More FIRM Research: Mapping System Falls Short (Again)
Background: FIRM stands for ‘Focal Impulse and Rotor Modulation’; The FIRM mapping and ablation system uses a basket catheter, a panoramic contact-mapping tool by Topera/Abbott Laboratories. Rotors (rotational circuits or focal sources) are underlying drivers that sustain or perpetuate an A-Fib signal after it has been triggered (like an echo).
A three-center 2015 study (Gianni) used FIRM-guided only ablation on 29 patients with persistent or long-standing persistent A-Fib. The centers were:
• The Texas Cardiac Arrhythmia Institute, St. David’s Medical Center, Austin, TX, USA
• The Heart Center Bad Neustadt, Bad Neustadt, Germany
• Baptist Health, Lexington, KY, USA
Undergoing FIRM mapping, 20 patients had persistent A-Fib and 9 patients had long-standing persistent. Doctors found 4 rotors (on average) per patient (with 62% coming from the left atrium) and 1 focal impulse. All these signal sources were successfully ablated.
Follow-up Ablation Results
After a mean of 5.7 months of follow-up, single procedure freedom from A-Fib/Flutter without antiarrhythmic drugs was a low 17%.
Researchers concluded that the FIRM system was not effective in returning patients to normal sinus rhythm (or alternatively moving from the chaotic A-Fib rhythm to a more regular rhythm such as A-Flutter). And only ablating FIRM-identified rotors did not prevent recurrence (i.e., return of A-Fib).
Other Research on the FIRM System
This study confirms the January 2015 AF Symposium presentation, Critical Analysis of the FIRM Mapping System, by Dr. Ravi Mandapati of Loma Linda University,
From a different perspective, Dr. Vivek Reddy offers a real world application of the FIRM system (advantages and problems). See the 2016 AF Symposium presentation: Two Challenging, Difficult Catheter Ablation Cases.
Bottom line for Patients
Even though the FIRM mapping and ablation system seems to currently have built-in limitations, master EPs still use the FIRM basket mapping catheter because it provides a great deal of important information very quickly. It is especially useful in cases of Persistent A-Fib.