Mitral valve stenosis is a heart condition in which the mitral valve fails to open as wide as it should. When this happens, not as much blood can flow from the left atrium to the left ventricle. Over time, mitral valve stenosis can cause the left atrium to work harder to pump blood through the narrowed valve.

Mitral valve stenosis can lead to heart failure and complications such as stroke, heart rhythm problems (such as atrial fibrillation), fluid buildup in the lungs, and blood clots.