Mitral stenosis refers to a decreased mitral valve orifice area resulting in obstruction of blood flow from the left atrium into the left ventricle during diastole. The orifice area of a normal mitral valve is 4–6 cm². Patients become symptomatic during increased physical activity when the mitral valve area decreases to less than 2.5 cm². Symptoms may occur at rest when the mitral valve orifice area is less than 1.5 cm² [1–3].

Rheumatic heart disease is the leading cause of mitral stenosis worldwide. This disease process leads to thickening of the mitral valve leaflets, thickening and fusion of subvalvular chordae as well as fusion of commissures. Less commonly, mitral stenosis is associated with carcinoid syndrome, mitral annular calcification, left atrial neoplasm, systemic lupus erythematosus, cor triatriatum and congenital abnormalities, such as parachute mitral valve [4–7].

Patients most often report symptoms of dyspnea on exertion that may progress to shortness of breath at rest. This symptom stems from progressively increased left atrial pressure from obstructed blood flow through small mitral valve. This leads to elevated pulmonary venous and pulmonary arterial pressure. Pulmonary hypertension may result in hemoptysis.

Patients may also experience palpitations. Elevated left atrial pressure leads to left atrial enlargement, which may result in new-onset atrial fibrillation. This places patients at a higher risk for thrombus formation and stroke.

Long-standing pulmonary hypertension contributes to right ventricular failure, which may result in significant peripheral edema [8].

The most recent recommendations from the American Heart Association include anticoagulation therapy for patients with mitral stenosis and a history of any of the following:

Additionally, heart rate should be controlled in patients with mitral stenosis who develop atrial fibrillation (i.e., treatment with beta-blockers) [9, 10].

In patients with mitral stenosis stemming from rheumatic heart disease, valve leaflets appear thickened with varying degree of valvular and subvalvular calcification. Depending on the duration and severity of the mitral stenosis, echocardiography reveals an increased transmitral pressure gradient and left atrial enlargement. Long-standing pulmonary hypertension associated with mitral stenosis results in dilatation of the right ventricle and subsequent right ventricular failure. Up to 30% of patients with mitral stenosis may have left ventricular dysfunction [11, 12].

Echocardiography is the recommended tool to grade mitral stenosis, which can be evaluated using: pressure gradient, mitral valve area planimetry, pressure half-time, and the continuity equation. The grading of mitral stenosis is based mainly on the direct measurement or calculation of the mitral valve area (mean pressure gradient and pulmonary artery pressure values are only supportive findings). MVA of more than 1.5 cm² corresponds to mild mitral stenosis, MVA between 1.0 and 1.5 cm² corresponds to moderate mitral stenosis, and MVA of less than 1.0 cm² is classified as severe mitral stenosis [11, 12].

Auscultation reveals a diastolic murmur that is appreciated best at the apex with the patient resting on left side. Often, there is an opening snap heard after S2 [13].

The definition of pulmonary hypertension includes a mean pulmonary artery pressure above 25 mmHg and a pulmonary artery occlusion pressure below 15 mmHg on repeated measurements [14].