Acute Myocardial Infarction, Myocardial infection. Patient

An acute myocardial infarction is caused by necrosis of myocardial tissue due to ischaemia, usually due to blockage of a coronary artery by a thrombus. Most myocardial infarctions are anterior or inferior but may affect the posterior wall of the left ventricle to cause a posterior myocardial infarction. Nearly half of potentially salvageable myocardium is lost within one hour of the coronary artery being occluded, and two thirds are lost within three hours.[1]

Myocardial infarction is now considered part of a spectrum referred to as acute coronary syndrome (ACS). This refers to a spectrum of acute myocardial ischaemia that also includes unstable angina and non-ST-segment elevation myocardial infarction (NSTEMI).[2]

The new criteria for diagnosing myocardial infarction are detection of rise and/or fall of cardiac biomarkers (preferably troponin) with at least one value above the 99th percentile of the upper reference limit, together with evidence of myocardial ischaemia with at least one of the following:[3, 4]

Cardiovascular examination findings can vary enormously:

see also the separate Chest Pain and Cardiac-type Chest Pain Presenting in Primary Carearticles.

Consider non-atherosclerotic causes of myocardial infarction in younger patients or if there is no evidence of atherosclerosis: coronary emboli from sources such as an infected cardiac valve, coronary occlusion secondary to vasculitis, coronary artery spasm, cocaine use, congenital coronary anomalies, coronary trauma, increased oxygen requirement (eg, hyperthyroidism) or decreased oxygen delivery (eg, severe anaemia).

See separate Acute Myocardial Infarction Management, Cardiovascular Risk Assessment and Cardiac Rehabilitation articles.

See separate Complications of Acute Myocardial Infarction article.

See separate Prevention of Cardiovascular Disease article.

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Acute Myocardial Infarction, Myocardial infection. Patient