TABLE 1.

Electrocardiogram Findings Suggestive of Ischemia

FINDING	CRITERIA
STEMI equivalents
Posterior STEMI	Criteria: Horizontal ST-segment depression in V1-V3 Dominant R-wave (R/S ratio >1) in V2 Upright T waves in anterior leads Prominent and broad R-wave (>30 ms) Confirmed by: ST-segment elevation of ≤0.5 mm in at least 1 of leads V7-V9*
Left bundle branch block or ventricular paced rhythm with Sgarbossa Criteria	A total score ≥3 points is required: Concordant ST-segment elevation ≥1 mm in leads with a positive QRS complex (5 points) Concordant ST-segment depression ≥1 mm in leads V1-V3 (3 points) Discordant ST-segment elevation ≥5 mm in leads with a negative QRS complex (2 points) If there is discordant ST-segment elevation ≥5 mm, consider ST/S ratio <−0.25
Left bundle branch block or ventricular paced rhythm with Smith-modified Sgarbossa Criteria	Positive if any of the following are present: Concordant ST-segment elevation of 1 mm in leads with a positive QRS complex Concordant ST-segment depression of 1 mm in V1-V3 ST-segment elevation at the J-point, relative to the QRS onset, is at least 1 mm and has an amplitude of at least 25% of the preceding S-wave
De Winter Sign	Tall, prominent, symmetrical T waves arising from upsloping ST-segment depression >1 mm at the J-point in the precordial leads 0.5–1 mm ST-segment elevation may be seen in lead aVR
Hyperacute T waves	Broad, asymmetric, peaked T waves may be seen early in STEMI Serial ECGs over very short intervals are useful to assess for progression to STEMI
ECG findings consistent with acute/subacute myocardial ischemia
aVR ST-segment elevation	Most often caused by diffuse subendocardial ischemia and usually occurs in the setting of significant left main coronary artery or multivessel coronary artery disease ST-segment elevation in aVR ≤1 mm Multilead ST-segment depression in leads I, II, Val, and/or V4-V6 Absence of contiguous ST-segment elevation in other leads
ST-segment depression	Horizontal or downsloping ST-segment depression ≥0.5 mm at the J-point in 2 or more contiguous leads is suggestive of myocardial ischemia
Wellen’s syndrome	Clinical syndrome characterized by: Biphasic or deeply inverted and symmetric T waves in leads V2 and V3 (may extend to V6) Recent angina Absence of Q waves
Inverted T waves	May be seen in ischemia (subacute) or infarction (may be fixed and associated with Q waves) in continuous leads

^*V₇ placed at left posterior axillary line in same plane as V₆; V₈ placed at the tip of the left scapula; V₉ placed in the left paraspinal region in the same plane as V₆. aVR = augmented vector right; ECG = electrocardiogram; STEMI = ST-elevation myocardial infarction.