ECG Case 045

64-year old female presenting with severe chest pain and diaphoresis. Describe the ECG

TOP 100 ECG QUIZ LITFL 045

Describe and interpret this ECG

ECG ANSWER and INTERPRETATION

This ECG shows a ventricular paced rhythm with positive Sgarbossa criteria:

  • There is concordant ST depression in V2-5. This violates the expected pattern of discordance for a V-paced rhythm and is a marker of superimposed myocardial infarction.
  • The morphology in V2-5 is reminiscent of posterior STEMI, with horizontal ST depression and prominent upright T waves.
  • Multiple non-conducted P waves are seen, indicating the presence of underlying high-grade AV block (probably the indication for pacemaker insertion). However, the fusion complex (beat #5 on rhythm strip) suggests that P waves are occasionally transmitted, arguing against complete heart block.

This patient did indeed have an isolated posterior infarction, due to complete occlusion of a posterolateral branch of the RCA. She was successfully treated with PCI.


CLINICAL PEARLS

Sgarbossa Criteria

These criteria allow for detection of myocardial infarction in patients with LBBB and V-paced rhythms (previously thought to be “impossible”).

Normal Pattern in LBBB / VPR

The expected finding in patients with uncomplicated LBBB / V-paced rhythm is discordance — i.e. the ST segments and T waves point in the opposite direction to the QRS complex.

Sgarbossa Criteria ECG discordant ST segments and T waves
ECGMedicalTraining.com with permission.

How To Spot Superimposed MI

Superimposed myocardial infarction is suspected if there is either:

  • Loss of the usual pattern of discordance — i.e. concordant ST changes.
  • Excessive discordant ST elevation — i.e. out of proportion to what would be expected for LBBB / paced rhythm.
Sgarbossa Criteria ECG LBBB Paced rhythm
ECGMedicalTraining.com with permission.

Sgarbossa Criteria

Diagnosis of MI in LBBB / VPR requires at least one of the following criteria to be present:

  • Concordant ST depression > 1 mm in V1-3.
  • Concordant ST elevation > 1 mm in any lead.
  • Excessively discordant ST elevation in any lead >5 mm (original Sgarbossa criteria) or >25% of the corresponding S-wave depth (modified Sgarbossa criteria = more specific).

Changes only have to be present in a single lead to be diagnostic of MI.


TOP 100 ECG SERIES


Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

One comment

  1. Ahmed Abdulkarim
    Ahmed Abdulkarim

    thanks a lot for this nice ECG with great explanation but i will argue with that, the ectopic beat wasn’t a fusion beat, instead it’s premature ventricular contraction. The evidence of that are QRS occurred prematurely and the PPM is programmed to pace every 5 seconds. there is also no spike preceding the QRS. so its PVC and the heart block is complete

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