1. Localization of culprit artery in STEMI
Dr Bijilesh u
Senior Resident,
Dept. of Cardiology,
Medical College, Calicut

2. Careful analysis of the Surface ECG is highly useful in localizing the culprit vessel and immediate prognostication
Helps in deciding the need for an aggressive reperfusion strategy

3. Coronary circulation Left Main or left coronary artery (LCA)
Left anterior descending (LAD)
diagonal branches (D1, D2)
septal branches
Circumflex (Cx)
Marginal branches (M1,M2)
Right coronary artery
Conus , sinoatrial branch
RV branch
Acute marginal branch (AM)
AV node branch
Posterior descending artery (PDA)

4. LAD large MIs
Supplies the anterior, lateral, anterior two-thirds of septum, and frequently the inferoapical segments of the left ventricle, proximal part of bundle branches
RCA
Perfuses sinus node (55%), AV node, posteromedial papillary muscle, inferior part of LV, RV, and variably also the posterior and lateral segments

5. Circumflex branch
Posterior wall and variably inferior and lateral segments
Posterior wall involvement  usually underestimated and under treated.

6. Bundle of His – mainly RCA RBB – LAD
SA node – RCA in 55%
AV node – RCA in 90%
Bundle of His – mainly RCA
RBB – LAD
LBB – L Ant branch – LAD L Post branch – LAD & Postr Desend A
Obstruction 0f bld sply 2 cond system can esult in cond syts abnormalities

7. Dominance
Supplies circulation to the inferior wall & inferior portion of the interventricular septum
Passes crux and interventricular septum, giving rise to posterolateral branches & PDA
Dominant artery also gives rise to the AV nodal branch
Cor circ can b r or l dominant sy

8. RIGHT DOMINANT
Along the inferior (diaphragmatic) aspect of the heart, the atrioventricular, interventricular, and interatrial grooves form a cross-shaped intersection called the crux cordis (crux of the heart).

9. LEFT DOMINANT

10. Dominance RCA - 70% LCX - 10% Co - dominant – 20%
Identifies patients at risk for extensive myocardial damage with complications
It is very
important to recognize which vessel is dominant because this

11. ST VECTOR
Direction and displacement of the ST segment - sum of direction and magnitude of all ST vectors
Resulting main vector point in the direction of the most pronounced ischemia - ST elevation in that area
Opposite area record (reciprocal) ST depression
Lead perpendicular to dominant - iso-electrical ST segment

12. AWMI

13. ECG in AWMI
STE in V2, V3, V4
Behaviour of ST in other leads depends on the presence of ischemia in three vectorally opposite areas
Basoseptal area (1st septal branch)
Basolateral area (1st diagonal branch)
Inferoapical area ( when LAD wraps around apex)

14. Types of LAD occlusion
Proximal to 1st septal and 1st diagonal branch (40%)
Distal to S and D (40%)
Proximal to D1 but distal to S1 (10%)
Proximal to S1 but distal to D1 (10%)

15. Proximal LAD occlusion (Dominance of Basal area)

16. Direction of ST Vector and ECG Changes in Proximal LAD Occlusion

17. Proximal LAD occlusion (Dominance of Basal area)
ECG…
RBBB
STE aVR and STE in V1 > 2.5 mm
ST depression in inferior leads and in V5

19. Distal LAD occlusion (dominance of inferoapical area)
St vector points inf due to ischemic dom of inferoapical area. Iferiorly directed vector leads to st d in avr n ste in inf leads

20. Distal LAD occlusion (dominance of inferoapical area)
ECG…
Absence of ST depression in inferior leads
STE in inferior leads in addition to V3-V6

22. 1st Diagonal not involved (Dominance of septal area)--Proximal to S1
Direction of st vec in medial direction result ste avr 3 std in avl

23. 1st Diagonal not involved (Dominance of septal area)
ECG…
STE in aVr and > 2.5 mm STE in V1
ST depression in V5
STE in V3R
ST depression in aVL (Highly specific)

25. First septal branch not included (dominance of Lateral area) – Proximal to D1
Dominance of isch inlat area result in st vector pointing in that direction.. Leads to ST negativity in 3 and avr .2 isoelectric. 1 n avl ste

26. First septal branch not included (dominance of Lateral area)
ECG…
ST depression in Lead III > Lead II
ST elevation lead AVL & lead 1

28. ECG criteria to identify site of occlusion in the LAD
Engelen et al
J Am Coll Cardiol. 1999;34:
Right bundle branch block remains, as described in chapter 3, a very
specific marker of an occlusion before the first septal branch. ST elevation in
has to be more than 2mm to be sufficiently specific for that location. ST
elevation in AVR is apart from being specific the most sensitive marker for
proximal LAD occlusion. ST depression in is not a very frequent, but
specific marker.
Lead AVL is the most useful lead to identify an occlusion site proximal
(starting with a Q wave) or distal (showing a negative ST segment) to the first
diagonal branch

29. Inferoposterior wall MI

30. Both arteries supply inf part of lv
Both arteries supply inf part of lv.. Rca more medially including the inf septum cx postero basal and lateral area. So st vec inf n r in rca and inf n left in cx

31. Occlusion of the RCA ST-segment elevation in III > II
ST-segment depression in I and aVL - aVL > I
Herz I, Assali AR et al Am J Cardiol 1997;80:
ST depression in the precordial leads is smaller than ST elevation in inferior leads
When occlusion is proximal to RV branches ST elevation in V1 > V3 V4
LAD occlusion ST elevation in V3V4 > V1

33. Dominance of RCA
When RCA is dominant, ST-segment elevation is seen in V5 and V6
ST-segment elevation ≥ 2 mm - RCA very dominant
Involvement of posterior wall
PR prolongation.. AV nodal artery arises from dominant artery

34. Occlusion of the LCX ST- elevation in II ≥ III
ST elevation in I and aVL.
ST-segment elevation in II, III, and aVF is usually smaller than the ST depression in right precordial leads
When LCX is quite dominant - ST depression in aVL, but very rarely in I

36. STE in these leads implies a larger area at risk
Right coronary
Circumflex coronary
Inferoseptal ischemia
Inferoposterolateral isch.
Vector directed to III
Directed to II
STE III > II
STE II > III
ST depression in aVL>I
ST depression in I>aVL
RV can be involved
True PWMI can occur
V5 and V6 are of little value in differentiating between RCA or Cx occlusion.
STE in these leads implies a larger area at risk

37. OM vs D1 OCCLUSION 0M D1 ST elevation I, aVL, and V5−6
Slight ST depression in V1-3
ST elevation I, aVL, and V5−6
ST-elevation in precordial leads
ST-depression inferior leads.

38. RV infarction

39. RV infarction STE >1mm V3R and V4R STE V1 > V2
High degree AV block

40. Value of ST – T changes in V4R in acute infero posterior MI
(RVMI)
Braat SH, Gorgels APM, Bar FWHM, Wellens HJJ
Am J Cardiol 1998;62:

42. Isolated RVMI Minor changes in inferior leads,
STE prominent in leads V1 and V2 , V3R and V4R
Small or collaterally filled RCA
Occlusion of an RV branch only

43. ST depression in anterior leads in IWMI
Implies posterior wall involvement
May extend from V1 to V6 and indicate larger MI
Maximal ST depression in V4 – V6 is seen more in three vessel disease and lower LVEF
Birnbaum Y,
J Am Coll Cardiol 1996;28:
Can occur both in RCA and Cx artery invt
Absence indicates RCA

44. ST depression in anterior leads
Isolated ST depression – Cx occlusion with a true PWMI or nonocclusive myocardial ischemia
Max ST depression in V2 and V3 is predictive of Cx
V7 –V9 shows ST elevation

45. True PWMI ST depression in V1, R/S >1, and upright T wave V1 V9
diagnosed by finding reciprocal ST segment
depression in the precordial leads. When present in RCA occlusion, it indicates
dominance of this vesselIn case of CX occlusion posterior wall involvement is almost obligatory V1 V9

46. AV conduction disturbances
AV nodal delay and block occurs with proximal RCA invt, frequently with RVMI
Higher in-hospital morbidity & mortality

47. Sub AV conduction disturbances
RBBB with or without hemiblock during acute AWMI indicates proximal LAD
BBB or CHB indicates poor prognosis
LAHB in acute IWMI indicates additional LAD disease

48. LEFT MAIN STEM OCCLUSION OR TRIPLE VESSEL DISEASE
Acute LMCA occlusion rare but causes serious hemodynamic deterioration
More commonly, subtotal occlusion occurs with collaterals filling from RCA  presents as Unstable angina
ECG of subtotal occlusion similar to triple vessel disease

49. LEFT MAIN STEM OCCLUSION OR TRIPLE VESSEL DISEASE
Marked downsloping ST depression in I, II, and V4 – V6 and STE in aVR
aVR STE occurred more in LMCA than in LAD
V1 STE was less in LMCA than LAD
High mortality rate in those with higher STE in Avr
Yamaji H et al
J Am Coll Cardiol 2001;38:

51. Atrial infarction Signs of atrial MI are seen in PTa segment
PTa segment elevation occurs in I, II, III, V5 or V6 or a depression in precordial leads
Occurs in 10 % of inferoposterior MI
Isolated occurrence is rare
Proximal RCA or Cx

54. RCA vs LCX

55. Limitations
Assessment of the site of occlusion of coronary vessel by ECG is most reliable in case of 1st MI
Impaired
Multivessel disease
Collateral circulation
When ventricular activation is prolonged as in
LVH
Preexistent LBBB
Preexcitation
Paced rhythm

56. REFERENCE Bayes de Luna, Antman - The 12 lead ECG in STEMI
Hein J J Wellens, Anton P M Gorgels, Pieter A Doevendans: The ECG in Acute Myocardial Infarction and Unstable angina – diagnosis and risk stratification
Y .Birnbaum Bj Drew – Ecg in STEMI - correlation with coronary anatomy and prognosis
YAMAJI H - Prediction of acute left main coronary artery obstruction by 12-lead electrocardiography. ST segment elevation in lead aVR with less ST segment elevation in lead V(1)