This prospective, randomized study aims to compare the impact of ablation of perimitral flutter only versus cardioversion and repeat isolation of pulmonary veins with ablation of additional triggers, on procedure outcome.

Background: In recent years, catheter ablation has been accepted as the treatment-of-choice for drug-refractory atrial fibrillation (AF). It is centered around isolating pulmonary veins (PVs) and its success rate in curing AF is very high (56%-85%) (1). However, despite isolation of this dominant source of triggers, recurrent tachyarrhythmia is the major complication of this procedure with peri-mitral atrial flutter (PMFL) being the most common macro-reentrant arrhythmia in context of AF ablation (2). These often drug-refractory arrhythmias are frequently associated with more severe symptoms than the original AF (3) and warrant the necessity for redo-ablation.

This study aims to compare the impact of two different redo-ablation strategies on the procedure outcome; (1) ablation of the perimitral flutter only and (2) cardioversion and repeat isolation of pulmonary veins (PV) with ablation of additional triggers.

Study method: A total number of 65 AF patients presenting for redo-ablation and PMFL will be randomized to perimitral flutter ablation only or cardioversion and re-isolation (PVI) plus ablation of additional triggers. Additional triggers will be identified with the help of post-ablation drug provocation with isoproterenol. Patients will enter a follow-up period of 12 months after the ablation procedure, when they will be monitored for recurrence of arrhythmia detected either by in-clinic or remote device interrogation at 1, 3, 6 and 12 month post-procedure.

Inclusion Criteria:

• Patients with previous AF ablation presenting with PMFL and recurrent AF
• Age: 18- 75 years
• Willingness and ability to give written informed consent
• Therapeutic INR for at least 4 weeks prior to the procedure

Exclusion Criteria:

• Reversible causes of AF such as pericarditis and hyperthyroidism
• Documented intra-atrial thrombus, tumor or any other abnormality which prevents easy catheter manipulation
• Enrollment in another clinical study
• Any other terminal illness