Treatment of Atrial Fibrillation by the Ablation of Localized Sources: CONFIRM (Conventional Ablation for Atrial Fibrillation With or Without Focal Impulse and Rotor Modulation) Trial

Study Questions:

How effective is a radiofrequency catheter ablation (RFCA) strategy of focal impulse and rotor modulation (FIRM) in patients with atrial fibrillation (AF)?


The subjects of this prospective, nonrandomized study were 92 patients (mean age 62 years) with AF (persistent in 71%) who underwent 107 ablation procedures, either conventional RFCA with (n = 36) or without (n = 71) FIRM-guided ablation. The right and left atria were mapped during AF with a 64-electrode basket catheter, and signal analysis was performed to identify focal sources and rotors. Conventional ablation consisted of wide-area pulmonary vein isolation plus a left atrial roof line if the AF was persistent. Recurrent AF was identified in most patients with implanted loop recorders or pacemakers. The acute endpoint was AF termination or slowing by ≥10%. The long-term endpoint was freedom from AF after a single procedure.


A mean of 2.1 focal sources or rotors (76% in the left atrium, 24% in the right atrium) were identified in 97% of patients. Acute efficacy was significantly higher with FIRM ablation alone (86%) than with conventional RFCA (20%). After a median of 273 days, long-term efficacy also was significantly higher in the FIRM ablation group (82%) than in the conventional group (45%).


Localized sources can be identified in almost all patients with AF, and RFCA of these sources significantly improves the results of AF ablation.


This highly intriguing and seminal study demonstrates for the first time in humans that localized rotors or focal impulse sources are common mechanisms of sustenance of paroxysmal and persistent AF.

Clinical Topics: Arrhythmias and Clinical EP, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias

Keywords: Pulmonary Veins, Atrial Fibrillation, Catheter Ablation

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