Reviewing the evolution of treatment of mitral stenosis over the 80 years since the first successful treatment, Dr. Turi noted that strategies have come full circle. From initial closed commissurotomy to open repair, and again to closed repair with the advent of percutaneous balloon procedures in the 1980s.

Dr. Turi pointed out that the initial enthusiasm over the 50% reduction in gradient and doubling of valve area with balloon valvuloplasty was high. Also, many studies have shown that that superior hemodynamic results with the balloon approach are maintained to 3 and even 10 years, although with gradual loss of initial hemodynamic gain.

Current guidelines, however, indicate balloon commissurotomy only for severe mitral stenosis with Class III-IV symptoms. Dr. Turi reviewed factors suggesting lowering the threshold for such treatment.

The percutaneous balloon approach is relatively safe and non-disfiguring and is potentially an outpatient procedure. It is effective first-line therapy for mitral stenosis among patients with good anatomic features. Also, patients with mild disease may have disproportionately severe symptoms that merit effective treatment. On the other hand, early dilation of mild mitral stenosis (Class II) has a 2.9% mortality rate, causes mitral regurgitation in 6.7%, and stroke in 1.1%. Delaying and relying on medical therapy avoids such risks, but opens the door to others. They including progressive pulmonary hypertension, systemic embolization, pulmonary edema, hemoptysis, right ventricular failure and cardiac cirrhosis.

While urging a lower threshold for percutaneous therapy, Dr. Turi said that randomized trials are needed to show whether the excellent initial hemodynamic results with the balloon strategy actually slow progression to pulmonary hypertension, slow progression to atrial fibrillation, lower rates of cerebrovascular events, and have long-term positive effects on left ventricular function.