MI DEFINITIONS 

ACUTE MYOCARDIAL INFARCTION

Elevated troponin WITH clinical evidence of ischemia

TYPE 1 MI

MI WITH plaque rupture and thrombus

TYPE 2 MI

MI with imbalance between oxygen supply and demand.  NO ruptured plaque and thrombus.  May be due to:

  • Vasospasm
  • Coronary dissection
  • Coronary embolism
  • O2 supply-demand mismatch, with or without underlying CAD.  May be due to:
    • Anemia
    • Hypotension
    • Hypoxia
    • Bradycardia
    • Hypertension
    • Tachycardia 

CLINICAL EVIDENCE OF ISCHEMIA (MUST HAVE ONE)

  • Symptoms suggestive of ischemia 
  • ECG changes suggestive of ischemia – new ST segment elevation or depression, new BBB, new pathologic Q waves, new T wave inversions
  • Echo changes suggestive of ischemia – new wall motion abnormalities

INSTEAD OF DEMAND ISCHEMIA, CONSIDER TYPE 2 MI WHEN THERE IS ELEVATION IN TROPONIN WITH CLINICAL EVIDENCE OF ISCHEMIA.

If there is NO clinical evidence of ischemia, an elevation in troponin should be termed, “non-MI elevated troponin”.  THIS IS NOT A MYOCARDIAL INFARCTION!

Patients with acute MI (any type) are inpatient appropriate!