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STEMI ECG

Standrad ECG Definition

  • ST-elevation at the J-point in 2 contiguous leads with the cut-point: ≥1 mm in all leads except V2-V3 (or >1mm from prior baseline)1
  • ST elevation V2 –V31
    • ≥2 mm in men ≥40 years
    • ≥2.5 mm in men <40 years
    • ≥1.5 mm in women regardless of age.
  • ST-segment elevation in aVR associated with ≥1 mm of ST depression in multiple leads may suggest left main coronary artery (LMCA) stenosis or occlusion.3

Posterior STEMI

  • ST depression in leads V1, V2, or V3 with an associated positive T wave in the standard 12-lead ECG
  • ST elevation of ≥0.5 mm in any posterior (V7, V8, V9) lead is recommended as the cut-off point. ST elevation of ≥1 mm has increased specificity and is recommended as the cut-off point in men aged <40 years.1

LBBB

Original Sgarbossa Criteria4

  • Concordant ST elevation ≥1 mm in leads with a positive QRS complex = 5 points
  • Concordant ST depression ≥1 mm in leads V1-V3 = 3 points
  • Excessive discordant ST elevation ≥5 mm in leads with a negative QRS complex = 2 points

A score >3 is specific for MI in patients with LBBB.

Smith criteria5

  • Replaced the 3rd item in Sgarbossa’s criteria to improve accuracy. “≥ 1 lead with ≥ 1 mm ST elevation and proportionally excessive discordant ST elevation, as defined by STE ≥ 25% of the depth of the preceding S-wave (an ST / S ratio of ≤ – 0.25)”
  • Removed the point system making all 3 criteria equal. Presence of any single criteria is deemed 80% sensitive and 99% specific in identifying acute MI in known LBBB.
Figure thumbnail gr1
Figure 1Abnormal, excessive discordance, with the ST segment and T wave in the opposite direction from QRS. Method of measurement: ST segment is measured at the J point, relative to the PR segment. R wave and S wave are also measured relative to the PR segment. Source

Left Main Disease

ST-segment elevation in aVR associated with ≥1 mm of ST depression in multiple leads may suggest left main coronary artery (LMCA) stenosis or occlusion.3

References

  1. Thygesen K, Alpert JS, Jaffe AS, et al. Fourth universal definition of myocardial infarction(2018). Circulation. 2018;138(20):e618-e651. PubMed
  2. Frank M, Sanders C, Berry BP. Evaluation and management of ST-segment elevation myocardial infarction in the emergency department. Emerg Med Pract. 2021;23(1):1-28. Article , PubMed
  3. O’Gara PT, Kushner FG, Ascheim DD, et al. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2013;127(4):e362-e425. Article
  4. Sgarbossa EB, Pinski SL, Barbagelata A, et al. Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. GUSTO-1 (Global utilization of streptokinase and tissue plasminogen activator for occluded coronary arteries) Investigators. N Engl J Med. 1996;334(8):481-487. PubMed
  5. Smith SW, Dodd KW, Henry TD, Dvorak DM, Pearce LA. Diagnosis of ST-elevation myocardial infarction in the presence of left bundle branch block with the ST-elevation to S-wave ratio in a modified Sgarbossa rule. Ann Emerg Med. 2012;60(6):766-776. PubMed

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