Approach
Mitral stenosis is a mechanical obstruction to inflow of the left ventricle. As such, definitive therapy for patients with rheumatic disease requires a mechanical solution by percutaneous balloon valvotomy, surgical mitral valve repair, or valve replacement. Definitive therapy should be offered to patients with severe symptomatic disease who are unlikely to benefit from medical therapy alone, and may be considered in some patients with severe asymptomatic disease.[22][23] Management of mitral annular calcification (MAC)-related mitral stenosis is similar to the management of rheumatic disease; however, balloon valvotomy is not recommended in these patients.
Rheumatic disease: progressive disease (gradient <5 mmHg, valve area >1.5 cm²)
Patients with less than severe disease do not benefit from mechanical therapy, because it is not likely to significantly increase an already relatively adequate valve area.
Rheumatic disease: severe asymptomatic disease (gradient >5 mmHg, valve area <1.5 cm²)
Asymptomatic patients with severe disease usually do not require therapy. However, balloon mitral valvotomy may be considered for patients with very severe disease (valve area <1.0 cm²) when valve morphology is favorable for that procedure or when atrial fibrillation intervenes. Pulmonary hypertension may also be considered in the decision to proceed to balloon valvotomy.[22][23]
Rheumatic disease: severe symptomatic disease (gradient >5 mmHg, valve area <1.5 cm²)
A diuretic may reduce left atrial pressure and relieve mild symptoms. However, patients with severe disease are unlikely to benefit from medical therapy alone, and mechanical relief from valve obstruction is often the only effective remedy for symptoms and for pulmonary hypertension.
Percutaneous balloon valvotomy is the treatment of choice when valve anatomy is suitable for this procedure.[22][23][33][34][35][36][37]
Valve mobility, calcification, leaflet thickening, and subvalvular apparatus distortion are graded on a severity score of 1 to 4.[29] Valves with a score of <9 are usually considered optimal for balloon valvotomy.
In patients with higher valve scores, surgery to perform open valve repair (commissurotomy) may be possible. However, mitral valve replacement is more commonly performed.
Patients with rheumatic mitral stenosis are usually relatively young. This complicates the choice of valve for replacement, as bioprosthetic valves are likely to suffer valve deterioration requiring repeat replacement within several years. Mechanical valves are durable and will likely last for the lifetime of the patient, yet are thrombogenic, and patients require anticoagulation with a vitamin K antagonist (e.g., warfarin).[22] Bleeding complications from the anticoagulants used to prevent thromboembolism occur approximately at a rate of 2% per year.[37] In view of the disadvantages of each option, patient preference has a key role in choosing which type of replacement valve to use.
For patients with multiple comorbid conditions that make open heart surgery high risk, balloon valvotomy may offer relief in rheumatic disease even when valve anatomy is suboptimal and valve score is high.
For patients with mitral stenosis in normal sinus rhythm who experience worsening of symptoms with exercise, heart rate control with a beta-blocker may be considered.[22] Ivabradine may be an alternative to beta-blockers for rate control in these patients. Three trials compared beta-blockers and ivabradine for exercise tolerance in patients with severe mitral stenosis.[38][39][40] In all three trials, ivabradine improved exercise tolerance compared with baseline and in two of the trials, ivabradine was superior to beta blockade.[38][39]
MAC-related disease
Medical therapy for MAC-related disease is identical to that of rheumatic disease (see above), with the exception of the type of anticoagulation used. While no studies exist to compare vitamin K antagonists to direct oral anticoagulants (DOACs) in MAC-related disease, current guidelines indicate that vitamin K antagonists are indicated in rheumatic disease because of ongoing inflammation. Thus DOACs may be suitable for atrial fibrillation in MAC patients.
Balloon valvotomy is not an appropriate treatment option for patients with MAC-related disease. Balloon valvotomy is ineffective in these patients because the restriction to flow resides not in the valve itself, but rather, in dense calcification of the annulus which is resistant to dilation. Unfortunately the other major option, surgical valve replacement, has a poor outcome due to the risk atrioventricular disruption when the calcium in the annulus is removed to permit placement of a valvular prosthesis.[41] In one study, the median 30-day surgical mortality was 6.3%, but was as high as 27%.[42] Further, most patients with MAC are older people and have multiple comorbidities, additionally worsening prognosis. In general, if such patients are considered for surgery, they should be referred to surgeons with a high volume experience in treating MAC-related disease.
Pregnancy
Pregnant women with mitral stenosis may develop symptoms in the second trimester, when the demand for cardiac output increases by around 70%.
A systematic review found a lack of evidence concerning effectiveness of the various treatments for valvular heart disease in pregnancy.[43] Diuretics are given to control mild symptoms. If symptoms worsen and heart failure threatens the life of mother and/or fetus, balloon valvotomy can be performed safely in patients with rheumatic disease.[44] MAC-related disease is extremely rare in pregnancy.
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