ACLS review: Acute Coronary Syndromes Part 4

ECG classification: ST Depression

·         ST depression or T-wave inversion

·         Ischemic ST-segment depression >0.5 mm (0.05 mV) or dynamic T-wave inversion with pain or discomfort is classified as UA/NSTEMI.

·         Nonpersistent or transient ST-segment elevation ≥ 0.5 mm for 20 minutes is also included in this category

Note:  Threshold values for ST-segment depression consistent with ischemia are J-point depression 0.05 mV (-0.5 mm) in leads V2 and V3 and -0.1 mV (-1 mm) in all other leads (men and women)

ECG classification

·         Nondiagnostic or normal ECG

·         Nondiagnostic ECG with either normal or nonspecific ST-segment or T-wave changes.

·         ST-segment deviation of 0.5 mm or T-wave inversion of ≤ 0.2 mm

Note:  This classification includes patients with normal ECGs and those with ST-segment deviation of 0.5 mm (0.05 mV) or T-wave inversion of ≤ 0.2 mV.
Circulation. 2010; 122: S787-S817 doi: 10.1161/​CIRCULATIONAHA.110.971028

ECG changes

·         Elevated ST segments

·         Inverted T waves

·         Pathological Q waves

Elevated ST Segments

·         Normal ST segment is isoelectric or flat

·         With injury to the myocardium, the flow of the electrical impulse is changed leading to ST elevation

·         These changes may be evident within a couple of hours after the injury

Elevated ST Segments

NSR with ST elevation

Inverted T Waves

·         The normal T wave is symmetrical and upright

·         Symmetrical inversion of the T wave is caused by myocardial ischemia.

Inverted T Waves

NSR with Inverted T wave

Pathologic Q waves 

·         Normal Q waves are not more than 1 mm deep or wide

·         Pathologic Q waves are > than .04 sec wide and > than 25% of the R wave in the same lead

·         Q waves and elevated ST segments is significant for an acute MI

Pathologic Q waves 

ST Elevation with Pathologic Q Waves