Mitral valve thickening is a feature of mitral valve stenosis and can cause complications that include atrial fibrillation, infective endocarditis, pulmonary hypertension, pulmonary edema and systemic embolisms, explains Medscape. People with mitral valve thickening usually do not have symptoms until the third and fourth decades of life.
The mitral valve provides outflow of blood into the left ventricle in the heart, according to Medscape. When stenosis occurs, the flow of blood from the left atrium to the left ventricle is obstructed because the valve does not open well. The most common cause of mitral valve stenosis is acute rheumatic carditis from rheumatic fever.