RCA (90%), LCA (10%)
12-Lead ECG findings
ST-segment depression (horizontal >> downsloping/upsloping)
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
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
ST-segment depression (horizontal >> downsloping/upsloping)
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
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
≥0.5 mm ST-segment elevation

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

Suggests proximal LAD lesion
12-Lead ECG findings
Precordial ST-segment depression at the J-point
Tall, peaked, symmetric T waves in the precordial leads
Lead aVR shows slight ST-segment elevation in most cases
Precordial ST-segment depression at the J-point
Tall, peaked, symmetric T waves in the precordial leads
Lead aVR shows slight ST-segment elevation in most cases

Used to identify<unk>  in the setting of LBBB or pacemaker
Original Criteria
≥3 points = 98% probability of<unk> 
ST elevation ≥1 mm in a lead with upward (concordant) QRS complex - 5 points
ST depression ≥1 mm in lead V1, V2, or V3 - 3 points
ST elevation ≥5 mm in a lead with downward (discordant) QRS complex - 2 points
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%[
≥3 points = 98% probability of<unk> 
ST elevation ≥1 mm in a lead with upward (concordant) QRS complex - 5 points
ST depression ≥1 mm in lead V1, V2, or V3 - 3 points
ST elevation ≥5 mm in a lead with downward (discordant) QRS complex - 2 points
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%[

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
Deeply-inverted or biphasic T waves in V2-3
Isoelectric or minimally-elevated ST segment (<1 mm)
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
Deeply-inverted or biphasic T waves in V2-3
Isoelectric or minimally-elevated ST segment (<1 mm)
Absent precordial Q waves with preserved R waves
Type A: Biphasic pattern - 25% - Biphasic T-waves
Type B: Inversion pattern - 75% - Deeply inverted and symmetric T-waves
STEMI equivalents
STEMI mimics
Stable angina
Vincent's angina
Unstable angina
AVR ST elevation
T wave changes
Unstable Angina - NSTEMI Guidelines