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Electrocardiographic diagnosis of myocardial infarction during left bundle branch block

S Serge Barold1, Bengt Herweg

  • 1Division of Cardiology, University of South Florida College of Medicine and Tampa General Hospital, Tampa, FL 33606, USA. ssbarold@aol.com

Cardiology Clinics
|August 31, 2006
PubMed

Insights

Diagnosing myocardial infarction (MI) with left bundle branch block (LBBB) on ECG is challenging. ST-segment deviation can help rule in acute MI, but older QRS criteria for old MI remain insensitive.

Area of Science:

  • Cardiology
  • Electrocardiography
  • Medical Diagnostics

Background:

  • Electrocardiographic diagnosis of myocardial infarction (MI) is complicated by left bundle branch block (LBBB).
  • Traditional ECG markers for MI in LBBB have limited utility.
  • Reperfusion therapy necessitates improved diagnostic accuracy for acute MI in LBBB.

Purpose of the Study:

  • To review the current utility of ECG criteria for diagnosing acute and old MI in patients with LBBB.
  • To highlight the importance of ST-segment deviation for ruling in acute MI.
  • To assess the re-evaluation status of QRS-based criteria for old MI.

Main Methods:

  • Literature review of established and proposed ECG criteria for MI in LBBB.
  • Analysis of the diagnostic performance of ST-segment deviation and QRS changes.

Main Results:

  • ST-segment deviation is the primary ECG sign for ruling in acute MI in LBBB.
  • QRS-based criteria for old MI exhibit low sensitivity but high specificity.
  • Older criteria require re-evaluation due to limited sensitivity.

Conclusions:

  • Accurate ECG diagnosis of MI in LBBB remains difficult.
  • ST-segment criteria are valuable for ruling in acute MI.
  • Further research is needed to improve ECG diagnosis of old MI in LBBB.

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