32M with DCM; likely tachycardia induced. ECG shows long RP, narrow complex tachycardia.

EGM shows narrow complex tachycardia with variable VA time. In the last 2 beats, tachycardia CL increases. Change in A-A times precedes change in V-V time. AT is preferred.

EGM: V pacing during tachycardia is unable to conduct to A. Tachycardia continued without interuption. AVRT is excluded.

3D electroanatomical mapping shows earliest signal at the septal area of RA with radial activation pattern.

Signal in the ablation catheter is 40ms earlier than P wave. Ablating here terminated the tachycardia.
The EGM at the successful site is usually >15ms earlier than P wave.