Slow Fragmented Intraatrial Conduction Post Maze Procedure: Substrate for Intraatrial Reentrant Tachycardi and Marker for Effective Radiofrequency Ablation

The maze procedure is surgical alternative for treating drug refractory atrial fibrillation. Although post-maze atrial fibrillation has been noted, slow intraatrial tachycardias have not been reported. Of 31 maze patients with mean follow-up of 22 ± 9 months, 6 underwent electrophysiologic (EP) testing (9 ± 6 months post-op) for symptoms suggestive of recurrent arrhythmia. Results: Conduction was significantly prolonged through the right compared to the left atrium (167 ± 44 vs 57 ± 10 ms, p < 0.01). However, right atrial effective refractory periods were normal (237 ± 29 ms). Programmed atrial stimulation induced sustained slow intraatrial reentry in two patients (cycle lengths of 420 and 520 ms) and atrial flutter (cycle length 190 ms) in one patient. The slow reentrant tachycardias were successfully ablated with radiofrequency energy in both patients. Neither patient has experienced clinical recurrence after 14 and 9 months. Electrograms at successful ablation sites were markedly fragmented during sinus rhythm, with an apparent reversal of near/far-field activation during tachycardi (see figure). Conclusions: Slow intraatrial tachycardias may be observed in symptomatic post-maze patients. Our findings are consistent with slow conduction and reentry along line of conduction block. Radiofrequency catheter ablation can be curative for these tachycardias.