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 McCabe et al. JAHA, 2014 Case 1 65 y.o F with fatigue 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 65 y.o. F with the sugar diabetes BIBA w/ fatigue and vomiting for a few hours. Vital signs and physical exam are unremarkable 1
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 3 Questions 1. Is this LBBB? Case 1 65 y.o F with fatigue 2. Is this NEW LBBB? 3. Can we read ST segment abnormalities? 2
5/23/14 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 LBBB 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 3
2) Is this NEW LBBB? Predictive Value of New or Presumed New LBBB Indications for PCI and Thrombolytics 1mm ST elevation in 2 contiguous leads or Left Bundle Branch not known to be old 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 2) Is this NEW LBBB? Indications for PCI and Thrombolytics 1mm ST elevation in 2 contiguous leads or 2013 ACCF/AHA Guideline for the Management Left of Bundle ST-Elevation Branch Myocardial not known Infarction to be old 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 of ST-Elevation Myocardial Infarction Criteria for ECG diagnosis of acute STEMI in the setting of LBBB have been proposed (see Online Data Supplement 1) 4
LBBB Iso-electric or Discordant (ST segment opposite the terminal QRS) This is true for every lead ACUTE MI in LBBB ACUTE MI in LBBB CONCORDANT ST Elevation CONCORDANT ST Depression EXCESSIVE DISCONCORDANCE ST:S wave = 0.25 or more 5
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 6
1) 65 y.o. F with fatigue 1) 65 y.o F with fatigue baseline LBBB STEMI! 9 NOT STEMI! 3 28 22 Another pt with LBBB and Chest Pain 4 2 Yet another pt with LBBB and Chest Pain c 4 c 16 7
ACUTE MI in Paced Rhythms 80 y.o. M with CP and pacer Same as with LBBB! 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 8
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 Widen your knowledge and lighten your load! 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 9