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 m yocardial infarction, we evaluated the relationship between precordial ST deviation and ventricular involvement. Forty-nine patients who wer e admitted to the hospital with an acute inferior myocardial infarctio n, and 60 patients who were treated with elective angioplasty to the r ight coronary artery, were analyzed. All patients had single vessel di sease and were divided into 2 groups (A and B) according to the site o f 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 t hat 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 inf erior and precordial ST deviation in group B, but not in group A. Thes e results were similar in patients with myocardial infarction and in t hose 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, whe n inferior infarction is accompanied by right ventricular involvement the precordial ST depression is lessened.