Relation of T-wave polarity in precordial V1 lead to right or left circumflex coronary pathoanatomy in acute inferior myocardial infarction.

OBJECTIVE

To test the hypothesis that right ventricular (RV) involvement in inferoposterior wall acute myocardial infarction (AMI) may affect precordial T-wave polarity, relation of T-wave polarity in lead V1 to right (RCA) or left circumflex (LCX) coronary pathoanatomy was examined.

METHODS

The study population included the patients with initial inferoposterior wall AMI due to RCA (n = 61) or LCX (n = 19) occlusion within 5 h of symptom onset and 100 normal controls. The patients with RCA disease were further divided into four subgroups based on the site of coronary occlusion and the direction of the ST shift in lead V1: group A1 (n = 27), proximal RCA occlusion with isoelectric or elevated ST segment; group A2 (n = 7), proximal occlusion with ST depression; group B1 (n = 8), distal RCA occlusion with isoelectric or elevated ST segment; group B2 (n = 19), distal occlusion with ST depression. Presence or absence of an upright T wave in lead V1 (> or = 0.15 mV) was evaluated.

RESULTS

The patients with proximal RCA disease showed a higher incidence of upright T wave (71 percent) than the controls (27 percent) (p < 0.001), patients with LCX disease (26 percent) (p < 0.01), and those with distal RCA disease (19 percent) (p < 0.001). Among the four subgroups of RCA disease, the incidence of upright T wave was highest in group A1 (90 percent), lowest in group B2 (6 percent), and intermediate in controls (27 percent) (p < 0.001) for group A1 vs controls, and p < 0.05 for controls vs group B2).

CONCLUSIONS

These findings suggest that concomitant RV involvement in inferoposterior wall AMI modifies T-wave polarity of lead V1, which is ordinarily expected to be reciprocally drawn to negativity when infarct is limited to the inferoposterior wall of the left ventricle, to the positivity.