During radiofrequency ablation of persistent AF, some patients convert directly to sinus rhythm (SR), some convert to organized atrial tachycardia (AT) while others stay in AF. The factors influencing the above outcomes are largely unknown. Drewitz et al. attempted to evaluate the differences in the clinical and electrophysiological characteristics of patients converting from AF directly to SR or to AT before converting to SR. They studied 95 consecutive patients with persistent AF undergoing ablation for the first time who eventually converted to SR during the procedure. All patients underwent ablation in a stepwise fashion starting with pulmonary vein isolation (PVI). If PVI did not terminate AF, they performed left atrial defragmentation, coronary sinus ablation, right atrial ablation including the superior vena cava in that order till they converted to either AT or SR. If AF terminated to AT, they mapped and ablated as necessary to terminate it into SR. If AF terminated into SR anytime after the PVI, they stopped further ablation.

Of the 95 patients, 40 terminated directly to SR and the rest 55 terminated to AT. Termination of AF was preceded by an increase in the AF cycle length (AFCL) in all patients. Patients who terminated directly to SR were younger, had fewer previous cardioversions, smaller LA size and a higher baseline AFCL. The only independent predictor of AF termination directly to SR was baseline AFCL. After a mean follow-up of 12 months without a blanking period, there were more patients with recurrences in the SR terminated group compared to the AT terminated group (57 vs 38%; p = 0.09). Most people with recurrences underwent re-do ablation after a mean of 6 months. There were more patients in the SR terminated group who required only PV re-isolation during re-do procedure compared to the AT terminated group (53 vs 3%; p < 0.001).

In summary the study with its limitations of a small number attempted to identify a subgroup of patients with persistent AF with a better prognosis. Patients who terminated into SR directly overall fared better and had more features of paroxysmal AF compared to those who terminated into AT. The confounding factor for these positive findings in the study is baseline AFCL. It is being increasingly recognized that AFCL is a marker of the severity of AF. The smaller the AFCL, the worse the AF substrate is. This study adds to the existing evidence that AFCL has prognostic value in predicting AF recurrences after AF ablation. Baseline AFCL should be included in the evaluation while considering AF ablation for persistent AF.

Reference:

Drewitz I, Willems S, Salukhe TV, Steven D, Hoffmann BA, Servatius H, Bock K, Aydin MA, Wegscheider K, Meinertz T, Rostock T. Atrial fibrillation cycle length is a sole independent predictor of a substrate for consecutive arrhythmias in patients with persistent atrial fibrillation. Circ Arrhythm Electrophysiol. 2010 Aug 1;3(4):351-60.

Matsuo S, Lellouche N, Wright M, Bevilacqua M, Knecht S, Nault I, Lim KT, Arantes L, O'Neill MD, Platonov PG, Carlson J, Sacher F, Hocini M, Jaïs P, Haïssaguerre M. Clinical predictors of termination and clinical outcome of catheter ablation for persistent atrial fibrillation. J Am Coll Cardiol. 2009 Aug 25;54(9):788-95.