Optimal interpretation of the supine exercise electrocardiogram in patients with right bundle branch block

A detailed analysis of the exercise ECG was performed in 82 patients with right bundle branch block who underwent supine exercise equilibrium radionuclide angiography. The sensitivity and specificity of each individual electrocardiographic lead for the detection of a positive radionuclide angiogram was determined. Leads V₅ and V₆ had a sensitivity of 58 percent and a specificity of 89 percent. The limb leads and lead V₄ had a lower sensitivity, but an equivalent specificity. Leads V₁ and V₃ each had a clearly lower specificity that ranged from 56 to 67 percent. Receiver operating characteristic curve analysis demonstrated that the optimal interpretation of the exercise ECG included the limb leads and V₄ to V₆, but not V₁ to V₃. The results of coronary angiography in the subset of 16 patients who underwent this procedure confirmed these findings.