What Causes Mitral Regurgitation?

There are two types of mitral regurgitation (MR):

• Primary MR (degenerative) is caused by a problem with the mitral valve itself.
• Secondary MR (functional) is caused by a problem with the left bottom chamber, or ventricle, of the heart.

Common causes of mitral regurgitation include:

Mitral valve prolapse: The valve's tissue flaps or the tendon cords that anchor the valves are weakened and stretch. The flaps then bulge into the top chamber, or atrium, with each heartbeat.

Rheumatic fever: This can be a complication of untreated strep throat. It can damage the valve in childhood and lead to MR in adults. This most commonly occurs in underdeveloped countries.

Heart attack: A heart attack can cause decreased blood flow to the area of the heart that supports the mitral valve, making it weak. The change can be quite severe and sudden if the tendon cords are ruptured because of the heart attack.

Weakened heart (or cardiomyopathy): Sometimes, the bottom chamber (ventricle) of the heart stretches. When this happens, the mitral valve also is stretched and becomes leaky.

Endocarditis: This bacterial infection can attach to the heart valves and damage the valve itself.

Trauma: For example, trauma to the chest in a car accident.

Congenital heart defects: Some people are born with either leaky heart valves or enlarged hearts that make it hard for the valves to close.

Drugs: The medications ergotamine and bromocriptine have been linked with mitral regurgitation. Weight loss medication, such as fenfluramine (fen-phen), has also been associated with this valve problem. This medication has been taken off the market. If you have taken these medications in the past, talk to your provider about getting your heart valves checked. Radiation exposure during cancer treatment also could contribute to the valve changing shape.

Age: Over time, your body can deposit calcium around the valves and make it hard for your valves to close tightly.