Stress-induced ST segment shift in leads V3R and V4R after acute myocardial infarction.

A total of 107 patients with acute myocardial infarction underwent a dobutamine stress test and received increasing doses of the drug (5, 10, 15, 20, and up to 40 micrograms/kg/min). Coronary angiography was performed within the first month. The 12 conventional ECG leads plus the right chest leads V3R and V4R were recorded under basal conditions and after each dose of dobutamine. In 51 patients (group A) there was an ST shift greater than or equal to 0.5 mm in the right chest leads, with two different patterns: rightward (V2 less than V1 less than V3R V less than V4R) (n = 26) and leftward (V2 less than V1 less than V3R greater than V4R) (n = 25). In 56 patients (group B) no ST shift in the right chest leads was induced. An ST segment elevation greater than or equal to 0.5 mm in V4R was 43% sensitive and 86% specific for the detection of proximal right coronary artery disease. Four subgroups were established in group A: A1R, rightward ST elevation (n = 23); A1L, leftward ST elevation (n = 12); A2R, rightward ST depression (n = 3); and A2L, leftward ST depression (n = 13). Group A1R had predominantly inferior infarcts and right coronary artery stenoses, group A1L had predominantly anterior infarcts and left anterior descending coronary stenoses, and group A2L had posteroinferior infarcts and right or left circumflex stenoses, all of them with low sensitivity (less than 50%) and high specificity (greater than 87%) for a such diagnosis.(ABSTRACT TRUNCATED AT 250 WORDS)