Pseudo-Conduction After Cavotricuspid Isthmus Ablation

BACKGROUND: Bidirectional cavotricuspid isthmus (CTI) block is the procedural endpoint of typical atrial flutter ablation, but pseudo-conduction may mimic residual isthmus conduction. CASE SUMMARY: A 45-year-old man underwent CTI ablation for typical atrial flutter. After linear ablation, a short double-potential interval and simplified differential pacing suggested residual conduction near the inferior vena cava (IVC). Additional ablation at this region failed to change the activation pattern. High-density mapping ultimately confirmed complete CTI block, whereas rapid activation around the IVC reached the lateral right atrium early, creating a pseudo-residual conduction pattern. The patient had no complications and remained free from recurrence during 9-month follow-up. DISCUSSION: Rapid conduction around the IVC may confound conventional criteria for CTI block. TAKE-HOME MESSAGE: High-density mapping may help differentiate true residual conduction from pseudo-conduction and prevent unnecessary ablation.