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How can a myocardial infarction damage the mitral valve or ventricular septum?

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The role of coronary artery disease in heart attack — cardiovascular disease This micrograph shows a cross section of a coronary artery narrowed by an atherosclerotic plaque (purplish matter inside the artery). Most heart attacks are caused by the rupture of an atherosclerotic plaque, which triggers the formation of a clot that abruptly blocks blood flow to part of the heart muscle.

A myocardial infarction (heart attack) involves the death of heart muscle tissue due to a lack of blood supply. This damage can lead to serious structural complications within the heart:

Mitral Valve Dysfunction: The infarction can interfere with the normal functioning of the mitral valve, which regulates blood flow between the left atrium and left ventricle. This damage can result in mitral insufficiency, where the valve fails to close adequately, allowing blood to leak backward into the atrium.12
Ventricular Septal Defect: The necrotic process can cause a rupture of the interventricular septum, the partition separating the left and right ventricles. This creates a ventricular septal defect, a condition that allows blood to flow abnormally between the two chambers, similar to certain forms of congenital heart disease.2

These structural failures occur because the infarction weakens the heart's architecture, potentially compromising the muscles and tissues necessary for proper valve operation and chamber integrity.12