MI Diagnosis in LBBB or paced rhythm: Difference between revisions

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In case of a [[Intraventricular Conduction|left bundelbranch block (LBBB)]], infarct diagnostics based on the ECG is difficult. The ST segments are always abnormal in a LBBB, so new ischemia can not be detected. A new LBBB is always pathologocal and can be a sign of myocardial  infarction. The criteria (Sgarbossa <cite>LBTB</cite>) that can be used in case of a LBBB and suspicion of infarction are:
*ST elevation > 1mm in leads with a positive QRS complex (concordance in ST deviation) (score 5)
*ST depression > 1 mm in V1-V3 (discordance in ST deviation) (score 3)
*ST elevation > 5 mm in leads with a negative QRS complex (discordance in ST deviation) (score 2)
At a score-sum of 3, these criteria have a specificity of 90% for detecting a myocardial infarction.
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==Examples==
==Examples==
<gallery>
<gallery>
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Image:MI in LBBB 02.jpg|The same patient as in the first example 2 months before the myocardial infarction. Normal LBBB pattern.
Image:MI in LBBB 02.jpg|The same patient as in the first example 2 months before the myocardial infarction. Normal LBBB pattern.
</gallery>
</gallery>
==References==
<biblio>
#LBTB pmid=11265742
</biblio>

Revision as of 08:29, 23 July 2007

In case of a left bundelbranch block (LBBB), infarct diagnostics based on the ECG is difficult. The ST segments are always abnormal in a LBBB, so new ischemia can not be detected. A new LBBB is always pathologocal and can be a sign of myocardial infarction. The criteria (Sgarbossa [1]) that can be used in case of a LBBB and suspicion of infarction are:

  • ST elevation > 1mm in leads with a positive QRS complex (concordance in ST deviation) (score 5)
  • ST depression > 1 mm in V1-V3 (discordance in ST deviation) (score 3)
  • ST elevation > 5 mm in leads with a negative QRS complex (discordance in ST deviation) (score 2)

At a score-sum of 3, these criteria have a specificity of 90% for detecting a myocardial infarction.

Examples

  • Acute myocardial infarction in in a patient with a pacemaker and LBBB. Concordant ST elevation in V5-V6 are clearly visible.

    Acute myocardial infarction in in a patient with a pacemaker and LBBB. Concordant ST elevation in V5-V6 are clearly visible.

  • The same patient as in the first example 2 months before the myocardial infarction. Normal LBBB pattern.

    The same patient as in the first example 2 months before the myocardial infarction. Normal LBBB pattern.

References

  1. Sgarbossa EB. Value of the ECG in suspected acute myocardial infarction with left bundle branch block. J Electrocardiol. 2000;33 Suppl:87-92. DOI:10.1054/jelc.2000.20324 | PubMed ID:11265742 | HubMed [LBTB]
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