Discrimination of ventricular tachycardia from ventricular fibrillation by morphologic analysis of electrograms

To determine whether ventricular tachycardia (VT) and ventricular fibrillation (VF) can be discriminated by time-domain analysis, correlation waveform analysis (CWA) was performed using bipolar intracardiac electrograms of 12 consecutive patients during sinus rhythm (SR) and induced monomorphic VT and VF. Using a best fit template-signal alignment, CWA separated SR from 10/12 VTs (83%) and 12/12 VFs (100%), respectively. The individual variances for VT and VF were significantly different, and a threshold midway between the average variance in VT and VF was a successful discriminant in 11/12 cases (92%). These results suggest that time-domain analysis can discriminate VT and VF from SR, and the magnitude of the variance in VT and VF can be used to distinguish VT from VF