Introduction: Atrial tachycardia (AT) with cycle length alternans occurring after atrial fibrillation ablation has not been previously described. Methods: Among 66 patients with left AT, stable AT with 2 alternating cycles was registered in 5 cases. Activation mapping of both alternating cycles was performed in all 5 patients. Entrainment and fractionated electrogram mappings were also carried out. Results: Among 10 AT cycles, activation maps suggested underlying mechanism of 5 cycles (50%) in 3 patients. Entrainment pacing was helpful in 2 patients (confirmed mechanism of 2 AT cycles). Catheter ablation successfully terminated AT in all 5 patients: ablation of sites with fractionated potentials in 4 patients and mitral isthmus ablation in 1 patient. Conclusion: Consecutive activation mapping of both AT cycles is feasible for mechanism determination in some patients. The results of our small study suggest that fractionated electrogram-guided ablation might be a reasonable approach for termination of this type of AT.

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Keywords Atrial fibrillation, Atrial tachycardia, Catheter ablation, Electroanatomical mapping, Fractionated electrogram, Left atrium, Unmappable tachycardia
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Journal Journal of Electrocardiology
Mikhaylov, E, Szili-Torok, T, Abramov, M, & Lebedev, D. (2011). Ablation of left atrial tachycardia with cycle length alternans after atrial fibrillation ablation: Significance of fractionated electrogram mapping. Journal of Electrocardiology, 44(2), 164–170. doi:10.1016/j.jelectrocard.2010.11.002