ST-Segment Elevation Myocardial Infarction | Washington Manual of Medical Therapeutics (2024)

Definition

• STEMI is defined as a clinical syndrome of myocardial ischemia in association with persistent ECG ST elevations (see “Diagnostic Testing” section).
• STEMI is a medical emergency.
• Compared to UA/NSTEMI, STEMI is associated with a higher in-hospital and 30-day morbidity and mortality. Left untreated, the mortality rate of STEMI can exceed 30%, and the presence of mechanical complications (papillary muscle rupture, ventricular septal defect [VSD], and free wall rupture) increases the mortality rate to 90%.
• Ventricular fibrillation (VF) accounts for approximately 50% of mortality and often occurs within the first hour from symptom onset.
• Keys to treatment of STEMI include rapid recognition and diagnosis, coordinated mobilization of health care resources, and prompt reperfusion therapy.
• Mortality is directly related to total ischemia time.
• AHA/ACC guidelines provide a more thorough overview of STEMI.¹

Epidemiology

• STEMI accounts for approximately 25%–30% of ACS cases annually, and the incidence has been declining.
• Over the last several decades, there has been a dramatic improvement in short-term mortality to the current rate of 6%–10%.
• Approximately 30% of STEMI presentations occur in women, but outcomes and complications continue to be worse compared with male counterparts.

Pathophysiology

• STEMI is caused by acute, total occlusion of an epicardial coronary artery, most often due to atherosclerotic plaque rupture/erosion and subsequent thrombus formation.
• As compared to NSTEMI/UA, thrombotic occlusion is complete such that there is total transmural ischemia/infarct in the distribution of the large, occluded artery.