Erythema multiforme (EM) is a skin reaction that comes from an infection or another trigger. EM is a type of allergic reaction. In most cases, it occurs in response to an infection. In rare cases, it is caused by certain medicines or body-wide (systemic) illness. Infections that may lead to EM include:
1 Heart attack. A heart attack can damage the area of the heart muscle that supports the mitral valve, affecting the function of the valve. If the damage is extensive enough, a heart attack can cause sudden and severe mitral valve regurgitation.  Abnormality of the heart muscle (cardiomyopathy).
Acute mitral valve regurgitation occurs when the mitral valve or one of its supporting structures ruptures suddenly, creating an immediate overload of blood volume and pressure in the left side of the heart. Your heart doesn't have time to adjust to the increased volume and pressure of blood (as it does in chronic MR).