Key result
In patients with post-radiofrequency MAZE flutter, 33% had typical isthmus-dependent right atrial flutters despite atypical ECGs, and left atrial flutters had shorter cycle lengths (P<0.05).
Observational (n=9)
Up to one-third of post-radiofrequency MAZE circuits are typical isthmus-dependent right atrial flutters despite atypical surface ECG morphology, highlighting the need for cavo-tricuspid isthmus entrainment during EP studies.
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May support cavo-tricuspid isthmus entrainment in post-MAZE flutter despite atypical ECGs; hypothesis-generating and requires validation in larger cohorts.
INTRODUCTION: 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. CONCLUSION: 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.
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Akar et al. (2007) conducted an observational in Post-radiofrequency MAZE atrial flutter (n=9). Post-radiofrequency MAZE flutter was evaluated on Location, ECG patterns, and electrophysiological characteristics of post-radiofrequency MAZE atrial flutter. In patients with post-radiofrequency MAZE flutter, 33% had typical isthmus-dependent right atrial flutters despite atypical ECGs, and left atrial flutters had shorter cycle lengths (P<0.05).
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