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-mu-g/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 < V1 < V3R V < V4R) (n = 26) and leftward (V2 < V1 < V3R > 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 AlL 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 (< 50%) and high specificity (> 87%) for a such diagnosis. Therefore the routine use of the right chest leads in stress tests soon after acute myocardial infarction provides useful information about the location of the coronary lesions.