This is a prospective randomized controlled trial that compares the conventional stepwise approach with a new sequential substrate ablation approach for persistent atrial fibrillation.

A total number of 100 patients with persistent AF were randomized to receive either conventional stepwise ablation (conventional group) or a sequential substrate ablation (substrate group), both with the endpoint of AF termination. All patients were in AF before the procedure. The sequential substrate ablation consisted of pulmonary vein isolation (PVI) followed by cardioversion and linear ablation at the mitral isthmus, left atrial roof and cavotricuspid isthmus in order to modify the AF substrate. After achievement of bidirectional block, AF was re-induced and electrogram-based ablation was performed to achieve AF termination to sinus rhythm (SR). Endpoints are single-procedure outcome and total amount of RF ablation time required to terminate AF by electrogram-guided ablation.

Inclusion Criteria:

• persistent atrial fibrillation lasting longer than 3 months
• no previous ablations
• at least 1 electrical cardioversion

Exclusion Criteria:

• non-persistent atrial fibrillation
• previous ablation procedures