Reproducibility of measurements of ventricular activation time using the signal-averaged Frank vectorcardiogram

Interobserver and day-to-day variability in detecting delayed potentials and in measuring duration of ventricular depolarization using the signal-averaged Frank vectorcardiogram were investigated in 20 patients, 12 with and 8 without ventricular tachycardia (VT). No patients were taking antiarrhythmic medications, digoxin or β blockers at the time of study. The presence of delayed potentials and duration of ventricular activation were measured 2 times a mean of 5 days apart by 2 observers. Analysis of variance showed no significant interobserver variability in ventricular activation time. Day-to-day differences In ventricular activation times were small in patients without VT, none of whom had delayed potentials at either study. Delayed potentials were present In all 12 patients with VT at the first recording and in 11 at the repeat recording. However, significant (p