Background: Complex fractionated electrograms (CFEs) are continuous electrograms (EGMs) of very short cycle length (CL) representing substrate for atrial fibrillation (AF) perpetuation. Ablation of CFEs may result in AF slowing, termination, and prevention, but identifying them can be subjective.
Objective: The purpose of this study was to prospectively assess (1) whether an automated algorithm can identify CFE regions, (2) the acute effects of ablating these regions on AF, and (3) the long-term efficacy as an adjuvant strategy to pulmonary vein antrum isolation (PVAI).
Methods: Thirty-five patients (three centers, 61 +/- 9 years, left atrium [LA] 43 +/- 9 mm, ejection fraction 53% +/- 7%) with symptomatic paroxysmal (n = 21) or persistent (n = 14) AF were studied. A decapolar lasso (2-mm spacing) was used for mapping. A three-dimensional shell of the LA and pulmonary veins (PVs) was created. If not already in AF, AF was induced by burst pacing (with or without isoproterenol). Atrial EGMs during AF were mapped/analyzed using an automated CFE algorithm. The algorithm measures the time between discrete deflections in a local EGM over 5 seconds (based on selectable width and peak-to-peak [>0.03 mV] criteria). The mean CL of the local EGM is projected onto the LA shell as a color-coded display. Regions of CL <120 ms (published criteria) were targeted for ablation/elimination. Atrial fibrillation cycle length (AFCL) and regularity were measured from the CS. After CFE ablation, further ablation was done to achieve complete PVAI.
Results: AF was spontaneous (n = 20) or induced (n = 15) in all patients. CFEs were most commonly found along the septum (97%), anterior LA (97%), PV antra (83%), base of appendage (83%), and annulus (71%). CFE ablation alone prolonged the AFCL (171 +/- 27 vs. 304 +/- 41 ms; P = .03) and regularized AF to left/right flutter (AFL) in 74% of patients. CFE ablation terminated AF/AFL in 19 patients (54%)-the other 16 were cardioverted-and AF became noninducible in 77%. CFE ablation alone did not cause PV isolation (0.1 +/- 0.3 PV isolated/patient). After combined CFE and PVAI ablation, the single-procedure, off-drug success rate was 83% (follow-up 13 +/- 4 months) versus 71% in matched controls who had PVAI alone (P = .045).
Conclusions: CFE ablation guided by an automated algorithm resulted in AFCL prolongation, regularization, and noninducibility in most patients. AF terminated in 54% of cases. PVAI with adjuvant CFE ablation has a high efficacy and may be superior to PVAI alone.