On-Treatment Analysis of CONFIRM1
FIRM-guided therapy has demonstrated success at eliminating rotors and reducing the need for additional Afib treatments including multiple heart ablation procedures.
The study authors hypothesized that ablation of stable atrial fibrillation (AF or Afib) sources, either directly by focal impulse and rotor modulation (FIRM) or coincidentally when anatomical ablation passes through AF sources, may explain long-term freedom of AF.
It is unclear why conventional anatomical AF ablation can be very effective in some patients yet ineffective in others with similar profiles.
The CONFIRM trial2 prospectively showed stable AF rotors or focal sources in 98 of 101 subjects with Afib at 107 consecutive ablation cases. In a 1:2 fashion, subjects received targeted source ablation (FIRM-guided therapy) then conventional ablation, or conventional ablation alone. The authors determined if ablation lesions on electroanatomic maps passed through AF sources on FIRM maps. The only exclusion was a patient’s inability or refusal to provide specific, written informed consent.
- More than half of rotors were outside of the areas typically ablated with traditional PVI (pulmonary vein isolation)
- The successful elimination of rotors was directly correlated with success, namely single-procedure freedom from AF
The eradication of stable AF rotors and focal sources may explain freedom from AF after diverse approaches to heart ablation procedures. Patient-specific AF source distributions are consistent with the reported success of specific anatomical lesion sets, and of widespread ablation. These results support targeting AF sources to reduce unnecessary ablation, and motivate studies on FIRM-only ablation.
- Narayan SM, Krummen DE, Clopton P, Shivkumar K, and Miller JM. Direct or Coincidental Elimination of Stable Rotors or Focal Sources May Explain Successful AF Ablation: On-Treatment Analysis of the CONFIRM Trial. J Am Coll Cardiol. 2013; 60(2):138-47.
- Narayan SM, Krummen DE, Shivkumar K, Clopton P, Rappel W-J, and Miller JM. 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. J Am Coll Cardiol 2012; 60(7):628-3