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How does a blockage in a coronary artery damage the heart muscle?

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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 blockage in a coronary artery—often caused by a thrombus forming over an atherosclerotic plaque—deprives a segment of the heart muscle of essential blood flow.12

This restriction of blood supply leads to myocardial infarction, a condition characterized by the death of heart muscle cells, known as necrosis. In some instances, even if the blockage is not absolute, the heart muscle's metabolic demands may exceed the oxygen and nutrients provided by the restricted blood flow, resulting in the death of these deprived cells.1

The resulting damage can have several severe consequences:
* Structural Complications: The infarction may cause a rupture of the ventricular wall or the interventricular septum, or interfere with the function of the mitral valve.1
* Functional Impairment: The loss of viable muscle tissue can lead to heart failure or arrhythmias, as the heart's ability to pump efficiently is compromised.12
* Healing: Over several weeks, the body replaces the necrotic tissue with scar tissue, which may leave residual evidence of cardiac malfunction.1