Diagnostic value of exercise-induced S-T segment depression in patients with right bundle branch block

The sensitivity of submaximal exercise testing in detecting coronary artery disease in patients with right bundle branch block is not known. Thirty patients were identified who had right bundle branch block, submaximal treadmill exercise tests and selective coronary angiography. Eighteen of these patients were found to have significant coronary artery disease. Treadmill exercise testing was associated with S-T segment depression limited to leads V₁ to V₃ in three patients with coronary artery disease, whereas S-T segment depression was noted in leads V₄ to V₆ in eight patients, all of whom had multivessel coronary artery disease. Among patients without significant coronary artery disease, six had S-T segment depression limited to leads V₁ to V₃ during exercise testing. In this patient population, composed predominantly of men with symptoms of ischemic heart disease, the 12 lead submaximal treadmill exercise test had a sensitivity rate of 69 percent and a specificity rate of 45 percent in detecting coronary artery disease in the presence of right bundle branch block. The specificity of the treadmill test appears to be greater if S-T depression is recorded in leads V₄ to V₆. S-T segment depression limited to leads V₁ to V₃ often represents a false positive exercise test.