ST segment elevation

Background

• Its presence must be explained (there is no "nonspecific ST elevation")
• Not a specific marker for STEMI

DDX

1. Myocardial Ischemia
   1. STEMI
   2. Wellens' Syndrome
   3. Ventricular aneurysm
   4. Coronary spasm
2. Pericarditis
3. Early repolarization
4. LBBB
5. LVH
6. Misc
   1. Meds: TCA, digoxin
   2. RV pacing (appears as LBBB)
   3. Hyperkalemia
   4. Hypothermia
      1. "Osborn J waves"
   5. Brugada Syndrome

Early Repolarization versus STEMI

• Early Repolarization suggested by:
  • ST elevation <4mm
  • Notched J point
  • Concave or saddle-back ST morphology
  • No reciprocal changes

LVH versus STEMI

• Difficult to exclude MI in pt with LVH (pt already at risk for MI)
• Best aid is prior ECG or serial ECGs

LBBB versus STEMI

See Sgarbossa's Criteria

STEMI

• ST elevation in those leads that reflect the distribution of a single coronary artery
  • RCA: II, III, aVF (inferior)
  • LAD: V1-V4 (antero-septal)
  • Circumflex: V5-V6, I, aVL (lateral)
  • Dominant left circulation: infero-lateral
• ST morphology
  • Concave up versus convex
    • Convex has Sp 97%, Sn 77%
• Look for reciprocal ST depression
  • 35% of anterior STEMI have ST depression in inferior leads
  • 80% of inferior STEMI have ST depression in anterior leads
    • However, may represent reciprocal changes OR posterior STEMI

Source

• ST Elevation Lecture, Dr. Niemann, Harbor-UCLA