Role of Epicardial Mapping and Ablation for Redo Procedure in Patients With Non-paroxysmal Atrial Fibrillation: a Prospective Randomized Trial

Atrial electrical activity during atrial fibrillation depends on the distribution of myocardial tissue. Circumferential and longitudinal muscular bundles are multi-level crossing across the entire thickness of atrial wall. At radiofrequency catheter ablation for atrial fibrillation, transmural lesions are important to reduce the arrhythmogenic substrates and to prevent recurrence of scar-related atrial tachyarrhythmias.

Radiofrequency ablation applying electric current depends on impedance between patch and the tip electrode of a catheter. Increased impedance results in increased tissue heating, following an irreversible damage. However, overheating limits to create deep lesion formation because an increased impedance impedes the energy delivery to tissue. Furthermore, prolonged ablation time may result in severe complications, such as steam pop, cardiac perforation, and char formation. Therefore, both endocardial and epicardial ablations may be more effective to create a transmural lesion compared with only endocardial ablation.

Organized atrial tachycardia is common in patient who underwent ablation for atrial fibrillation. Activation mapping for atrial tachycardia is critical for ablating an isthmus. However, when the amplitude of endocardial potentials after previous ablations is decreased as system does not detect, summation of data from endocardium may give us wrong information about atrial tachycardia. Data from epicardial potential during tachycardia may be helpful to terminate a tachycardia.

We aimed to assess the benefit of epicardial mapping and ablation in patients with recurred atrial tachyarrhythmias after single procedure for atrial fibrillation. We hypothesize that both endocardial and epicardial approach is superior to only endocardial approach with regards to clinical recurrence. Participants are randomized into a hybrid approach or an endocardial approach.