ST-Segment Elevation Myocardial Infarction

ST-Segment Elevation Myocardial Infarction is a topic covered in the Washington Manual of Medical Therapeutics.

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General Principles

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.

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General Principles

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.

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