A detailed list of few important STEMI EQUIVALENTS that is very relevant on day to day life.

1. STEMI-
EQUIVALENTS..an
opportunity to save
the myocardium
BY DR SAMYAJYOTI DAS
JUNIOR RESIDENT
DEPARTMENT OF CARDIOLOGY,CRH

2. BACKGROUND
STEMI typically defined by
◦ ≥1 mm (0.1 mV) ST segment elevation in limb leads
◦ ≥ 2 mm ST segment elevation in precordial leads
◦ Findings present in at least 2 anatomically contiguous
leads
Several variations from the classic STEMI ECG changes are
similarly concerning and considered 'STEMI equivalents’

3. STEMI EQUIVALENTS-
1.Posterior MI
Seen in RCA (90%), LCA (10%)
12-Lead ECG findings
◦ ST-segment depression
◦ Prominent and broad R wave (>30ms)
◦ Relative tall R waves in precordial leads (may find R = S amplitude in
V1)
◦ R/S wave ratio >1.0 in lead V2
◦ Prominent, upright T wave
◦ Combination of horizontal ST-segment depression with upright T wave

4. ST-segment depression
Prominent and broad R wave (>30ms)
Relative tall R waves in precordial leads (may find R = S amplitude in V1)
R/S wave ratio >1.0 in lead V2
Prominent, upright T wave

5. • Posterior ECG or 15-lead ECG may be helpful
V7: Left posterior axillary line along the 5th ICS
V8: Tip of the left scapula line along the 5th ICS
V9: Left paraspinal area line along the 5th ICS
• Posterior ECG findings
≥0.5 mm ST-segment elevation

6. Marked ST elevation in V7-9 with Q-wave formation confirms involvement of the posterior wall

9. • Image of grade 6
thrombus in the
RCA
• Arrowed in black is
the thrombus area
where you can
notice an abrupt
blunt cut-off
appearance beyond
which no dye is
penetrating the
artery .

10. 2.LMCA Occlusion
• Seen with left main artery lesion
• Also reported in proximal LAD lesions and
severe multivessel coronary artery disease
• 12-Lead ECG findings:-
ST elevation in aVR ≥ 1mm
ST elevation in aVR ≥ V1
ST depression typically seen in lateral

11. ST elevation in aVR ≥ 1mm
ST elevation in aVR ≥ V1
ST depression typically seen in lateral

12. Coronary angiography: distal sub occlusion 99% of the left main artery (LMCA) including the
origin of left anterior descendent (LAD) and circumflex arteries(Cx)

13. 3.De Winter’s T Waves:-
• Suggests proximal LAD lesion
• 12-Lead ECG findings
1. Precordial ST-segment depression at the J-
point
2. Tall, peaked, symmetric T waves in the
precordial leads
3. Lead aVR shows slight ST-segment elevation
in most cases

14. 1. Precordial ST-segment depression at the J-point
2. Tall, peaked, symmetric T waves in the precordial leads
3. Lead aVR shows slight ST-segment elevation in most cases

15. Coronary angiography: left descendant artery
in second segment occlusion (see arrow)
Coronary angiography: After Instent post dilation

16. 5.Wellens’ Syndrome:-
• ECG findings in absence of chest pain, but with recent cardiac chest pain
symptoms
• Represents critical stenosis of the LAD
• Requires PCI in the next 24-48hr (may evolve more rapidly - observe with
serial ECGs)
• 12-Lead ECG findings
1. Deeply-inverted or biphasic T waves in V2-3
2. Isoelectric or minimally-elevated ST segment (<1 mm)
3. Absent precordial Q waves with preserved R waves
• Two T wave characteristics:
Type A: Biphasic pattern - 25% - Biphasic T-waves
Type B: Inversion pattern - 75% - Deeply inverted and symmetric T-waves

19. Coronary angiogram showing critical mid left anterior
descending artery stenosis Critical LAD stenosis treated with drug eluting stent

20. 4.Sgarbossa's Criteria:
• Used to identify STEMI in the setting of LBBB or pacemaker
• Original Criteria
1. ≥3 points = 98% probability of STEMI
2. ST elevation ≥1 mm in a lead with upward (concordant)
QRS complex - 5 points
3. ST depression ≥1 mm in lead V1, V2, or V3 - 3 points
4. ST elevation ≥5 mm in a lead with downward (discordant)
QRS complex - 2 points

21. Smith's modification
• Changes the 3rd rule of original Sgarbossa's
Criteria to be ST depression OR elevation
discordant with the QRS complex and with a
magnitude of at least 25% of the QRS increases
Sn from 52% to 91% at the expense of reducing
Sp from 98% to 90%[

23. 6.New LBBB:
• New LBBB alone is no longer a reason to activate the cath
lab
• However, careful workup for ACS should be taken for
symptomatic patients with LBBB
• 12-Lead ECG findings
1. QRS > 0.12 in limb leads
2. Leads-
• Large and wide R waves — leads I, aVL, V5, and V6
• Small R wave followed by deep S wave —leads II,
III, aVF, V1–V3

24. 1. QRS > 0.12 in limb leads
2. Leads-
• Large and wide R waves — leads I, aVL, V5, and V6
• Small R wave followed by deep S wave —leads II, III, aVF, V1–V3

25. • SHARK FIN PATTERN:
• Shark Fin pattern is an uncommon but high-risk electrocardiographic
(ECG) pattern formed by fusion of QRS, ST-segment, and T waves
• Also known as 'Lambda-wave', 'giant R waves', or 'triangular QRS-ST-
T waveform’
• Most commonly involves occlusion of the left main coronary artery
and is associated with a high risk of death due to cardiac arrest and
cardiogenic shock .
• 12-Lead ECG shows :
1. blurring of the QRS complex due to its fusion with the ST-segment and the T-
wave showing a triangular lambda pattern where a positive deflection in the
leads

26. ECG showing blurring of the QRS complex due to its fusion with the ST-segment and the T-wave showing
a triangular lambda pattern(marked with arrow) where a positive deflection in the leads

27. TAKE HOME MESSAGE:
• It is important to remember that an ECG is not 100% sensitive for
coronary occlusion and that the absence of STE does not rule out an
MI.
• These STEMI equivalents can occur in patients with active,
intermittent, or no chest pain at all. Observation of these patterns
may come from a routine evaluation where the 12-lead was obtained
for some other presenting symptom
• Symptoms such as unexplained dyspnea, weakness, nausea, or
indigestion can be enough for us to evaluate things a little more in
depth and obtain an ECG tracing. Diabetics, women, and the elderly
can also present with vague symptoms or other forms of atypical
pain that would warrant obtaining one.

28. THANK YOU