Early Percutaneous Intervention May Help Asymptomatic Mitral Stenosis

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Although balloon valvuloplasty is an accepted treatment for symptomatic moderate mitral stenosis, patients with asymptomatic disease are often managed with ‘watchful waiting’ alone. A new study published online January 13, 2012, ahead of print in the European Heart Journal suggests that the benefits of early intervention may outweigh the risks even in this subgroup.

According to the paper, European and American guidelines discourage intervention for mild mitral stenosis but recommend percutaneous treatment for selected asymptomatic patients with significant pulmonary hypertension, high thromboembolic risk, or severe mitral stenosis.

For the nonrandomized study, Duk-Hyun Kang, MD, of Asan Medical Center (Seoul, South Korea), and colleagues prospectively enrolled 244 consecutive patients with moderate rheumatic mitral stenosis who were potential candidates for early percutaneous intervention. The choice between percutaneous mitral commissurotomy (n = 106) and standard treatment (n = 138), which involved observation and no medical therapy, was at physician discretion. Conventionally treated patients who developed symptoms during the study were referred for percutaneous treatment or mitral valve surgery.

Treatment Successful, Effective

Over a median follow-up duration of 8.3 years, the percutaneously treated group had 3 cardiovascular deaths (2.8%) and 5 cerebral infarctions (4.7%). Conventional treatment resulted in 16 cardiovascular deaths (11.6%), 12 cerebral infarctions (8.7%), and 7 systemic embolic events (5.1%). Three-quarters of valvuloplasty patients remained event-free and asymptomatic by the end of the study, but only 44% of conventionally treated patients did so.

As a whole, patients who underwent early valvuloplasty had better estimated 11-year rates of the primary endpoint—freedom from cardiovascular mortality, cerebral infarction, systemic embolic events, and valvuloplasty-related complications—compared with those who had standard care (89 ± 4% vs. 69 ± 5%; P < 0.001). But results were similar for both strategies among patients without atrial fibrillation or previous embolism at baseline (86 ± 5% with valvuloplasty and 79 ± 6% with conventional treatment; P = 0.28).

Propensity score matching identified 62 pairs of patients. In this analysis, percutaneous treatment was associated with a reduced risk of cardiovascular events compared with standard care (HR 0.327; 95% CI 0.112-0.954; P = 0.041).

Promising in Experienced Hands, Selected Patients

In an e-mail communication with TCTMD, Dr. Kang explained that asymptomatic patients with mitral stenosis have good survival but tend to deteriorate suddenly after atrial fibrillation or embolism. Because the percutaneous treatment has high procedural success and can potentially reduce the risk of embolism, the hope is that it might improve clinical outcomes.

However, “[o]wing to inherent risks of procedure-related complications such as cardiac tamponade and development of severe mitral regurgitation, early preemptive [percutaneous mitral commissurotomy] should be performed by experienced interventionalists,” he cautioned.

Other factors to consider are that percutaneous treatment “should not be performed in patients with mild mitral stenosis or poor mitral valve morphology,” Dr. Kang advised, noting that echocardiographic evaluation of morphology and cardiac rhythm can aid in patient selection. After treatment, he said, effective anticoagulation therapy should be maintained in all patients with paroxysmal or persistent atrial fibrillation during follow-up.

Relevance Depends on Geographic Region

Robert O. Bonow, MD, of Northwestern University Feinberg School of Medicine (Chicago, IL), explained that mitral stenosis almost always arises from rheumatic fever. Because the disease has been largely eradicated in the United States and Western Europe, cardiologists in those regions rarely encounter the condition. In his own experience at an academic medical center, Dr. Bonow said he typically treats 5 to 10 cases per year, “whereas, if you’re in India, you’ll do 10 or 20 a day.”

Balloon valvuloplasty for mitral stenosis has been available for 30 years, he reported, and while it now produces results “equivalent to what can be achieved with surgery,” the question is whether it can alter disease progression in asymptomatic patients. “It’s often not curative. It usually prolongs the natural history. Many patients will redevelop stenosis over time and ultimately may need either another balloon procedure or surgery. But in some patients you can get really long lasting results that are quite good,” he commented.

But Dr. Bonow stressed that a prospective randomized trial is still necessary before changing treatment guidelines.

Other caveats include the fact that the current study enrolled patients whose echo risk scores indicated a high likelihood of success, he noted. And at approximately 50 years of age, subjects were older than is often seen in developing countries, Dr. Bonow added, where rheumatic fever “is a very virulent disease that strikes young people and causes huge economic problems [by taking people out of the workforce].”

Study Details

Balloon valvuloplasty was completed successfully in 100% of attempted cases, with no need for urgent surgery. No procedure-related deaths occurred. The incidence of severe mitral regurgitation was 2%. Mitral valve area increased from 1.26 ± 0.11 cm² to 2.07 ± 0.28 cm² immediately after treatment (P < 0.001).

Women made up 78% of the cohort, and median patient age was 51 ± 11 years. Most characteristics were similar between the 2 treatment groups. However, conventionally treated patients were older, more likely to have hypertension, and had a higher total echo score, larger mitral valve area, and lower pulmonary artery systolic pressure than those who underwent early intervention.

 

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Source:
Kang D-H, Lee CH, Kim D-H, et al. Early percutaneous mitral commissurotomy vs. conventional management in asymptomatic moderate mitral stenosis. Eur Heart J. 2012;Epub ahead of print.

 

 

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