Background: Atrioventricular nodal reentrant tachycardia (AVNRT) is a common form of regular supraventricular tachycardia, and catheter ablation targeting the slow pathway is an established treatment strategy. Three-dimensional voltage mapping of Koch’s triangle may facilitate identification of the presumed slow-pathway region by demonstrating a low-voltage bridge (LVB) and may provide additional guidance for ablation target selection.

Case Summary: A 58-year-old man with a history of hypertension presented to the emergency department with palpitations. On admission, his blood pressure was 115/75 mmHg and heart rate was 180 beats/min. A 12-lead electrocardiogram demonstrated a regular narrow-QRS tachycardia, which was terminated with intravenous adenosine, restoring sinus rhythm. An electrophysiological study was subsequently performed using a two-catheter approach and the EnSite three- dimensional electroanatomic mapping system. Supraventricular tachycardia was induced and diagnosed as AVNRT based on electrophysiological findings. Three-dimensional voltage mapping of Koch’s triangle demonstrated a discrete LVB in the inferior region adjacent to the coronary sinus ostium, corresponding to the presumed slow-pathway region. Radiofrequency ablation was performed targeting the LVB. Following ablation, AVNRT was no longer inducible during programmed stimulation.

Conclusion: Three-dimensional voltage mapping may allow visualization of a low-voltage bridge within Koch’s triangle and provide additional guidance for slow-pathway localization during AVNRT ablation. This case demonstrates the feasibility of an EnSite-guided LVB-targeted radiofrequency ablation strategy using a two-catheter approach, with successful acute elimination of AVNRT inducibility.