Correlation between ST elevation and Q waves on the predischarge electrocardiogram and the extent and location of MIBI perfusion defects in anterior myocardial infarction.

Background: The common electrocardiographic subclassification of anterior acute myocardial infarction (AMI) is not reliable in presenting the exact location of the infarct. We investigated the relationship between predischarge electrocardiographic patterns and the extent and location of perfusion defects in 55 patients with first anterior AMI.

Methods: Predischarge electrocardiogram was examined for residual ST elevations and Q waves which were correlated with technetium-99m-sestamibi function and perfusion scans.

Results: Patients with ST elevations in V2-V4 and Q waves in leads V3-V5 had worse global perfusion scores. Perfusion defects in the apex inferior segment were significantly less frequent in patients with Q waves in leads I and aVL (11% vs 54%, P = 0.027; and 22% vs 60%, P = 0.011, respectively). Patients with Q wave in aVF had more frequently involvement of the apex inferior segment (80% vs 40%; P = 0.035). Patients with Q wave in lead II had significantly more frequent perfusion defects in the inferior wall. ST elevation in V3 and V4 was associated with perfusion abnormalities of the infero-septal segments. ST elevation in V5 and V6 and Q wave in V5 were associated with regional perfusion defects in apical inferior segment (73% vs 30%, P = 0.002), extending into the mid inferior segment (55% vs 18%, P = 0.005 for Q wave in V5). Q wave in lead aVL is associated with less apical and inferior involvement. Q waves in leads II and aVF are a sign of inferior extension of the infarction.

Conclusions: Residual ST elevation in leads V3 and V4 are more frequently associated with involvement of the apical-inferoseptal segment rather than the anterior wall. Residual ST elevation and Q waves in V5 are related to a more inferior rather than a lateral involvement.