Figure 1 A: Surface electrocardiogram ( ECG) at baseline. B: Intracardiac ECG at baseline. C: Surface ECG during AT. D: Intracardiac ECG during atrial tachycardia (AT). E: The activation map during AT. Yellow arrows indicate the suspected tachycardia circuit. CS, coronary sinus; LAA, left atrial appendage; LPV, left pulmonary vein; MA, mitral annulus; PPI, post pacing interval; TCL, tachycardia cycle length.