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Myocardial Infarction (MI)

Heart attack; death of myocardium from sudden coronary occlusion

Definition

A myocardial infarction (MI) is the death of cardiac muscle tissue due to sudden, complete or partial occlusion of a coronary artery. Most commonly from atherosclerotic plaque rupture and thrombus formation.

Classification

  • STEMI: ST-elevation MI; complete occlusion. Requires PCI within 90 minutes ('door-to-balloon').
  • NSTEMI: Non-ST-elevation MI; partial occlusion.
  • Unstable angina: Chest pain without infarction.

Classic Presentation

Crushing substernal chest pain radiating to left arm, jaw, back; dyspnea, diaphoresis, nausea, sense of impending doom, such as atypical in women, diabetics, elderly (fatigue, epigastric pain alone).

Immediate Management (MONA-B)

  1. Morphine for unrelieved chest pain
  2. Oxygen if SpO2 less than 90%
  3. Nitroglycerin sublingual (if SBP greater than 90)
  4. Aspirin 162 to 325 mg chewed
  5. Beta-blocker and antiplatelet (clopidogrel)
  6. 12-lead ECG within 10 minutes; troponin; PCI (STEMI) or angiography

NCLEX Relevance

MI is a 'first priority' topic, such as mONA, door-to-balloon less than 90 minutes.