Sgarbossa Criteria

Read this ECG:

Anterior STEMI

Let’s look through this together. We recommend using a systematic approach to every ECG: Rate, Rhythm, Axis, Intervals, Hypertrophy, Ischemia/Infarct.

Rate: 60 bpm.

Rhythm: p waves appear regular morphology, upright ,and proceeding every QRS. But we note that the QRS complex appears broad suggesting a ventricular origin and if you look closely, you’ll note a “spike” proceeding QRS complex (look at aVL, aVF, V1-3). This suggest a pacemaker lead is present leading to a ventricularly-paced rhythm.

Axis: + in leads I, II - normal axis.

Intervals: PR <200 ms. QRS complex appears broad (>120ms) and looking at V1-3 we see typical LBBB pattern common to v-paced rhythms. QT is not prolonged.

Here’s this patients prior ECG (below) more clearly demonstrating the ventricular pacing. Note the pace spikes prior to each QRS.

baseline ECG

Also note the patient’s ST segments in V1-3 on the baseline ECG. He has ST elevation and positive T waves associated with his qS complex as the LBBB. This makes diagnosing any acute ischemia within a LBBB difficult.

Before we can review the current ECG for Ischemia/Infarct, we must to acknowledge the expected “appropriate discordance” in LBBB. Meaning that the T wave should deflect in the opposite direction of the QRS.

In a negative QRS, the T wave will deflect in the positive direction (discordance).

T wave deflection in the same direction of QRS complex is concordance.

Sgarbossa Criteria

The original Sgarbossa criteria used to diagnose ischemia in patients with a LBBB:

A total score of ≥ 3 is reported to have a specificity of 90% for diagnosing myocardial infarction. These criteria are not very sensitive.

Our patient’s ECG shows discordant ST-segment elevation > 5 mm in leads V2 and V3 (criterion #3) and concordant ST-segment elevation > 1 mm in lead V4 (criterion #1) which earned him 7 points. He was taken for coronary angiography finding 90% stenosis of his mid-LAD and underwent stenting.

The Modified Sgarbossa Criteria was established to improve the diagnostic accuracy by replacing criterion #3 (an arbitrary cut off of 5 mm) with an ST:S ratio. This criteria does not use a point system; instead, presence of any 1 of 3 criteria is considered positive for ischemia.

SOURCE: HTTPS://ECGWAVES.COM/TOPIC/LEFT-BUNDLE-BRANCH-BLOCK-ACUTE-CORONARY-SYNDROMES-SGARBOSSA