Teaching Rounds in Cardiac Electrophysiology How to Approach Reentrant Atrial Tachycardia After Atrial Fibrillation Ablation

A 63-year-old male patient was admitted for catheter ablation of persistent atrial fibrillation (AF). On echocardiography, the left atrial (LA) size was 48 mm and the left ventricular function was normal. After electric cardioversion, ipsilateral pulmonary veins (PVs) were circumferentially ablated in sinus rhythm using double-Lasso (Lasso, Biosense Webster, Diamond Bar, CA) technique.1–3 Both ipsilateral PVs were simultaneously isolated. Two years later, the patient was admitted for the ablation of recurrent, drug-resistant atrial tachycardia (AT) (Figure 1A). The baseline tachycardia cycle length (TCL) was 350 ms. A 20-pole mapping catheter (Irvine Biomedical Inc, Irvine, CA) was inserted through the right jugular vein and positioned in the coronary sinus (CS). An 8-mm-tip ablation catheter (Japan Lifeline Inc, Tokyo, Japan) was advanced into the LA through a transseptal puncture. Mapping during AT revealed the resumption of conduction in the right PVs. On entrainment mapping, the post pacing interval (PPI-TCL) was found to be 120, 70, 56, and 10 ms at the low lateral right atrium, anterior LA, bottom of LA, and left septum near the right PVs, respectively. On activation mapping using a 3D electroanatomic mapping system (Carto, Biosense Webster), earliest atrial activation was observed on the roof of right superior vein and the latest at the bottom of right inferior vein. Successful entrainment from the superior and inferior veins revealed that both sites were within the tachycardia circuit (Figure 1B and 2A). Entrainment from the LA septum near the right PVs demonstrated that septal myocardium was also a part of the reentrant circuit. Furthermore, P-wave morphology during entrainment pacing from near the roof of the right superior vein was identical to that observed during tachycardia (Figure 2B). Mapping near the site of the earliest atrial activity on the 3D map identified a 140-ms-long, fractionated and low-amplitude signal (0.044 mV, Figure 3A and 3B). After 4.5 seconds of radiofrequency (RF) delivery at that site, the tachycardia terminated (Figure 3C). Induction attempts from the right PVs were negative. In sinus rhythm, a gap in the circumferential PV lesion was observed at the site that showed latest activation during tachycardia (Figure 4A and 4B). It was successfully ablated, ensuing in simultaneous right inferior and superior PVs isolation (Figure 4C). The patient has remained free from any arrhythmia for 3 years.