Value of lead V4R in exercise testing to predict proximal stenosis of the right coronary artery

To assess the value of lead V4R during exercise testing for predicting proximal stenosis of the right coronary artery, 107 patients were studied. In all patients, a Bruce exercise test with the simultaneous recording of leads I, II, V4R, V1, V4 and V6 was followed by coronary angiography. Apart from registering ST segment changes in the conventional leads, all patients were classified according to absence or presence of an ST segment deviation of 1 mm or greater in lead V4R. Seventy-nine of the 107 patients were studied because of inadequate control of angina pectoris. Seven patients had had myocardial infarction before 40 years of age. Twenty-one patients were analyzed because of severe cardiac arrhythmias. In the 46 patients who had a previous myocardial infarction, the infarct location was inferior in 28 and anterior in 18. Seven of the 14 patients without myocardial infarction and significant proximal stenosis in the right coronary artery showed an ST segment deviation of 1 mm or greater in lead V4R during exercise. This was also observed in 11 of 18 patients with an old inferior wall infarction and proximal occlusion of the right coronary artery. None of the 53 patients without significant proximal stenosis in the right coronary artery showed exercise-related ST segment changes in lead V4R. Exercise-related ST segment deviation in lead V4R had a sensitivity of 56%, a specificity of 96% and a predictive accuracy of 84% in recognizing proximal stenosis in the right coronary artery. These observations indicate that the recording of lead V4R is of value for predicting or excluding proximal stenosis in the right coronary artery.