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).
Insufficiency of the atrioventricular valves causes systolic murmurs: mitral regurgitation(MR) and tricuspid regurgitation(TR). There are four important areas used for listening to heart sounds. These are: Aortic area, Pulmonic area, Tricuspid area, Mitral Area (Apex).