BACKGROUND Atrial tachycardias (ATs) including atrial fibrillation (AF) are common arrhythmias occurring late after Cox Maze procedure and their management is challenging.

OBJECTIVE The purpose of this study was to determine the electrophysiological mechanisms of ATs in patients with prior Cox Maze procedure during heart surgery and the long-term outcomes of catheter ablation.

METHODS We studied 60 consecutive patients (mean age  56± 11.6 years;  48 men (80 %)) with prior Maze procedure during heart surgery who presented with recurrence of atrial arrhythmia postoperatively between 2010 and 2017 in our clinic. All patients had a concomitant operation, most commonly either a mitral-valve procedure (60%), an aortic-valve procedure (24%) or coronary artery bypass grafting (13%) or a combination.

Organized atrial flutter was clinically documented in 40 patients (66%) before the electrophysiological study, whereas 14 (24%) patients presented in AF. In the remaining 6 (10%) patients AT was inducible at the beginning of the procedure. A total of 60 patients had 72 ATs that were mapped; 51 (70%) had a left atrial (LA) origin and 21 (30%) had a right atrial (RA) origin. Of the 72 ATs, a total of 16 (22%) had a focal mechanism, with 9 (56%) having an LA origin and 7 (44%) having an RA origin. The predominant circuit were perimitral (n=18), LA-roof (n=14), right pulmonary veins/LA septum (n=4) and cavotrikuspid isthmus (n= 11). In 56 (93%) patients > 1 pulmonary vein reconnection was evident and therefore treated with a circumferential re-isolation. Over a follow-up period of 18 months 38 (63%) patients were free from any arrhythmia whereas AT recurred in 20 (33%) patients. 2 patients presented with atrial fibrillation during the follow-up.

CONCLUSION: Left atrial macroreentry is the predominant AT mechanism in patients with prior Cox Maze procedure during concomitant heart surgery. Pulmonary vein reconnection is frequently observed in patients after Cox Maze procedure.