The large atrium may cause an abnormal heart rhythm called atrial fibrillation. The heartbeat becomes very irregular and often quite fast. Medicines are usually needed to control the heart rate and rhythm. If the medicines don't normalize the heart rhythm, you may need to be sedated and the rhythm converted with a brief electric shock. The scarring that damages the mitral valve may cause another problem.
Damaged valves are more likely to become infected by bacteria.
If an organism infects the valve, it further damages and may destroy it. Antibiotics, when properly given, prevent this. Although these infections are not very common, people with mitral stenosis should receive antibiotics before dental or genitourinary procedures. You may have mitral stenosis with few or no symptoms for a long time. When symptoms appear, your health care provider will suggest the proper treatment.