Prediction of the effectiveness of long term β blocker treatment for dilated cardiomyopathy by signal averaged electrocardiography

Objective—To determine whether the effectiveness of long term β blocker treatment for idiopathic dilated cardiomyopathy can be predicted by signal averaged electrocardiography (ECG). Patients—31 patients with dilated cardiomyopathy and without bundle branch block were included in a retrospective study and 16 in a prospective study. Methods—A signal averaged ECG was recorded before β blocker treatment, and three variables were measured from the vector magnitude: QRS duration, root mean square voltage for the last 40 ms (RMS40), and duration of the terminal low amplitude signals ( 20 µV, LAS40