We studied consecutive patients with first inferior (15), lateral (9), or inferolateral (21) MI with reference to contrast enhanced cardiac magnetic resonance (CE-CRM). We measured the R-wave amplitude and duration, the R/S ratio, and the T-wave amplitude and polarity in leads V1 and V2. The specificity of the V1 criteria for lateral MI, that is, R/S amplitude ratio 1 or greater and R duration 40 milliseconds or longer, is very high but its sensitivity is low. We defined 2 new criteria, R/S of 0.5 or greater and R amplitude in V1 greater than 3 mm, with each achieving a sensitivity of 73.3 % and specificity of 93.3 % for lateral/inferolateral MI location.
(1) New ECG criteria for lateral MI (R/S ratio in V1 ≥0.5 and R amplitude in V1 >3 mm) present very high specificity and lower but very acceptable sensitivity for lateral MI. (2) New criteria based on R waves in V2 or T waves in V1 to V2 do not discriminate between inferior and lateral MI. (3) The classical criteria (R/S amplitude ratio ≥1 and R duration ≥40 ms in V1) attain very high specificity but much lower sensitivity than the new criteria.