The valve is positioned between the upper and lower heart chambers on the left side of the heart. Mitral valve prolapse is common in adults with otherwise normal hearts. Prolapse usually affects only the mitral valve. The valve leaflets may be stretched lengthwise and become thickened. The tissue strands that anchor the valve to the heart muscle may stretch.
Prolapse occurs in people with rare inherited diseases of connective tissue.
They have abnormal elasticity of their skin and other body tissues, as well as abnormalities in their bones. This group includes people with Marfan's syndrome or with Ehlers-Danlos syndrome. Prolapse of an otherwise normal mitral valve sometimes occurs when the small heart muscles that control and support the valve are damaged by a heart attack. Most people have no symptoms. You may notice the symptoms more when you are active or exercising.