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).
Heart valves can have one of two malfunctions: regurgitation (or leakage of the valve). The valve(s) does not close completely, causing the blood to flow backward through the valve. This results in leakage of blood back back into the atria from the ventricles (in the case of the mitral and tricuspid valves) or leakage of blood back into the ventricles (in the case of the aortic and pulmonary valves).