12 Lead

Current Concepts

Dana$Yost,$Senior$Paramedic$Paramedic$Training$King$County,$WA$

Appropriate Cardiac Cath Lab activation: Optimizingelectrocardiogram interpretation and clinical decision-making for acute ST-elevation myocardial infarctionIvanC. Rokos,MD,a William J. French,MD,b AmalMattu,MD,c GrahamNichol,MD,dMichael E. Farkouh,MD,MSc,e

James Reiffel, MD,f and Gregg W. Stone, MDf Los Angeles, CA; Baltimore, MD; Seattle, WA; Toronto, ON; andNew York, NY

During the last few decades, acute ST-elevation on an electrocardiogram (ECG) in the proper clinical context has been a reliablesurrogate marker of acute coronary occlusion requiring primary percutaneous coronary intervention (PPCI). In 2004, theAmerican College of Cardiology/American Heart Association ST-elevation myocardial infarction (STEMI) guidelines specifiedECG criteria that warrant immediate angiography in patients who are candidates for primary PPCI, but new findings haveemerged that suggest a reappraisal is warranted. Furthermore, as part of integrated and efficient STEMI systems, emergencydepartment and emergency medical services providers are now encouraged to routinely make the time-sensitive diagnosis ofSTEMI and promptly activate the cardiac catheterization laboratory (Cath Lab) team. Our primary objective is to provide apractical summary of updated ECG criteria for emergency coronary angiography with planned PPCI, thus allowing clinicians tomaximize the rate of appropriateCath Lab activation and minimize the rate of inappropriateCath Lab activation.We review theevidence for ECG interpretation strategies that either increase diagnostic specificity for “classic” STEMI and left bundle-branch block or improve diagnostic sensitivity in identifying 4 STEMI-equivalents: posterior MI, acute left main occlusion, deWinter ST/T-wave complex, and certain scenarios of resuscitated cardiac arrest. (Am Heart J 2010;160:995-1003.e8.)

The key trigger point for emergency cardiac catheter-ization laboratory (Cath Lab) activation is usually a singleelectrocardiogram (ECG) diagnostic of an acute ST--elevation myocardial infarction (STEMI), which instantlyreclassifies a patient with chest pain or other acutecardiac symptoms from “routine evaluation” status to“high-priority” STEMI procedure (Figure 1). The 2004American College of Cardiology/American Heart Associ-ation (ACC/AHA) guidelines1 specify ECG criteria thatwarrant immediate angiography in patients who arecandidates for primary percutaneous coronary interven-tion (PPCI). Although new findings related to the ECG

diagnosis of STEMI have emerged since 2004, they havenot been reviewed by any of the more recent guide-lines.2-6 Hence, our primary objective is to provide apractical summary of updated criteria for emergencycoronary angiography with planned PPCI, thus allowingclinicians to maximize the rate of appropriate Cath Labactivation and minimize the rate of inappropriate CathLab activation.Three background concepts are important. First, ECG

analysis is a fundamental clinical skill that is usedroutinely by a broad range of clinicians, but high-riskECG findings consistent with acute ischemia continue tobe overlooked.7 Second, a common “efficiency chal-lenge” involves the need to quickly differentiate and treatthe small cohort of acute STEMI patients from the muchlarger group of undifferentiated “chest pain” patients(Figure 1). This must be balanced against the potential forpoor resource utilization, especially with the currentemphasis on early Cath Lab activation by either emer-gency department (ED) or emergency medical servicesproviders.8,9 Third, a coordinated systems-based ap-proach is currently emphasized by the ACC/AHA STEMIguidelines,2,3 the ACC Door-2-Balloon (D2B) Alliance,10

and the AHA Mission: Lifeline initiative.11 Proposedefforts within Mission:Lifeline12 to comprehensivelytrack all Cath Lab activations and improve overall STEMIsystem efficiency depend on the existence of clearly

From the aUCLA-Olive View, Department of Emergency Medicine, Los Angeles, CA,bHarbor-UCLA, Division of Cardiology, Department of Medicine, Los Angeles, CA,cUniversity of Maryland, Department of Emergency Medicine, Baltimore, MD, dUniversityof Washington-Harborview Center for Pre-Hospital Emergency Care, Seattle, WA,eUniversity Health Network and Li Ka Shing Knowledge Institute, Toronto, ON, andfColumbia University Medical Center and the Cardiovascular, Research Foundation,New York, NY.Submitted March 29, 2010; accepted August 12, 2010.Reprint requests: Ivan C. Rokos, MD, FACEP, FAHA, (FACC), UCLA-Olive View MedicalCenter, Department of Emergency Medicine, North Annex, 14445 Olive View Drive,Sylmar, CA 91342-1495.E-mail: irokos@earthlink.net0002-8703/$ - see front matter© 2010, Mosby, Inc. All rights reserved.doi:10.1016/j.ahj.2010.08.011

Curriculum in Cardiology

American Heart Journal Dec 2010

Table I. Comparison of 2004 ACC/AHA guidelines and authors' proposed update for ECG criteria that enhance the rate of appropriate CathLab activation for acute MI

Indications forappropriate CathLab activation

Diagnostic criteria forpatients with

symptoms <12 h

2004 ACC/AHAguideline

recommendationProposed update vs.ACC/AHA guidelines Comment

Classic STEMIAnterior ST-elevation !1 mm in 2

contiguous leads V1-V4

Class I-A Agree ST-elevation !2 mm (men)and !1.5 mm (women)improves diagnosticspecificity.15

Presence of reciprocalchanges (ST-depression inopposite leads) improvesdiagnostic specificity.

Inferior ST-elevation !1 mm in 2contiguous leads(II, III, or AVF)

Class I-A Agree Presence of reciprocalchanges improves diagnosticspecificity.

Lateral ST-elevation !1 mm in 2contiguous leads(I, AVL, V5, or V6)

Class I-A Agree As above.

STEMI-equivalentsNew or presumednew-onset LBBB

“Presumed new” LBBBassumed when priorECG unavailable”“New” LBBB when priorECG available

Class I-A Proposed demotion in futureACC/AHA guidelines

Unless clinically unstable,most LBBB should beevaluated with biomarkersand non-emergentangiography if indicated.An “old” ECG without LBBBdoes not necessarily confirmthat the “new LBBB” is acute.

Preexisting LBBB withSgarbossa concordance

Concordance noted betweenQRS complex and ST/T-wavecomplex, with ST elevation!1 mm in !1 lead

None Proposed addition to futureACC/AHA guidelines

Use of these decision criteriaprovides N95% specificityand avoids the need to find aprior ECG for comparison.Discordant ST-elevation! 5 mm is also a Sgarbossacriteria, but some studiesfound it a weak predictor.

Posterior MI (isolated) ST-depression !0.5 mm inleads V1-V3Associated T-waves are eitherupright or inverted.Appearance of tall R-wavesin V1-V2 may be delayed.

Fibrinolytics: class IIa-CPrimary PCI: class I-A implied

Proposed clarification infuture ACC/AHA guidelines

Recent data34 demonstratedthat most posterior MIs arecurrently evaluated withurgent (rather thanemergent) angiography, butthis delay is associated withworse clinical outcomes.

Left Main coronaryocclusion

ST-depression ! 1 mm in6 or more leadsLeadaVRwithST-elevation!1mmST-elevation in lead aVR !V1

None Proposed addition to futureACC/AHA guidelines

Most relevant in any ECGwith diffuse ST-depression!1 mm that does not meetclassic STEMI criteria, thusproviding a subtle clue thatemergency angiographymay be warranted

de Winter ST/T-wavecomplex

ST depression !1 mmup-sloping at the J-point inleads V1-V6

None Proposed addition to futureACC/AHA guidelines

Tall T waves and up-slopingST depression are persistent,not transient.

Precordial T waves are tall,upright, symmetricNormal QRS duration

Associated with proximalLAD occlusion

Hyper-acute T-waves Tall peaked T wavesimmediately followingsymptom onset mayrepresent acute ischemia,but clinical studiesare lacking.

None Potential addition to futureACC/AHA guidelines

Generally prudent to performserial ECGs, because trueHATW generally morphquickly into a classic STEMIpattern13

Hyperkalemia is anothercommon cause of tall T waves

Rokos et al 997American Heart JournalVolume 160, Number 6

Table I. Comparison of 2004 ACC/AHA guidelines and authors' proposed update for ECG criteria that enhance the rate of appropriate CathLab activation for acute MI

Indications forappropriate CathLab activation

Diagnostic criteria forpatients with

symptoms <12 h

2004 ACC/AHAguideline

recommendationProposed update vs.ACC/AHA guidelines Comment

Classic STEMIAnterior ST-elevation !1 mm in 2

contiguous leads V1-V4

Class I-A Agree ST-elevation !2 mm (men)and !1.5 mm (women)improves diagnosticspecificity.15

Presence of reciprocalchanges (ST-depression inopposite leads) improvesdiagnostic specificity.

Inferior ST-elevation !1 mm in 2contiguous leads(II, III, or AVF)

Class I-A Agree Presence of reciprocalchanges improves diagnosticspecificity.

Lateral ST-elevation !1 mm in 2contiguous leads(I, AVL, V5, or V6)

Class I-A Agree As above.

STEMI-equivalentsNew or presumednew-onset LBBB

“Presumed new” LBBBassumed when priorECG unavailable”“New” LBBB when priorECG available

Class I-A Proposed demotion in futureACC/AHA guidelines

Unless clinically unstable,most LBBB should beevaluated with biomarkersand non-emergentangiography if indicated.An “old” ECG without LBBBdoes not necessarily confirmthat the “new LBBB” is acute.

Preexisting LBBB withSgarbossa concordance

Concordance noted betweenQRS complex and ST/T-wavecomplex, with ST elevation!1 mm in !1 lead

None Proposed addition to futureACC/AHA guidelines

Use of these decision criteriaprovides N95% specificityand avoids the need to find aprior ECG for comparison.Discordant ST-elevation! 5 mm is also a Sgarbossacriteria, but some studiesfound it a weak predictor.

Posterior MI (isolated) ST-depression !0.5 mm inleads V1-V3Associated T-waves are eitherupright or inverted.Appearance of tall R-wavesin V1-V2 may be delayed.

Fibrinolytics: class IIa-CPrimary PCI: class I-A implied

Proposed clarification infuture ACC/AHA guidelines

Recent data34 demonstratedthat most posterior MIs arecurrently evaluated withurgent (rather thanemergent) angiography, butthis delay is associated withworse clinical outcomes.

Left Main coronaryocclusion

ST-depression ! 1 mm in6 or more leadsLeadaVRwithST-elevation!1mmST-elevation in lead aVR !V1

None Proposed addition to futureACC/AHA guidelines

Most relevant in any ECGwith diffuse ST-depression!1 mm that does not meetclassic STEMI criteria, thusproviding a subtle clue thatemergency angiographymay be warranted

de Winter ST/T-wavecomplex

ST depression !1 mmup-sloping at the J-point inleads V1-V6

None Proposed addition to futureACC/AHA guidelines

Tall T waves and up-slopingST depression are persistent,not transient.

Precordial T waves are tall,upright, symmetricNormal QRS duration

Associated with proximalLAD occlusion

Hyper-acute T-waves Tall peaked T wavesimmediately followingsymptom onset mayrepresent acute ischemia,but clinical studiesare lacking.

None Potential addition to futureACC/AHA guidelines

Generally prudent to performserial ECGs, because trueHATW generally morphquickly into a classic STEMIpattern13

Hyperkalemia is anothercommon cause of tall T waves

Rokos et al 997American Heart JournalVolume 160, Number 6

LBBB = Discordance or

Paced Rhythms = Discordance or

LBBB w/ Concordance !!! or

Paced Rhythm w/ Concordance !!! or

Isolated Posterior MI

LMCAO

Wellen�s Syndrome

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Wellen�s Syndrome

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Saturday, October 13, 20128:59 PM

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DeWinter T waves

Brugada Syndrome

Brugada Syndrome

Brugada Syndrome Saturday, October 13, 20129:42 PM

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Brugada Syndrome

Brugada Syndrome Saturday, October 13, 20129:42 PM

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Saturday, October 13, 20129:42 PM

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Tachycardia S1 Q3 T3 (IRBBB)

Tachycardia S1 Q3 T3 (IRBBB)

12-Lead 1Name:Patient ID:Incident ID:

ZENTER, JILL Device:Device Configuration:Software Revision:

LP15 MEDIC 35 LP15381912340L355RO402B9OR3306808-005

LIFENET® Report Renderer (5.1.4.1) Page: 1 of 1

Name:ID:

Age: 37

12-Lead 110/15/2012PR 0.142sQT/QTc:P-QRS-T Axes:

ZENTER,JILL101512182201

Patient ID:Incident ID:

Sex: F

18:26:11HR 116bpm

QRS 0.102s0.324s/0.422s54° -12° -20°

•  Abnormal  ECG  **Unconfirmed**•  Sinus  tachycardia•  rSr'(V1)  -­  probable  normal  variant•  Possible  inferior  infarct  -­  age  undetermined•  Anterolateral  ST-­T  abnormality   is  borderline   for  age  and  gender

I

II

III

aVR

aVL

aVF

V1

V2

V3

V4

V5

V6

x1.0 .05-150Hz 25mm/secPhysio-Control, Inc. Comments:

MEDIC 35 M35 3306808-005 LP1538191234

ST measurements are measured at the J point and are expressed in mm.

I-0.49

II-0.47

III0.02

aVR0.49

aVL-0.26

aVF-0.23

V10.26

V20.04

V3-0.26

V4-0.40

V5-0.42

V6-0.41

To ensure printer accuracy, confirm that the calibration markers are 10mm high and the grid squares are 5mm wide.

Summary

!  Use a systematic approach to interpretation

!  Recognize Concordance in LBBB and Pacer

!  Recognize: !  Posterior !  LMCAO !  Wellen�s Syndrome !  DeWinters !  Brugada Syndrome !  PE