Critical ECG: ACS Flashcards by Mark van Eijk

What is the significance of De Winter’s T-waves?

STEMI equivalent!
EARLY sign in development of an occlusive MI
Patient should receive close follow-up monitoring (serial 12-lead ECGs) and advocacy for cardiology consult

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Is the pattern seen here consistent with Wellen’s Type A, Type B, or neither?

Wellen’s Type A

Biphasic “uppy-downy” T-waves in V1-V3

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In which situations should a diagnosis of aVR STEMI be considered with extreme caution?

Significant tachycardia
- aVR STEMI pattern is common in significant tachycardia due to rate-related ischemia, and is unlikely to be due to infarction
Absence of signs/symptoms of ACS
- Consider other causes which may cause global hypoxia/ischemia (i.e. sepsis, respiratory failure, anemia, etc.)

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Are reciprocal changes considered in the current AHA guidelines for STEMI recognition?

NO!

Just look for 2 contiguous leads with >1.0mm STE (or more in V2/V3, age/sex dependent)

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Compare sensitivity and specificity of the Sgarbossa and Smith-modified criteria for AMI in the presence of LBBB/pacing

Sgarbossa criteria are Specific (96%) but non-sensitive (36%) for AMI
- This is largely due to the lack of sensitivity in Sgarbossa’s third criterion (excessive discordance)
Smith’s modified rule improves sensitivity substantially (91%) with a slight decrease in specificity (90%)

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Classify the ST changes shown in terms of:

Elevation/depression/neither

Concordant/discordant/neither

Concordant ST elevation

This is a STEMI until proven otherwise! (36% sensitivity, 90% specificity)

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De Winter’s T-waves are characterized by precordial ST elevation with inverted T-waves, true or false

FALSE!

This is the opposite of what is true…. DWTWs involve ST-DEPRESSION!

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Describe Smith’s modification to the Sgarbossa Criteria

Replaces Sgarbossa’s 3rd criterion (first 2 are unchanged) relating to excessively discordant ST elevation
Considers the ratio between the STE and the magnitude of the preceding S-wave
- If ST/S ratio is >0.25 in a lead with discordant STE (i.e. if the ST elevation is more than a quarter the size of the S-wave) then the complex is said to be smith-positive and AMI should be suspected
Improves the sensitivity (but not specificity) of the Sgarbossa criteria

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Is the pattern seen here consistent with Wellen’s Type A, Type B, or neither?

Wellen’s Type B

Deeply inverted symmetrical T-waves throughout precordial leads

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Is the pattern seen here consistent with Wellen’s Type A, Type B, or neither?

Neither!

These appear to be biphasic T-waves, but are negative-then-positive. Wellen’s type A is positivie-then-negative (uppy-downy).

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Classify the ST changes shown in terms of:

Elevation/depression/neither

Concordant/discordant/neither

If relevant, assess for excessive discordance by Sgarbossa’s original criteria and Smith’s modified criteria

Discordant ST elevation

This is excessive discordance both by Sgarbossa’s original criteria (STE >5mm) and by Smith’s modified criteria (ST/S ratio >0.25)

This is a STEMI until proven otherwise (>90% sensitivity AND specificity)

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What are the key criteria for recognizing De Winter’s T-waves on the 12-lead ECG?

J-Point depression with up-sloping ST segments.
Tall, prominent, symmetric T waves in the precordial leads.
- AKA “rocket-shaped” T waves
Upsloping ST segment depression > 1mm at the J-point in the precordial leads.
Absence of ST elevation in the precordial leads.
ST segment elevation (0.5mm-1mm) in aVR.

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Which leads may show relatively large ST-elevations, even at baseline?

V2 and V3

Have a higher threshold for ST-Elevation in these leads. >2.5mm in males younger than 40, >2.0mm in males older than 40, and >1.5mm in females. In all other leads, the threshold is 1.0mm

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In the context of LBBB, is excessively discordant (>5mm) ST elevation in a single lead sensitive or specific for AMI?

NO! Unless it is also Smith-positive (ST/S>0.25)!

Sgarbossa’s third criterion in isolation is neither sensitive nor specific for AMI

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Describe “appropriate discordance” in LBBB

ST elevation or depression is normal and expected in LBBB so long as it is in the OPPOSITE direction of the majority of the QRS complex (discordant), and is not excessive in magnitude
inappropriate, or “excessive” discordance is defined by the Smith-modified Sgarbossa criteria as:
- Discordant ST elevation >1/4 the magnitude of the preceding S wave
- alternatively stated as an ST/T ratio >0.25

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When are the Sgarbossa criteria applied?

Used to identify AMI in the setting of LBBB or a ventricular paced rhythm.
- These patterns typically have a baseline amount of ST-elevation, which may conceal AMI

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Classify the ST changes shown in terms of:

Elevation/depression/neither

Concordant/discordant/neither

Concordant ST Depression

This is a STEMI until proven otherwise (Sgarbossa’s 2nd criterion)

Is this rhythm appropriate for evaluation using Sgarbossa/Smith criteria?

If so, is there evidence for AMI?

If not, why not?

Yes! Ventricular paced rhythm’s may be assessed using the Sgarbossa/smith criteria, and will not be interpreted using the LP15 integrated software!

There is definitive evidence of AMI based on the concordant ST depression in the precordial leads (Sgarbossa II)

What are 5 STEMI mimics (i.e. 5 ECG patterns that cause non-ischemic ST elevation)

LBBB
Benign Early Repolarization (BER)
Pericarditis
Left Ventricular Hypertrophy (LVH)
Hyperkalemia

Decribe key 12-lead features of pericarditis

Widespread concave ST elevation and PR depression
- Reciprocal ST depression and PR elevation in lead aVR
- Measure baseline via TP Segment
- Sinus tachycardia is also common in acute pericarditis due to pain and/or pericardial effusion
Spodick’s sign, or a downsloping TP segment, seen in 80% of ECGs with pericarditis

Classify the ST changes shown in terms of:

Elevation/depression/neither

Concordant/discordant/neither

Discordant ST depression

Discordant ST depression is not a component of the Sgarbossa or Smith-modified criteria for AMI in LBBB

Describe key 12-lead features of aVR STEMI

Widespread horizontal ST depression (often I, II, aVL, and V4-6)
ST elevation in aVR ≥ 1mm
ST elevation in aVR ≥ V1
- STE in V1 > aVR is concerning for Brugada pattern

Describe key 12-lead features of LVH

LVH is assessed through voltage criteria and presence of a strain pattern

Voltage Criteria
- Magnitude of deepest S wave in V1/2 + tallest R wave in V5/6 > 35mm total
Strain pattern
- ST Elevation V1-4
- ST Depression / Inverted T waves V5 and V6
- Generally proceeds from most elevated V1/2 to most depressed V6
- Consider utilizing LP15 measurements to help identify

Describe similarities and differences between De Winter’s pattern and posterior STEMI pattern

Both are characterized by precordial ST depression with upright T-waves
Both are STEMI equivalents
The ST segment is horizontal in posterior STEMI, but upsloping in De Winter’s
There is often a dominant R-wave in V2 for posterior STEMI, whereas De Winter’s has a normal R-wave transition

What are the three types of occlusion/lesion associated with aVR STEMI?

* LMCA occlusion * Proximal LAD occlusion * Severe triple-vessel disease ## Footnote *The aVR STEMI pattern may also be associated with global or demand ischemia, and other reasonable differentials should be considered*

Describe Wellen's syndrome in terms of pathophysiology and patient presentation (not ECG findings).

* Refers to critical stenosis of the LAD (80-90%) which may be a warning sign for impending infarct * Usually diagnosed following the **resolution** of an episode of unstable angina (i.e. ECG findings generally only appear after pain has resolved)

Describe key 12-lead features of posterior STEMI

* Horizontal ST depression \>1mm in V1-V4 (sensitive) * Supporting characteristics * Tall, broad R-wave in suspect leads * Upright T-waves in suspect leads * Dominant R wave in V2 (early transition) * ST elevation in posterior leads (V7/8/9) adds specificity but is not required for Dx

Classify the ST changes shown in terms of: Elevation/depression/neither Concordant/discordant/neither If relevant, assess for excessive discordance by Sgarbossa's original criteria and Smith's modified criteria

Discordant ST elevation This is appropriate discordance, to be expected in LBBB and not indicative of ischemia. It does not satisfy Sgarbossa's original or Smith's modified criteria. *It is unlikely that this is a STEMI! Smith's modified criterion is 90% sensitive for STEMI in LBBB.*

Describe characteristics of benign early repolarization and age groups where this is an appropriate differential

* Benign ECG pattern mimicking STEMI * Often young healthy males and be found with concurrent chest pain. * Widespread concave ST elevation with J point elevation * May have 'fish-hooked' Osborne wave * No reciprocal ST depression to suggest STEMI (except in aVR) * ST changes are relatively stable over time (no progression on serial ECG tracings) * Common in males \<50 years old. Do not consider BER as a DDx for older males or females of any age.

Is it normal for De Winter's T-waves to resolve to a "normal" pattern with time?

Yes! ## Footnote *This is not necessarily a good sign! Dynamic changes are rarely favorable with suspected OMI. Get thee to a hospital!*

Discordant ST elevation This is excessive discordance by Smith's modified criteria (ST/S ratio \>0.25) but **NOT** by Sgarbossa's original criteria. This would have been a likely false *negative.* *This is a **STEMI** until proven otherwise (\>90% sensitivity AND specificity)*

Classify the ST changes shown in terms of: Elevation/depression/neither Concordant/discordant/neither

Concordant ST elevation ## Footnote *This is a **STEMI** until proven otherwise! (36% sensitivity, 90% specificity)*

What are the Original Sgarbossa Criteria?

* ST elevation ≥ 1 mm in a lead with upward (concordant) QRS complex * ANY concordant ST elevation is BADNESS * 5 pts * ST depression ≥ 1 mm in lead V1, V2, or V3 * PRECORDIAL concordant ST Depression is BADNESS * 3 pts * ST elevation ≥ 5 mm in a lead with downward (discordant) QRS * EXCESSIVE discordant ST elevation is perhaps badness * 2 pts ≥ 3 points = 90% specificity of STEMI (sensitivity of 36%)

Will the LP15's algorithm automatically apply the Sgarbossa criteria to LBBB? What about ventricular paced rhythms? Will it apply the Smith's-modified criteria?

* The LP15 will automatically apply Sgarbossa's criteria to LBBB only * Sgarbossa's criteria are not applied to ventricular paced rhythms, and this should be done manually * The LP15 uses the original Sgarbossa Criteria (not Smith's modified)

What is the ECG pattern shown in this image? What is its significance?

De Winter's T-wave * STEMI equivalent! * EARLY sign in development of an occlusive MI * Patient should receive close follow-up monitoring (serial 12-lead ECGs) and advocacy for cardiology consult

How long should you wait after ROSC to perform a 12-lead? Why?

5-10 minutes (BCEHS post-arrest checklist) to allow for reperfusion and avoid false positives

Classify the ST changes shown in terms of: Elevation/depression/neither Concordant/discordant/neither

Discordant ST depression *This is NOT concordant depression! Concordance/discordance is determined based on the DOMINANT deflection of the QRS, not the terminal deflection. In this case, even though the QRS ends up negative, it is _mostly_ positive, making the ST depression discordant.*

Differentiate between type A and type B T-wave patterns in Wellen's syndrome

Type A: Biphasic T-waves in the precordial leads (usually V2/V3) that are first positive, then negative (uppy downy) Type B: Deeply inverted T-waves in V1-V4

What 5 ECG patterns are considered STEMI equivalents?

* De Winter's T-waves * Wellen's Syndrome * LBBB with positive Sgarbossa criteria (Smith's modified preferred) * aVR STEMI * Posterior STEMI

The magnitude of ST elevation in aVR STEMI _______ (is/isn't) associated with the probability of mortality

IS! * STE in aVR ≥ 0.5mm was associated with a 4-fold increase in mortality * STE in aVR ≥ 1mm was associated with a 6- to 7-fold increase in mortality * STE in aVR ≥ 1.5mm has been associated with mortalities ranging from 20-75%

What are the current AHA (and BCEHS) guidelines for STEMI recognition? ## Footnote *Not including "STEMI equivalents"*

ST-elevation in 2 anatomically contiguous leads measuring: * Men \< 40 years of age: 2.5 mm in V2-V3 and 1 mm in all other leads * Men ≥ 40 years of age: 2 mm in V2-V3 and 1 mm in all other leads * Women: 1.5 mm in V2-V3 and 1 mm in all other leads