Goals: Widen Your Understanding of the Wide QRS! 1. Describe an - - PDF document

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Goals: Widen Your Understanding of the Wide QRS!

• 1. Describe an approach to diagnosis of

LBBB

• 2. Describe the predictive

value of New LBBB

• 3. Describe the ST

segment changes that are diagnostic of AMI in LBBB

• “Based on the ECG above, is there a

blocked coronary artery present causing a STEMI?”

• 36 STEMI activations

– Overall 65% sensitivity, 79% specificity – No difference in accuracy between EP’s, Cardiologists, Interventional Cardiologists – Years of experience was only predictor of accuracy McCabe et al. JAHA, 2014

Case 1 65 y.o F with fatigue

• 65 y.o. F with the sugar diabetes BIBA w/

fatigue and vomiting for a few hours.

• Vital signs and physical exam are

unremarkable

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1) 65 y.o. F with fatigue

Case 1 65 y.o F with fatigue

• No Old ECG available
• Called for records to another hospital

and faxed consent

• While awaiting response, patient went

into Vfib, was resuscitated, rushed to cath and found to have 100% LAD

Case 1 65 y.o F with fatigue

3 Questions

• 1. Is this LBBB?
• 2. Is this NEW LBBB?
• 3. Can we read ST segment abnormalities?

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• The QRS is wide, usually > 0.14
• Look at TERMINAL QRS wave in Lead V1

and Lead 1 (V6)

• LBBB = Terminal R in 1 (V6) and Slurred S in V1

Left Bundle Branch Man

• Left hand is up for LBBB
• Left hand represents left side - lateral leads
• Right hand represents right side – V1
• Hand points in direction of the final wave of the

QRS (i.e. R wave points up, Q and S waves point down

LBBB

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2) Is this NEW LBBB?

Indications for PCI and Thrombolytics

• 1mm ST elevation in 2 contiguous leads
• r
• Left Bundle Branch not known to be old

Predictive Value of New or Presumed New LBBB

Chang, Am JEM, 2009

• 55 with New LBBB = 7.3% AMI
• 136 with Old LBBB = 5.2% AMI
• 7746 with no LBBB = 6.1% AMI

New LBBB is not predictive of AMI Indications for PCI and Thrombolytics

• 1mm ST elevation in 2 contiguous leads
• r
• Left Bundle Branch not known to be old

2) Is this NEW LBBB?

2013 ACCF/AHA Guideline for the Management

• f ST-Elevation Myocardial Infarction

“New or presumably new LBBB at presentation occurs infrequently, may interfere with ST-elevation analysis, and should not be considered diagnostic of acute MI in isolation.”

3) Can we read the ST segments (i.e. Dx AMI) in LBBB?

2013 ACCF/AHA Guideline for the Management

• f ST-Elevation Myocardial Infarction
• Criteria for ECG diagnosis of acute STEMI in

the setting of LBBB have been proposed (see Online Data Supplement 1)

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• Iso-electric or
• Discordant (ST segment opposite the terminal QRS)
• This is true for

every lead

LBBB ACUTE MI in LBBB

CONCORDANT ST Elevation CONCORDANT ST Depression

ACUTE MI in LBBB

EXCESSIVE DISCONCORDANCE ST:S wave = 0.25 or more

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Acute MI in LBBB

Annals of EM, October 2008

Acute MI in LBBB

• 1 mm Concordant ST elevation

– 10 studies with 1,614 patients – Sensitivity = 20% (NLR = 0.8) – Specificity of 98% (PLR = 7.9)

• 5 mm Discordant ST elevation

– Specificity of 80% (PLR = 4.5)

Acute MI in LBBB

Annals of EM, August 2012

ST segments in AMI/LBBB

• Excessive Discordance

– ST elevation: S wave >= 1:4 – ST depression: R wave >= 1:4 – Significant improvement in sensitivity and specificity

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1) 65 y.o. F with fatigue

28 9

STEMI! 1) 65 y.o F with fatigue – baseline LBBB

22 3

NOT STEMI! Another pt with LBBB and Chest Pain

c

4 16 2 4

Yet another pt with LBBB and Chest Pain

c

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ACUTE MI in Paced Rhythms

• Same as with LBBB!

80 y.o. M with CP and pacer Prior ECG Take Home Points Dx of AMI in LBBB

• 1. Determine if LBBB

– LBBB man

• 2. Do not use New LBBB to predict AMI

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Take Home Points Dx of AMI in LBBB

• 3. Determine if AMI is present

Expected ST segments – Opposite terminal R or S wave – or isoelectric – in every lead

Take Home Points Dx of AMI in LBBB

• 3. Determine if AMI is present

Acute MI

• 1 mm Concordant ST segments (in same direction

as last wave of QRS) in any lead

• Excessive Discordance of ST segments (opposite

to terminal R or S wave) – ST:S wave ratio > = 1:4

Treatment of Chest Pain with LBBB or a Paced Rhythm

• If ST changes diagnostic of AMI then

– Reperfuse immediately (Lytics or Cath Lab) if

• If no concerning ST changes then

– Involve cardiology consultant early if possible – Reperfuse for high suspicion of STEMI (> 50%?) – Use cardiac markers or formal echo to rule out AMI in the rest

Widen your knowledge and lighten your load!