Chest pain, left bundle branch block, and excessively discordant ST-segment elevation

62 year old male presents to the emergency department complaining of chest discomfort.

Past medical history is significant for dyslipidemia and ulcerative colitis. Also prior history of significant tobacco use.

Maternal history of CAD. Maternal and paternal history of stroke.

The patient’s only medication is Lipitor but he took an aspinin en route to the hospital.

  • Onset: Patient states the pain started that morning and became progressively worse since lunch time
  • Provoke: Nothing makes the pain better or worse
  • Quality: Sharp and non-pleuritic
  • Radiate: The pain radiates down the right arm to the bicep
  • Severity: 7/10
  • Time: Patient states he experienced a similar pain in his right upper chest several days prior while playing tennis. He stopped exercising and the pain resolved.

The pain makes the patient feel “a little clammy.” He denies shortness of breath. He states that he feels “a little dizzy” but denies palpitations. He had a negative stress test 3-4 years ago.

He has a known history of left bundle branch block.

The patient’s skin is warm and dry.

Breath sounds are clear bilaterally. No JVD. Neuro exam normal.

Vital signs

  • RR: 18
  • HR: 60
  • NIBP: 140/72
  • SpO2: 98% on room air

A 12-lead ECG is captured and presented to the ED physician within 5 minutes of arrival.


Sinus rhythm and left bundle branch block. There is discordant ST-segment elevation in the anterior leads but is it excessively discordant? Could this be LAD occlusion?

An “old” ECG is retrieved from the computer system for comparison.



The “old” ECG shows far less ST-segment elevation in the anterior leads.

After oxygen and nitroglycerin the patient reports a significant decrease in pain.

An additional 12-lead ECG is obtained.


There is slightly less ST-segment elevation in leads V3 and V4 but this is still abnormal when compared to the old ECG.

serial ecgs

Generally speaking, secondary ST/T wave abnormalities (as opposed to the primary ST/T wave changes associated with ischemia) should not improve with oxygen and nitroglycerin.

Dynamic ST/T-wave changes usually (but not always) suggest the dynamic myocardial oxygen supply vs. demand characteristics of ACS.

Now, let’s go back to the initial 12-lead ECG. Is the ST-elevation in the anterior leads cause for concern?

Smith’s modification to Sgarbossa’s criteria indicates that ST-segment elevation in left bundle branch block, measured at the J-point, should be no more than 0.25 the depth of the S-wave.

Using that criterion, how does this ECG measure up? Let’s take a look.

smith modification to sgarbossa criteria

The patient was ultimately sent to the cardiac cath lab where angiography revealed 100% occlusion of the LAD.

Further Reading

New left bundle branch block (LBBB) and dyspnea at Dr. Smith’s ECG Blog

Identifying Acute STEMI in the Presence of Paced Rhythm at JEMS

Making Sense of Sgarbossa’s Criteria – Chest Pain and Left Bundle Branch Block at ECG Medical Training


Meyers H, Limkakeng A, Jaffa E et al. Validation of the modified Sgarbossa criteria for acute coronary occlusion in the setting of left bundle branch block: A retrospective case-control study. American Heart Journal. 2015;170(6):1255-1264. doi:10.1016/j.ahj.2015.09.005.

Cai Q, Mehta N, Sgarbossa E et al. The left bundle-branch block puzzle in the 2013 ST-elevation myocardial infarction guideline: From falsely declaring emergency to denying reperfusion in a high-risk population. Are the Sgarbossa Criteria ready for prime time?. American Heart Journal. 2013;166(3):409-413. doi:10.1016/j.ahj.2013.03.032.

Smith S, Dodd K, Henry T, Dvorak D, Pearce L. 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 (PDF). Annals of Emergency Medicine. 2012;60(6):766-776. doi:10.1016/j.annemergmed.2012.07.119.

Updated: 03/31/2016

1 Comment

  • Terry says:

    Thanks Tom this Sgarbossa criteria has been a real eye opener for me. Can't tell you how many times I have said or been told you can't dx an MI with a BBB or all new LBBB is an MI until proven otherwise. Keep up the good work.

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