patients. The degree of resultant mitral regurgitation correlates with event-free survival rate.

The risk of death with PMBV is less than 1%. This risk is higher in elderly or severely ill patients and those in shock at the time of the procedure.

The risk of transient ischemic attack and or cerebrovascular accident is minimized with routine preprocedural transesophageal echocardiography (TEE) to exclude left atrial thrombus. With TEE, this risk is equivalent to other catheter-based procedures.

The risk of cardiac perforation is approximately 1%.

An iatrogenic atrial septal defect is almost always present immediately after PMBV by antegrade approach. This small puncture, however, almost always closes spontaneously within weeks. Less than 2% of patients have a persistent shunt fraction greater than 1.5:1, which is more likely if left atrial pressures are persistently elevated. ^[21]

Mitral valve area increases on average from 1.0 cm² to 2.0 cm² after percutaneous mitral balloon valvuloplasty (PMBV). Overall survival rates at 5 years are approximately 70% in the United States. ^[22] A preprocedural echocardiographic score of less than 8 predicts a 5-year event-free survival rate of 80%. ^[23] Mitral stenosis does occasionally progress. A mitral valve area (MVA) reduction greater than 0.3 cm² occurs in 27% of patients. Mitral regurgitation usually does not progress. ^[24]

The National Heart, Lung, and Blood Institute (NHLBI) Balloon Valvuloplasty Registry followed up with 736 patients after PMBV. ^[25] Event-free survival (free from death, mitral valve surgery, or repeat valvuloplasty) was 80% at 1 year, 71% at 2 years, 66% at 3 years, and 60% at 4 years.

A study followed patients for up to 20 years following PBMV (mean follow-up: 11.6 ± 4.9 years) in 441 patients. ^[26] The rate of cardiovascular death, need for mitral valve surgery or repeat PMBV were 9.1%, 27%, and 5.9% respectively. Survival free of major adverse cardiac events at 20 years was 35.9 ± 4.7%. ^[26]  

A novel echocardiographic scoring system based on calcification, especially commissural, and subvalvular involvement predicted outcomes after percutaneous mitral balloon valvuloplasty (PMBV) better than the standard score and may offer a complementary evaluation to the current scoring system. ^[27]

Controversy remains over the best treatment and role for mitral valvuloplasty in patients with asymptomatic moderate to severe mitral stenosis, symptomatic mild mitral stenosis, and symptomatic severe mitral stenosis with unfavorable anatomic characteristics.