ecg and coronary angiogram correlation

590 Indian Journal of Clinical Practice, Vol. 23, No. 10 March 2013

cArdiology

ECG: A Simple Noninvasive Tool to Localize Culprit Vessel Occlusion Site in Acute STEMI BiplAB ghosh*, mAnoj indurkAr**, mAhendrA kumAr jAin

AbStRACt

Introduction:Variouselectrocardiogram (ECG)patterns candetermine the siteofocclusion in culprit coronaryartery in ST-elevation myocardial infarction (STEMI) and the size of the myocardium that is jeopardized. Objectives: The aim of this study was to assess diagnostic accuracy of the ECG localization of culprit vessel occlusion site as compared to coronary angiographic findings.Material and methods:ECGcriteriaforlocalizationofculpritvesselocclusionsitewerespecifiedandpatientswithSTEMI(n=21)weredividedintothreegroups:GroupsI,IIandIII,accordingtothelocalizationofculpritvesselocclusionsiteinleftanteriordescending(LAD),rightcoronaryartery(RCA)andleftcircumflex(LCx)coronaryarteries,respectively.GroupI wasfurtherdividedintofoursubgroups:Ia,Ib,IcandIb+caccordingtowhetherocclusioninLADwasproximaltobothfirstseptal (S1)andfirstdiagonal(D1) branches, distal to S1 but proximal to D1 branches, distal to both S1 and D1 branches or distal to S1branch,respectively.GroupIIwasfurtherdividedintotwosubgroups:IIaandIIbaccordingtowhetherocclusioninRCAwas proximal or distal to RV branch, respectively. The results of coronary angiograms were compared with those predicted by ECG. Results: The positive predictive accuracy (PPA) and negative predictive accuracy (NPA) of ECG criteria for LAD, RCA and LCxcoronaryarterieswere90.91%and100%,90%and100%,andundeterminedand90.48%,respectively.Amongsubgroups,thesensitivityofECGcriteriawasmaximumforgroupsIb+candIIb(100%)followedbyGroupIIa(71.43%),GroupIc(50%),Group Ia (42.86%)and least forGroup Ib (0%).The specificitywasmaximumforGroups Iaand IIa (92.86%) followedby GroupIb(90%),GroupIIb(89.47%),GroupIc(78.95%)andGroupIb+c(77.78%)inthatorder.ThePPAandNPAforGroupsIa,Ib,Ic,Ib+c,IIaandIIbwere75%and76.47%,0%and94.74%,20%and93.75%,42.86%and100%,83.33%and86.67%and50%and 100%, respectively. Conclusion: The present study demonstrates that ECG is an easily and widely available inexpensive tool to localize site of occlusion in culprit vessel in acute STEMI.

keywords: Culprit vessels, STEMI, ECG, coronary angiography

The standard 12 lead electrocardiogram (ECG) has long been a reliable clinical tool for diagnosis of acute myocardial infarction (AMI). SpecificECG patterns for the site of occlusion in culpritcoronary artery has been well-recognized.1 Larger the areaat risk,moreaggressiveshouldbe theattempt torestore or improve perfusion of that area.

objeCtIVeS

The aim of this study was to amalgamate various ECG criteria for localization of culprit vessel occlusion site

and to assess its diagnostic accuracy as compared to follow-upcoronaryangiographicfindings.

MAteRIAl AnD MetHoDS

ThepresentstudywascarriedoutonpatientsadmittedwithAMI after application of the following exclusioncriteria: Patients with history of previous myocardialinfarction and previous coronary artery bypass graft(CABG) surgery; ECG evidence of left bundle branchblock(LBBB),pre-excitationandpacedrhythm.Writteninformed consent was obtained from each patient. AMI was diagnosed as per standard criteria.1 A detailed history and physical examination was carried out. ECG was recorded on admission and then 90 minutes and three hours after completion of thrombolysis, and ifthrombolysiswasnotdone,atfourhoursand24hoursafter admission.Besides theseECGwasalso recordedwhenever symptoms and clinical situations demanded so. In inferior wall, AMI right sided leads and posterior leads were also recorded. Patients were referred to other hospitals for coronary angiography and the results were noted on subsequent follow-up. A lesion

*Senior ResidentDept. of Nephrology, Institute of Medical SciencesBanaras Hindu University, Varanasi, Uttar Pradesh**Associate ProfessorProfessorDept. of Medicine, Shyam Shah Medical CollegeRewa, Madhya PradeshAddress for correspondence Dr Biplab GhoshSenior residentDept. of Nephrology, Institute of Medical SciencesBanaras Hindu University, Varanasi - 221 005, Uttar PradeshE-mail: [email protected]

591Indian Journal of Clinical Practice, Vol. 23, No. 10 March 2013

CardIology

Criteria Occlusion site1. Any one or more of the following Proximal to S1 i. Complete RBBB ii. ST V1 > 2.5 mm iii. ST aVR iv. ST V5 v. New onset LAHB2. Q in aVL Proximal to D13. Any one or more of the following Proximal to S1

and/or D1 i. ST II 1.0 mm ii. Maximum ST appeared in V24. Q in V5 Distal to S15. ST aVL Distal to D16. No ST III Distal to S1 and/or D1Group Ia had criteria 1, 2 and 3; Group Ib had criteria 2 and 4 without 1 and 5; Group Ic had criteria 4, 5, and 6; Group Ib+c was the combination of Group Ib and Ic.

ECG Criteria to Identify Site of Occlusion in LAD (in AWMI)

Criteria RCA lCx*1. ST III > ST II Present Absent*2. ST aVL > ST I Present Absent*3. ST V3/ST III ratio 1.24. Lead V4R T-wave upright Inverted

T-wave5. ST V1-V2 Absent (present in

occlusion of dominant RCA causing posterior

wall MI)

Present

6. Max ST V2-V3 Absent Present7. ST V7-V9 Absent (present if RCA

dominant)Present

*In case of discrepancy between criteria 1, 2 and 3, the localization was done as per criteria 1 and 2 rather than 3. Criteria 5 to 7 were used mainly for supportive evidence.

ECG Criteria to Identify whether Site of Occlusion is in RCA or LCx (in IWMI)

Criteria Proximal to RV branch

Distal to RV branch

V4R ST 1 mm No ST ST V1 Present AbsentST VR > ST in V1-V3

Present Absent

Ratio of ST V3/ST III

< 0.5 >0.5, but


CardIology

Table 1. Demographic, Clinical and Laboratory Parameters (n = 21)Characteristic Number (%)Age, mean SD (years) 55.09 10.08Current smoker 9 (42.86%)BMI SD (kg/m2) 22.56 3.54Diabetes mellitus (DM) 2 (9.52%)Hypertension (HT) 6 (28.57%)Family history of DM, HT and/or IHD 7 (33.33%)No past and/or family history of DM, HT 11 (52.38%)Presented < 3 hours of chest pain onset 8 (38.10%)Presented >12 hours of chest pain onset 7 (33.33%)Thrombolytic therapy given 8 (38.10%)Single vessel disease 13 (61.90%)Double vessel disease 4 (19.05%)Triple vessel disease 4 (19.05%)

Table 2. Correlation of ECG Criteria with Coronary AngiographyGroups by ECG Sensitivity (%) Specificity (%) PPA (%) NPA (%)Ia 42.86 92.86 75.00 76.47Ib 0.00 90.00 0.00 94.74Ic 50.00 78.95 20.00 93.75Ib+c 100.00 77.78 42.86 100.00I 100.00 90.91 90.91 100.00IIa 71.43 92.86 83.33 86.67IIb 100.00 89.47 50.00 100.00II 100.00 91.67 90.00 100.00III 0.00 100.00 - 90.48

Groups Ib+c and IIb (100% each) followed by GroupIIa (71.43%), Group Ic (50%), Group Ia (42.86%) andleast forGroupIb (0%).Thespecificitywasmaximumfor Groups Ia and IIa (92.86% each) followed by Group Ib (90%), Group IIb (89.47%), Group Ic (78.95%) andGroupIb+c(77.78%)inthatorder.ThePPAandNPAforGroupIa,Ib,Ic,Ib+c,IIaandIIbwere75%and76.47%,0% and 94.74%, 20% and 93.75%, 42.86% and 100%,83.33% and 86.67% and 50% and 100%, respectively.

DISCuSSIon

In anterior wall myocardial infarction (AWMI), the occlusion is nearly always in the LAD coronary artery. With inferior wall myocardial infarction (IWMI), however, either the RCA or the LCx coronary artery may contain the culprit lesion.1 Rarely, acute IWMI may result from occlusion of the recurrent LAD branch,

which is the terminal portion of a wraparound LAD.

In AWMI, ST-segment elevation in leads V1, V2 and V3 indicates occlusion of the LAD coronary artery. ST-segment elevation in these three leads and in lead aVL in association with ST-segment depression of >1 mm in leads II, III and aVF indicates proximal occlusion of the LAD artery. In this case, the ST-segment vector is directed upward, toward leads V1, aVL, aVR and away from the inferior leads. ST-segment elevation in leads V1, V2 and V3 without significant inferior ST-segment depression suggests occlusion of the LAD artery after the origin of the first diagonal branch. ST-segment elevation in leads V1, V2 and V3 with elevation in the inferior leads suggests occlusion of theLADarterydistaltotheoriginofthefirstdiagonalbranch, in a vessel that wraps around to supply the inferoapical region of the left ventricle. New rightbundle-branch block (RBBB) with a Q-wave preceding the R-wave in lead V1isaspecificbutinsensitivemarkerof proximal occlusion of the LAD artery in association with anteroseptal myocardial infarction.1

In IWMI, several ECG criteria identify RCA or LCx as the artery containing the culprit lesion. Each of these criteria is based on one of two anatomic facts.2 First, the myocardial distribution of the RCA is slightly rightward in the frontal plane, and consequently the current of injuryresultingfromitsocclusionwillbereflectedmorein lead III than lead II and ST will be more in lead aVL than in lead I. Conversely, the distribution of the LCx isslightlyleftwardinthefrontalplane,andthecurrentof injury from its closure will be seen more in lead II than lead III. Similarly, the current of injury with RCA occlusion is more or less perpendicular to the axis of lead aVR, whereas the current of injury resulting from occlusion of the LCx has a mean vector that forms an obtuseanglewiththeaxisofaVR.Therefore,significant

NPA: Negative predictive accuracy; PPA: Positive predictive accuracy.


CardIology

ST-segment depression in aVR is more likely to occur withLCxocclusion.An injuryvector leftwardenoughto cause ST-segment elevation in lead I is common with LCx occlusion, but rare with RCA occlusion. Second, the RCA provides almost all of the blood supply to the right ventricle, which is rightward as well as anterior to left ventricle.When the RCA is occluded proximalto one or more of its major RV branches, ST-segment elevation is likely to be seen in lead V4R. Similarly,the ST-segment in lead V1 (V2R) may be elevated even when the more leftward precordial leads show ST-segment depression due to the posterior injury that so frequently accompanies acute IWMI. Evidence of acute RV infarction is important, not only because it identifies the RCA as harboring the culprit lesion,but especially because it predicts a greatly increased morbidity and mortality. Consequently, right precordial leads or at least lead V4R should be recorded in allpatients with acute IWMI. ST-segment depression in V1 and V2 indicates posterior injury and is typical of LCx occlusion.

Mortality and morbidity in part are determined by the location of the occlusion. For example, in patients with inferior MI who have RV infarction, the culprit artery virtually always is the RCA. Such patients, including those in whom ECG evidence of RV MI is masked, are at increased risk for death, shock and arrhythmias, including atrioventricular block.2 Thus, identifying the culpritarteryinacuteIWMIhelpsdefinethoseinwhomaggressive reperfusion strategies are likely to yield mostbenefit.Coronaryarteriographyisthebestmeansof determining the culprit artery in acute IWMI. When both the RCA and LCx are severely diseased, however, decidingwhich one is the culprit can be difficult andhaving an independent predictor of the culprit artery, such as the ECG, can be very helpful.

Engelen et al in a study of patients with AWMI showed thatfordifferentECGcriteriaweusedinourstudytolocalize LAD occlusion proximal to S1 and/orD1 (i.e., patients in group Ia and Ib in the present study), the sensitivity,specificity,PPAandNPAvariedfrom12%to44%,85to100%,67to100%and61to70%,respectively.3 Similar figures for ECG criteria to localize occlusionin LAD distal to S1 and/orD1 (i.e., patients in Group Ib and Ic in the present study) were 22-41%, 86-95%, 77-92%and46-53%,respectively.

In a study by Herz et al in patients with inferior wall AMI, the sensitivity to localize RCA occlusion varied from55%to94%.4Thespecificity,PPAandNPAvariedfrom 71% to 100%, 88% to 100% and 29% to 75%, respectively. The sensitivity, specificity, PPA andNPA

for LCx coronary artery were 88%, 100%, 100% and 97%, respectively.4 Kosuge et al studied the criteria of ratio of ST V3/ST III in patients with acute IWMI and found the sensitivity, specificity, PPA and NPAfor RCA occlusion proximal to RV branch to be 91%, 91%, 88% and 93%, respectively.5ThesimilarfigureforRCAocclusiondistaltoRVbranchwere84%,93%,91%and 88% and those for LCx coronary artery occlusion were84%,95%,73%and98%,respectively.5 Nair et al found that quantifying ST-segment depression in lead aVRdistinguishedaculpritLCx(1mm)fromaculpritRCA (


CardIology

Table 4. Diagnostic Accuracy of Different ECG Criteria in IWMI in Different Studies Studies ECG criteria IRA Sensitivity Specificity PPA NPAHerz et al4 Various criteria RCA 55-94 71-100 88-100 29-75

LCx 88 100 100 97Kosuge et al5 Ratio of ST V3/ST III RCA proximal to

RV branch (0.5, 1.2) 84 95 73 98Verouden et al8 ST III >II, STI or aVL >1 mm RCA 70 72 - -Verouden et al8 Above + ST deviation >18.5 mm RCA 90 - - -Zimetbaum et al9 ST in III>II and I and/or aVL II and any ST in I RCA 76 66 89 42Bairey et al11 ST in I RCA 79 61 89 44Bairey et al11 ST in aVL RCA 95 24 82 56

Table 3. Diagnostic Accuracy of Different ECG Criteria in AWMI (Engelen et al3) IRA ECG criteria Sensitivity Specificity PPA NPALAD proximal to S1 ST aVR* 43 95 86 70

ST II 1.0 mm* 36 100 100 68ST III 1.0 mm 60 71 60 71ST III 2.5 mm 33 97 88 67

ST aVF 1.0 mm 52 84 71 71ST aVF 2.0 mm 26 97 85 64

cRBBB* 14 100 100 62ST V5 1.0 mm* 17 98 88 62ST V1 2.5 mm* 12 100 100 61

LAD proximal to D1 ST II 1.0 mm* 34 98 93 68ST III 1.0 mm 66 75 64 76ST III 2.5 mm 32 95 81 67

ST aVF 1.0 mm 54 85 71 72ST aVF 2.0 mm 27 97 85 66

Q aVL* 44 85 67 69LAD distal to S1 Absence of ST II 67 74 78 62

Absence of ST III* 34 86 77 49Absence of ST aVF 45 90 87 54

Q V6 17 100 100 47Q V5* 24 93 82 47Q V4 55 69 71 53

LAD distal to D1 Absence of ST II 66 73 78 60Absence of ST III* 41 95 92 53Absence of ST aVF 44 90 87 53

STaVL* 22 95 87 46*Criteria used in the present study; AWMI: Anterior wall myocardial infarction; IRA: Infarct related artery; NPA: Negative predictive accuracy, PPA: Positive predictive accuracy, ST: ST-segment elevation; ST: ST-segment depression.

IRA: Infarct related artery; IWMI: Inferior wall myocardial infarction; NPA: Negative predictive accuracy; PPA: Positive predictive accuracy, ST: ST-segment elevation; ST: ST-segment depression.


CardIology

whom had severe degree of obstruction. Among them one each was in Group Ia and IIa, two each in Group Ib and IIb and four in Group Ic. One patient each from Group Ia and IIa had occlusion in LCx coronary artery, which were not diagnosed by ECG, which is a known poor tool to diagnose such occlusion. One patient in Group Ib had more distal occlusion in LAD coronary artery (i.e., Group Ic by CART). Though, the occlusion was in distal LAD, he had diseased posterior descending artery (PDA) and thus the amount of myocardium jeopardized might have been substantial by virtue of the severity of disease in other artery and hence less chance of good collateral circulation. Rest of the seven patients had more proximal lesion by CART but in the same artery as predicted by ECG. The more proximal lesions in these cases were of severe degree and all patients had single vessel disease. Thus, the possible collateral circulation that might have developed long before theAMI in such cases couldhave led to bettermyocardial salvage in spite of a proximal lesion giving rise to false ECG diagnosis of distal lesion.

ConCluSIon

The present study demonstrates that ECG is an easily and widely available inexpensive tool to localize site of occlusion in culprit vessel in acute STEMI.

limitation

The present study has two major limitations. Its sample size is small and coronary angiography was not done immediately on presentation but at a later date in otherreferralcenters.Sometimesitbecomesdifficulttoincriminate a lesion as the culprit one if angiography is done later in the course especially if there is multivessel disease or thrombolytic therapy has been given.

RefeRenCeS

1. Gorgels AP, Engelen DJ, Wellens HJ. The electro cardiograminacutemyocardialinfarction.In:HurststheHeart. 11th edition, Fuster V, Alexander RW, ORourke RA(Eds.),McGraw-Hill:NewYork2004:p.1351-60.

2. Fiol M, Cygankiewicz I, Carrillo A, Bays-Genis A, Santoyo O, Gmez A, et al. Value of electrocardiographic algorithm based on ups and downs of ST in assessment of a culprit artery in evolving inferior wall acute myocardialinfarction.AmJCardiol2004;94(6):709-14.

3. Engelen DJ, Gorgels AP, Cheriex EC, De Muinck ED, Ophuis AJ, Dassen WR, et al. Value of the electrocardiogram in localizingtheocclusionsiteintheleftanteriordescendingcoronary artery in acute anterior myocardial infarction. JAmCollCardiol1999;34(2):389-95.

4. HerzI,AssaliAR,AdlerY,SolodkyA,SclarovskyS.Newelectrocardiographic criteria for predicting either the right orleftcircumflexarteryastheculpritcoronaryarteryininferior wall acute myocardial infarction. Am J Cardiol 1997;80(10):1343-5.

5. KosugeM,KimuraK,IshikawaT,HongoY,MochidaY, Sugiyama M, et al. New electrocardiographic criteria for predicting the site of coronary artery occlusion in inferior wall acute myocardial infarction. Am J Cardiol 1998;82(11):1318-22.

6. Nair R, Glancy DL. ECG discrimination between right and leftcircumflexcoronaryarterialocclusioninpatientswithacuteinferiormyocardialinfarction:valueofoldcriteriaanduseofleadaVR.Chest2002;122(1):134-9.

7. Wellens HJ. The ECG in localizing the culprit lesion in acuteinferiormyocardialinfarction:apleaforleadV4R?Europace2009;11(11):1421-2.

8. Verouden NJ, Barwari K, Koch KT, Henriques JP, Baan J, van der Schaaf RJ, et al. Distinguishing the right coronary artery from the left circumflex coronary artery as theinfarct-related artery in patients undergoing primary percutaneous coronary intervention for acute inferior myocardialinfarction.Europace2009;11(11):1517-21.

9. Zimetbaum PJ, Josephson ME. Use of the electro-cardiogram in acute myocardial infarction. N Engl J Med 2003;348(10):933-40.

10. ChiaBL,YipJW,TanHC,LimYT.UsefulnessofSTelevationII/III ratioandSTdeviation in lead I for identifying theculprit artery in inferior wall acute myocardial infarction. AmJCardiol2000;86(3):341-3.

11. Bairey CN, Shah PK, Lew AS, Hulse S. Electrocardiographic differentiation of occlusion of the left circumflexversusthe right coronary artery as a cause of inferior acute myocardialinfarction.AmJCardiol1987;60(7):456-9.

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ecg and coronary angiogram correlation

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