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).
In adults, the most common cause of severe aortic regurgitation is rheumatic fever. Mild cases are often caused by a bicuspid aortic valve (where the valve has 2 leaflets instead of 3) and severe high blood pressure (a diastolic pressure more than 110 mm Hg).