University Heart Journal

Vol. 10, No. 2, July 2014

REVIEW ARTICLES
Prediction of Location of Infarct-related Artery in acute
Myocardial Infarction from Surface Electrocardiogram, its
Clinical Importance and Therapeutic Strategy: A Review
MOSTASHIRUL HAQUE1, MD. SHAFIULALAM2, SABBIR JASHIM AHMED2, SUFIA KHATUN2, NUSRAT JAHAN URMI2,
ARIFUL ISLAM JOARDER3, MD. RASUL AMIN3, LOHANI M MD. TAJUL ISLAM3, MD. NAZMUL HASAN3
1Department of Cardiology, Anwer Khan Modern Medical College Hospital, 2Department of Medicine, BIRDEM General
Hospital, 3Department of Cardiology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka
Address of correspondence: Dr. Mostashirul Haque, Assistant Professor, Department of Cardiology, Anwer Khan Modern
Medical College Hospital, Dhanmondi, Dhaka, Email: mustashir.haque@yahoo.com

Introduction: elevation of <1 mm in inferior leads,ST-segment elevation

Acute myocardial infarction is a common disease with other than inferior leads, left ventricular hypertrophy(LVH),
serious consequences in mortality, morbidity, and cost to left bundle branch block(LBBB), presence of conditions
the society.1 Acute myocardial infarction (AMI) has always causing ECG changes (electrolytes disturbances,
been a potential health problem due to the life-threatening myocarditis, pericarditis etc).3
complications. Coronary atherosclerosis plays a pivotal Erdem Alim et al has shown the patients with the culprit
part as the underlying substrate in many patients.2 MI lesion in the proximal portion were found to have a mean
results from prolonged myocardial ischemia precipitated ST segment elevation >12 mm but in the mid RCA and
in most cases by an occlusive coronary thrombus at the distal RCA portion were found 6 mm and 5 mm,
site of a pre-existing atherosclerotic plaque.1 Although respectively.3
coronary angiogram (CAG) is the gold standard to localize
the site of coronary obstruction, ECG is an important tool A ST segment elevation value of >9 mm was found to
in determining therapeutic strategy in acute coronary have sensitivity and specificity of 91.3% and 94.6%,
syndrome (ACS) in the setting of AMI.3 respectively in the prediction of infarct related proximal
RCA lesions.3
Discussion:
The presence of more severe ST segment elevation in the
The diagnosis of infarct related artery (IRA) is very
L3 compared to that in L2 was found to have a sensitivity
important with regard to the prediction of potential
of 99%, specificity 100% and positive predictive value of
complications and subsequent therapeutic strategy in
99% in the RCA occlusion in AIMI.4
acute inferior myocardial infarction (AIMI). The IRA is
right coronary artery (RCA) in 80% of cases, while it is left Anterior MI carries worst prognosis of all infarct locations,
circumflex (LCX) in the rest.2 AIMI is sometimes mostly due to large infarct size. A study comparing
complicated by hypotension or bradycardia, generally outcomes from anterior and inferior infarctions
occurs in case of proximal RCA occlusion. So it is clinically (STEMI+NSTSEMI) founded that on average, patients
important to determine proximal RCA occlusion to predict with anterior MI had higher incidences of in-hospital
their potential complications and outline the therapeutic mortality (11.9 vs 2.8%), total mortality (27 vs 11%), heart
strategy in AIMI.3 failure (41 vs 15%) and significant ventricular ectopic
activity (70 vs 59%) and a lower ejection fraction on
Erdem Alim et al have studied sixty patients admitted to
admission (38 vs 55%) compared to patients with inferior
their center with diagnosis of AIMI.
MI.5,6
Inclusion Criteria: acute inferior myocardial infarction is
A number of studies have focused on the relationship
defined as presence of persistent ischemic chest pain (>30
between ECG changes and infarct related artery (IRA).
min), ST-segment elevation at least 1 mm in at least two of
the inferior leads (L2, L3, aVF) and presence of at least two Birnbaum et al propounded ST segment depression in
fold increase of cardiac biomarker (CK-MB) level compared aVL lead- one of the sensitive and earliest parameter of
to normal baseline value. Exclusion criteria: ST-segment AIMI.7
University Heart Journal Vol. 10, No. 2, July 2014

Patients with an abnormal R wave in V1 (0.04 second in Deep symmetrical precordial T wave inversions > 2mm or
duration and R/S ratio>1 in the absence of pre-excitation biphasic T waves in V2-V3 indicating proximal LAD
or right ventricular hypertrophy(RVH) with inferior or lateral occlusion: a warning sign of imminent anterior infarction
Q waves have an increased incidence of isolated occlusion (Wellens syndrome).23 A new ECG sign of proximal LAD
of a dominant LCX without collateral circulation.8 occlusions: Upsloping ST depression with symmetrically
peaked T waves in the precordial leads; a “STEMI
Berry et al demonstrated that ST segment depression in
equivalent” indicating acute LAD occlusion (de Winter”s
both aVL and L1 leads was a marker of RCA occlusion in
T wave).16
AIMI.9
An isolated true posterior MI is unusual, less common (3-
Right-sided ST-segment elevation is indicative of acute
11% of infarcts). Posterior MI accompanies 15-20% of
right ventricular injury and usually indicates occlusion of
STEMIs usually occuring in the context of an inferior or
the proximal RCA. Acute RVI projects an injury current in
lateral wall infarction. In such situation, the ECG changes
leads V1-V3, thereby simulating anterior infarction.10
of posterior wall infarction (Tall, broad R waves ( >30ms)
Leads aVR may provide important clues to artery occlusion
in MI.11 with ST-depression in V1-V2, upright T wave, dominant R
wave(R/S ratio >1 in V2) are added.17
Zehender et al found an incidence of 27% of RVI associate
with inferior MI based on electrographic criteria.22 In AIMI Clinical Importance:
the more severe ST-segment elevation in L2 compared to Therefore, it is clinically important to determine the
that in L3 was found to have positive predictive value of proximity of culprit lesion along RCA to predict the patients
98% in the LCX occlusion.11 Inferior MI with ST depression potentially at risk for AIMI related complications including
in V1-V3 more associated with LCX occlusion (71%) than brady-arrhythmia and severe hypotension. 3 Right
RCA occlusion.12 ventricular infarction is associated with increased risk of
Ratio of ST-segment depression in V3 to ST-segment death, ventricular tachycardia or fibrillation and
elevation in L3 < 0.5 predicts proximal RCA occlusion, 0.5- atrioventricular blocks. 18 The frequency of VF and
1.2 predicts distal RCA occlusion and > 1.2 predicts LCX iatrogenic coronary dissection is higher when RCA is
occlusion.12 injected in the presence of a damped pressure tracing
indicating ostial stenosis. Posterior extension of inferior
Inferior MI with ST-segment elevation in lateral leads (I,
or lateral infarct implies a much larger area of myocardial
aVL, V5 & V6) sensitive and specific marker for LCX
damage, with increased risk of LV dysfunction and death.17
occlusion.8
It is pertinent to define the site of occlusion of LAD in the
Acute anteroseptal MI (with STE maximal in lead V1-V4),
setting of AMI because proximal LAD occlusion needs
the following signs suggests proximal LAD occlusion:
more aggressive approach to revascularization to prevent
presence of ST-segment depression >1mm in inferior leads,
extensive myocardial damage, development of sub-AV
ST-segment elevation in lateral leads (aVL), ST-segment
nodal conduction disturbances and occurrence of life
elevation in lead aVR and right bundle branch block
threatening arrhythmias.10 Massive ST elevation with
(RBBB).13 Left main or severe multi-vessel disease should
“tombstone” morphology is present throughout the
be considered when leads aVR and V1 show ST-segment
precordial(V1-V6) and high lateral leads(1,aVL);this pattern
elevation with diffuse prominent ST depression in other
is seen in proximal LAD occlusion and indicates a large
leads.11, 14
territory infarction with poor LV ejection fraction and high
STE in aVR of any magnitude is 43% sensitive and 95% likelihood of cardiogenic shock and death.5,13 In LMCA
specific for proximal LAD occlusion.13 disease, most patients are symptomatic and high risk of
RBBB in anterior MI is an independent marker of poor CV events, since occlusion of this vessel compromises
prognosis; this is due to the extensive myocardial damage flow to at least 75% of LV, unless it is protected by collateral
involved rather the conduction disorder itself.13 flow or a patent bypass graft to either the LAD or LCX.6,11

Inferior lead ST-segment elevation accompany acute Therapeutic strategy:

anterior MI suggesting either primary occlusion of a LAD In patients presenting with inferior STEMI, who received
that extends onto the inferior wall of LV (the type 111 or fibrinolytic therapy, a routine invasive strategy with early
wrap-around LAD) or multi vessel disease (MVD) with CAG and intended revascularization, achieve a clinical
jeopardized collaterals.15 outcome similar to an ischemia-guided strategy in which

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Prediction of Location of Infarct-related Artery in acute Myocardial Infarction Mostashirul Haque et al.

catheterization was based on the presence of myocardial indentifying the location of the occluded coronary artery in
inferior MI. Am J Cardiol 1998;81:918-19.
ischemia and viability as demonstrated by stress-
5. Eskola MJ, NIkus KC, Homvang L et al.Value of 12 lead ECG
myocardial perfusion imaging (MPI).19 Pre hospital to define the level of obstruction in acute anterior MI:
fibrinolytics with timely (6-24h) CAG with a view to correlation to CAG and clinical outcome in DANAMI-2 trail.
revascularization (Pharmacoinvasive strategy) results in Int J cardiol 2009;131:378-83.
effective reperfusion in patients with early STEMI who 6. Kosuge M, Kimura K, Ishikawa T et al. Predictors of LM or
three vessels disease in patients who have ACS with NSTEMI.
could not undergo primary PCI (pPCI) within 1 hour after
Am j Cardiol 2005; 95:1366-69.
first medical contact.20 In the strategic reperfusion early
7. Birnbaum Y, Sclarovsky S, Solodky A, et al. Prediction of the
after MI (STREAM) trail, a pharmacoinvasive (PI) strategy level of LAD obstruction during AMI (anterior wall) by
was compared to the pPCI in STEMI patient presenting admission electrogram. Am J Cardiol 1993 ; 72 : 823-26.
within 3 hours after symptoms onset but unable to undergo 8. Herz I, Assali AR, Adier Y et al. New ECG criteria for predicting
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Am J cardiol 1997; 8:1343.
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9. Berry C, Zalewski A, Kovach R et al. Surface electrogram in
Isolated posterior infarction is an indication for emergent detecting of transmural MI during coronary artery occlusion.
coronary reperfusion.17 Am J cardiol 1989; 21-6.
10. Zimetbaum PJ, Josephson ME: Use of the electrocardiogram
The appropriateness of coronary artery bypass (CABG) in acute myocardial infarction. N Eng J Med 2003; 348; 933.
surgery versus percutaneous coronary intervention (PCI) 11. Nikus KC, Sclarovsky S. ST-segment elevation in lead AVR of
is predicted on clinical, anatomic and functional grounds. a sign of Left main disease – Perpetuating an error. Am J
In the coronary artery surgery study (CASS), isolated left cardiol 2004; 94:542.
main coronary artery (LMCA) disease, left main equivalent 12. Kosuge M, Kimura K, Ishikawa T et al. New electrographic
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grade lesion of the proximal LAD have a significant better MI. J Am Coll Cardiol 1999 ; 385-95.
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