Figure 2. Algorithm developed by Betensky BP et al.15 for OTA ECG localization. If the PVC transition to an R>S occurs later than the SR transition then the PVC origin is the RVOT (100% specificity). If the PVC transition occurs at or earlier than the SR transition (i.e., SR transition lead V3 or later), then the V2 transition ratio is measured. If the transition ratio is <0.6, then RVOT origin is likely. If the transition ratio is ≥0.6, then LVOT origin is likely (sensitivity 95%, specificity 100%).
