Automated treatment of arrhythmia utilizing an electrotherapy device. Time-coordinated applications of medium-voltage therapy (MVT) followed by high-voltage therapy (HVT) include a first MVT waveform to a first target region and a second MVT waveform to a second target region, such that the HVT is synchronized relative to a first compression cycle corresponding to activation of the first target region, and to a second compression cycle corresponding to activation of the second target region resulting from the administration of the MVT.