Complex fragment atrial electrograms (CFAEs) are fractionated or discrete atrial wave fronts that frequently mapped in chronic atrial fibrillation (CAF). The CFAEs areas represent slow conduction and/or functional blocks that play substrate role in AF. Compared with the limited efficacy of pulmonary veins (PVs) oriented ablation strategy for CAF, few attempts of adjunctive ablation on CFAEs gain promising outcome. We hypothesized that CFAEs, not PVs, are the ideal ablation targets for CAF.