ECG Guide: Part II

STEMI

STEMI

  • ST-segment elevation ≥ 1mm in two contiguous leads
  • : ≥ 2mm V2-V3
  • : ≥ 1.5mm V2-V3

Posterior STEMI

  • ST-segment depression V1-V3 Posterior ECG
  • ST-segment elevation ≥ 0.5mm in V7-V9

Sgarbossa Criteria

  • Evaluation for STEMI in LBBB or paced rhythm
  • Normal: ST-segment discordant with QRS

    • QRS associated with ST-segment depression
    • QRS associated with (commensurate) ST-segment elevation
  • Score ≥ 3 98% specific for MI

Elevation

  • Concordant ST-segment elevation ≥ 1mm in any lead (5 points)

Depression

  • Concordant ST-segment depression ≥ 1mm in V1-V3 (3 points)

Discordant Elevation

  • Discordant ST-segment elevation ≥ 5mm in any lead (2 points)

Modified Sgarbossa Criteria

  • ST:S ratio ≥ 0.25 in any lead
  • Presence of any criterion is positive

Other Causes of ST-segment Elevation

Benign Early Repolarization

  • Concave ST-segment elevation
  • Notch at J-point
  • Asymmetric T-waves (steeper descent)

Pericarditis

  • Diffuse ST-segment elevation (except aVR)
  • PR-segment depression
  • Ratio: ST-elevation to T-wave amplitude ≥ 0.25 in V6 suggests pericarditis

LVH Strain

  • ST-segment elevation in V1-V3 in the setting of LVH

LV Aneurysm

  • Q-waves with ST-segment elevation in precordial leads

Ischemia and Prior Infarcts

Wellens: Type A

Wellens: Type B

Q-waves

  • ≥ 40ms duration
  • Depth ≥ 25% of R-wave height

Syncope

ARVD

  • Epsilon wave

Brugada Syndrome: Type 1

  • Type 1: Coved ST-segment elevation

Brugada Syndrome: Type 2

  • Type 2: Saddle-back ST-segment elevation

HCM

  • Deep, narrow Q-waves

Wolff-Parkinson-White

  • Shortened PR-interval
  • Delta-wave

Other

Atrial Abnormalities

  1. Normal
  2. RAA: P-wave amplitude > 2.5mm in inferior leads
  3. LAA: P-wave duration increased (terminal negative portion >0.04s), amplitude of terminal negative component >1mm below isoelectric line in V1

Left Bundle Branch Block


  • QRS duration > 0.12s (3 boxes)
  • Broad or notched R-wave with prolonged upstroke in I, aVL, V5, V6
  • Associated ST-segment depression and T-wave inversion
  • Reciprocal changes in V1, V2 (deep S-wave)
  • Possible LAD

Right Bundle Branch Block


  • QRS duration > 0.12s (3 boxes)
  • RSR’ in V1, V2
  • Reciprocal changes in I, aVL, V5, V6 (deep S-wave)

Axes

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