Detecting exercise-induced ischemia in left bundle branch block using the electrocardiogram

We compared 12-lead electrocardiographic changes during exercise in 41 patients with left bundle branch block; 7 were nonischemic and 34 had coronary artery obstruction > or =70% as detected by angiogram. ST depression of > or =0.5 mm from baseline when measured at the J point in leads II and AVF (p=0.004) and an increase of R-wave amplitude in lead II (p=0.05) significantly identified ischemia.