Multicentre safety of adding Focal Impulse and Rotor Modulation (FIRM) to conventional ablation for atrial fibrillation

Focal Impulse and Rotor Modulation (FIRM) uses 64-electrode basket catheters to identify atrial fibrillation (AF)-sustaining sites for ablation, with promising results in many studies. Accordingly, new basket designs are being tested by several groups. We set out to determine the procedural safety of adding basket mapping and map-guided ablation to conventional pulmonary vein isolation (PVI).

We collected 30 day procedural safety data in five US centres for consecutive patients undergoing FIRM plus PVI (FIRM-PVI) compared with contemporaneous controls undergoing PVI without FIRM. A total of 625 cases were included in this analysis: 325 FIRM-PVI and 300 PVI-controls. FIRM-PVI patients were more likely than PVI-controls to be male (83% vs. 66%, P < 0.001) and have long-standing persistent AF (26% vs. 13%, P < 0.001) reflecting patients referred for FIRM. Total ablation time was greater for FIRM-PVI (62 ± 22 min) vs. PVI-controls (52 ± 18 min, P = 0.03). The complication rate for FIRM-PVI procedures (4.3%) was similar to controls (4.0%, P = 1) for both major and minor complications; no deaths were reported. The rate of complications potentially attributable to the basket catheter was small and did not differ between basket types (Constellation 2.8% vs. FIRMap 1.8%, P = 0.7) or between cases in which basket catheters were and were not used (P = 0.5). Complication rates did not differ between centres (P = 0.6).

Procedural complications from the use of the basket catheters for AF mapping are low, and thus procedural safety appears similar between FIRM-PVI and PVI-controls in a large multicentre cohort. Future studies are required to determine the optimal approach to maximize the efficacy of FIRM-guided ablation.