Influence of right ventricular ischemia on precordial ST depression during right coronary artery occlusion.

To determine the cause of precordial ST depression in acute inferior myocardial infarction, we evaluated the relationship between precordial ST deviation and ventricular involvement. Forty-nine patients who were admitted to the hospital with an acute inferior myocardial infarction, and 60 patients who were treated with elective angioplasty to the right coronary artery, were analyzed. All patients had single vessel disease and were divided into 2 groups (A and B) according to the site of the lesion. Patients in group A had a lesion proximal to the largest right ventricular branch, while in group B the lesion was distal to that branch. There were no differences in inferior ST elevation between the 2 groups, but precordial ST segments were more depressed in group B than in group A. A significant correlation was observed between inferior and precordial ST deviation in group B, but not in group A. These results were similar in patients with myocardial infarction and in those treated by angioplasty. These results suggest that precordial ST depression in an evolving inferior infarction is due to reciprocal ST deviation which reflects inferoposterior involvement. In addition, when inferior infarction is accompanied by right ventricular involvement the precordial ST depression is lessened.