ST segment deviation score
= sum of score on 12 lead. If > 12 mm then substantial ischemia that may
benefit from reperfusion

ST segment deviation vector:
InferoposteriorCx or RCA
STD in I
Prox RCA (prox to the RV branch) =
with RV involvement
STE > 1 mm with + T in V4R
Dist RCA
Isoelectric ST with + T in V4R
ST isoelectric or STE in I
ST isoelectric or STD with - T in V4R
Extension to Posterior: STD in precordials
STD and - T in V4R.
R>S in V1
Extension to Lateral: STE in I, aVL, V5 and V6
Click to Enlarge
-Perfuses Inferior and Posteromedial
-Prox RCA: risk of AVN block
-Perfuses posterolateral part.
-Notch at the end of the QRS in II, III, aVF indicating delayed
activation pf the basolateral area. A finding typical for Cx
Occlusion of a Dominant Cx: ST elevation II=III, I isoelectric. Subtle STE in I, aVL, V5, V6 with STD V1-V4
prox RCA => STE > 1mm with + T
  dist RCA  => ST isoelectric with + T
  Cx            => ST iso or STD with - T

When V4R is not recorded, it becomes difficult to differentiate between RCA and Cx especially when STE
in II = III and lead I is isoelectric

Fiol method when V4R is not recorded:

                                                  STD (V1+V2+V3)
                                                  ----------------------   > 1 then Cx
                                                    STE (II+III+aVF)
STD in I
STE > 1 mm and + T in V4R

Isolated RV ischemia:
STE in II, III, aVF - V1_>V6 and V4R (not to be confused with anterior STEMI)
Back to EKG main

Prox LAD - before S1 and D1
The ischemic area is in the basal part of the LV and the vector points to the base of the heart towards
leads aVR and aVL and away from the apex (away from leads II, III, aVF).
S1 perfuses the subnodal AV conduction system => conduction disturbance may occur in the His bundle
and in the RBB +/- LBB.
.STE in aVR and aVL
    .STD in II, III, and aVF
    .STE in V1 (>2 mm) and V2-V4
    .STi or STD in V5-V6
    .Acquired intra-Hissal or RBBB

Prox LAD between S1 and D1
Ischemia high in the anterolateral area of the LV and the vector pointing towards aVL and away from III
.STE in I, aVL
    .STD in III (STi II)
    .STE V2-V6 but not in V1

Prox LAD between D1 and S1
Occasionally a Diagonal D1 takes off before S1. Vector points towards aVR and II away from aVL
.STD in aVL
    .STE III>II, aVF
    .STE in V1-V4

Distal LAD
Vector points towards the apex
     .STE inferior II>III
     .STE V3-V6

Vector pointing towards aVR =>
.STE aVR, V1                                                                STE aVR > STE V1
    .STD II, aVF (basal ischemia)                                        
.STD V4-V6 (posterior ischemia)                                   STD V6>STE V1
.Often RBBB

The extent of posterior wall ischemia is known by the number of precordial leads showing STD
and the depth of depression.

Sclarovsky and Birnbaum Grades of ischemia
     Grade 1 -
peaked symmetrical T waves without ST elevation
Grade 2 - ST elevation without distortion of the terminal QRS
Grade 3 - Distortion of the terminal portion of the QRS, STE, and a junction point / R ratio > 0.5

Wiviott Risk Index
                                     Risk Index = HR x (Age/10) X 2
Inhospital Death in patients with STEMI:         
RI<30 => <5%
RI 60 => 5-30%
RI>60=> > 30%

Q waves: do not necessarily indicate necrosis. Transient Q waves caused by conduction delay in the
zone under the electrode (especially qR complexes).