Surface electrocardiographic patterns and electrophysiologic characteristics of atrial flutter following modified radiofrequency MAZE procedures.
BACKGROUND
The radiofrequency MAZE is becoming a common adjunct to cardiac surgery in patients with atrial fibrillation. While a variety of postoperative arrhythmias have been described following the original Cox-MAZE III procedure, the electrophysiological characteristics and surgical substrate of post-radiofrequency MAZE flutter have not been correlated. We sought to determine the location, ECG patterns, and electrophysiological characteristics of post-radiofrequency MAZE atrial flutter.


METHODS
Nine consecutive patients with post-radiofrequency MAZE flutter presented for catheter ablation 9 +/- 10 months after surgery.


RESULTS
Only one patient (11%) had an ECG appearance consistent with typical isthmus-dependent right atrial (RA) flutter. However, on electrophysiological study, 3/9 patients (33%) had typical right counter-clockwise flutter entrained from the cavo-tricuspid isthmus, despite description of surgical isthmus ablation. Six patients (67%) had left atrial (LA) circuits. These involved the mitral annulus in 5/6 cases (83%) despite description of surgical mitral isthmus ablation in the majority (60%). LA flutters had a shorter cycle length compared with RA flutters (253 +/- 39 msec and 332 +/- 63 msec respectively, P < 0.05). After a mean of 8 +/- 4 months following ablation, 8/9 patients (89%) were in sinus rhythm.


CONCLUSIONS
Up to one-third of post-radiofrequency MAZE circuits are typical isthmus-dependent RA flutters, despite a highly atypical surface ECG morphology. Therefore, diagnostic electrophysiological studies should commence with entrainment at the cavo-tricuspid isthmus in order to exclude typical flutter, regardless of the surface ECG appearance. Incomplete surgical lesions at the mitral and cavo-tricuspid isthmus likely predispose to the development of post-radiofrequency MAZE flutter.
Akar
Joseph G
JG
Division of Cardiology, Department of Medicine, Loyola University Medical Center, Maywood, Illinois 60153, USA. jakar@lumc.edu
Al-Chekakie
M Obadah
MO
Hai
Afroz
A
Brysiewicz
Neil
N
Porter
Michael
M
Varma
Niraj
N
Santucci
Peter
P
Wilber
David J
DJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001282:Atrial Flutter / Q000175:diagnosis* / Q000209:etiology* / Q000601:surgery; D018780:Body Surface Potential Mapping; D017115:Catheter Ablation / Q000009:adverse effects*; D003131:Combined Modality Therapy; D003452:Cryosurgery; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006325:Heart Atria / Q000473:pathology / Q000503:physiopathology; D006349:Heart Valve Diseases / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome