Previous work has suggested that at higher absolute ventricular fibrillation voltages (AVFVs) the heart is more vulnerable to defibrillation. This study investigated in a canine model whether voltage integration of the AVFV is associated with the defibrillation success rate. In seven animals, repeated defibrillation trials were analyzed using a fixed DC shock (DCS). For each of a total of 84 DCSs, the fibrillation waveform from lead II of the electrocardiogram just prior to DCS was analyzed. The integration of the AVFV waveform was computed over various sample sizes, including 1, 4, 8, 16, 64, and 128 ms. The results suggest that higher values of integrated AVFV over the various window sizes are associated with successful defibrillation.