A. Total of 1 mm ST elevation in V1-V3 in a male > 40 years old.
B. Total of 0.5 mm ST elevation in aVF and lead III in female > 40 years old
C. Total of 2 mm ST elevation in V2-V3 in a male < 40 years old
D. Total of 1.5 mm ST elevation in lead V2-V3 in a female > 40 years old
A total of 1 mm of ST elevation in 2 contiguous leads is required to diagnose STEMI, however there are two major exceptions.
1. Anterior STEMI requires 2 mm of ST elevation in V2 and V3 in men > 40 years old according to the ACC/AHA definition. A total of 2.5 mm is required in men < 40 years old and only 1.5 mm required in women.
2. Posterior STEMI frequently has ST depression in V1-V3 instead of elevation since the vectors are completely reversed. If a posterior ECG were obtained, ST elevation will be seen in V7-V9, although sometimes subtle. Since these posterior changes occur from coronary thrombosis and urgent treatment is needed, it is classified as a STEMI.