1. Intermediate/low-risk UA
12-Lead ECG Findings
ST elevation or
new or presumably
new LBBB;
strongly suspicious
for injury
ST-elevation MI
(STEMI)
ST depression or
dynamic T-wave
inversion; strongly
suspicious for
ischemia
High-risk unstable
angina/NonST-
elevation MI
(UA/NSTEMI)
Normal or non-
diagnostic changes
in ST segment
or T wave
Intermediate/low-risk UA
Reperfusion
Lytics—PCI
Antiplatelet
Antithrombin
Therapy
Risk
Stratification
Key Concept: Briefly review the principle that the 12-lead ECG is the initial and most important triage tool, and it is abnormal in about 50% of patients with ACS. Stress that the ECG is performed in the prehospital setting or within 10 minutes of ED arrival and interpreted by the senior healthcare professional charged with initiating reperfusion therapy. Discuss the importance of the 3 ECG categories.
Discussion Points: ST-segment depression may be due to high-risk coronary ischemia. If so, these patients require immediate attention and triage. Participants should have already suggested drug therapy. If not, reinforce this initial treatment now.
ST depression or dynamic T wave inversion (non–ST-segment MI or unstable angina): These patients DO NOT BENEFIT FROM AND MAY BE HARMED BY administration of fibrinolytic therapy. In high-risk patients this ECG indicates the need for aggressive antiplatelet therapy (aspirin, heparin, GP IIb/IIIa inhibitor therapy, clopidogrel) and early coronary angiography.
In this patient the ECG shows approximately 1 mm of ST-segment depression. Help participants focus on this abnormality. Ask how ST-segment depression is measured. Most pattern readers DO NOT measure the degree of ST-segment depression; this is usually done by visually comparing it with the PR interval.
The next slide reviews the actual measurement of ST depression. 4