A 33-year-old male who underwent surgery for Tetralogy of Fallot presented with atrial flutter. Electrophysiology study revealed concealed entrainment along the mid lateral right atrium with postpacing interval shorter than the tachycardia cycle length. Ablation at this site terminated the tachycardia. The presence of shorter PPI than TCL was due to a large virtual electrode leading to downstream capture of far field tissue. This case demonstrates that sites showing PPI shorter than TCL are in a slow conducting narrow critical isthmus and hence constitute good ablation targets.
Keywords: PPI‐TCL; ablation; atrial flutter; entrainment; narrow isthmus.
© 2021 The Authors. Journal of Arrhythmia published by John Wiley & Sons Australia, Ltd on behalf of the Japanese Heart Rhythm Society.