FIRM-Guided Ablation for Atrial Fibrillation

Study Questions:

What are the outcomes of radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) guided by focal impulse and rotor mapping (FIRM)?


This was a single-center retrospective study of 170 consecutive patients (mean age 59 years) referred for RFCA of AF (paroxysmal 37%, persistent in 31%, and longstanding persistent in 32%). Ablation was guided by electrograms recorded in both atria with a 64-pole basket catheter then analyzed using proprietary software to identify focal sources and rotors. Pulmonary vein isolation (PVI) was performed in 95% of patients after FIRM-guided ablation. The primary endpoint was freedom from AF after a single procedure.


A mean of 3.5 rotors/focal sources per patient were identified, 46% of which were in the right atrium and 86% of which were rotors. RFCA of the sources resulted in conversion of AF to sinus rhythm in 22% of patients and to atrial flutter/tachycardia (AFl/ATach) in 17% of patients. Overall single-procedure freedom from AF/AFl/ATach off antiarrhythmic medications at 1 year was 70% (77% for paroxysmal AF, 75% for persistent AF, and 57% for longstanding persistent AF).


The acute results and 1-year outcomes of FIRM-guided RFCA provide strong support that bi-atrial rotors and focal sources are important mechanisms of AF.


Termination of AF after only a few minutes of RFCA in approximately 40% of patients provides compelling evidence that the FIRM system is capable of identifying critical sources of AF. But because PVI also was performed in almost all patients, the clinical efficacy of stand-alone FIRM-guided ablation remains unclear. Furthermore, there continues to be no obvious explanation for why some highly-experienced operators have reported poor outcomes using this approach.

Clinical Topics: Arrhythmias and Clinical EP, Prevention, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias

Keywords: Anti-Arrhythmia Agents, Arrhythmias, Cardiac, Atrial Fibrillation, Atrial Flutter, Catheter Ablation, Primary Prevention, Pulmonary Veins, Tachycardia, Tachycardia, Supraventricular, Treatment Outcome

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