Background: Whether ablation of complex fractionated atrial electrograms (CFAE) modifies atrial fibrillation (AF) by eliminating drivers or atrial debulking remains unknown. This randomized study aimed to determine the effect of ablating different CFAE morphologies compared with normal electrograms (ie, debulking normal tissue) on the cycle length of persistent AF (AFCL).
Methods and results: After pulmonary vein isolation left and right atrial CFAE were targeted, until termination of AF or abolition of CFAE before DC cardioversion. Ten-second electrograms were classified according to a validated scale, with grade 1 being most fractionated and grade 5 normal. Patients were randomly assigned to have CFAE grades eliminated sequentially, from grade 1 to 5 (group 1) or grade 5 to 1 (group 2). An increase in AFCL (mean of left and right atrial appendage) ≥5 ms after a lesion was regarded as significant. CFAE (n=968) were targeted in 20 patients. AFCL increased after targeting 51±35% of grade 1 CFAE, 30±15% grade 2, 12±5% grade 3, 33±12% grade 4, and 8±15% grade 5 CFAE (P<0.01 for grades 1, 2, and 4 versus 5; 3 versus 5, not significant). The proportion of lesions causing AFCL prolongation was unaffected by the order in which CFAE were targeted.
Conclusions: Targeting CFAE is not simply atrial debulking. Ablating certain grades of CFAE increases AFCL, suggesting they are more important in maintaining AF.
Clinical trial registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00894400.