Ablation of atrial fibrillation using an irrigated-tip catheter: open or closed?

Since the advent of radiofrequency (RF) catheter ablation of cardiac arrhythmias, innovations in catheter design and technology have provided the operator with a growing selection of ablation catheters. In contrast to ablation of common supraventricular arrhythmias, where ablation of a well-defined single site results in excellent clinical outcomes, ablation of complex arrhythmias such as atrial fibrillation (AF), atrial flutter, and ventricular tachycardia often requires multiple and larger lesion sets. Because recovery of conduction plays a key role in recurrence of these arrhythmias, it also is important to create transmural lesions that are likely to be permanent. In this issue of the Journal, Golden et al.,1 report clinical outcomes using a closed-irrigatedtip catheter for ablation of AF. RF catheter ablation was performed in 195 patients with paroxysmal (56%) or persistent AF (44%) with a closed-irrigated-tip catheter that had a 3.5-mm tip electrode (Chilli II, Boston Scientific, Natick, MA, USA). RF energy was delivered in a temperature-controlled mode with a target temperature of 40◦C at a maximum power of 35–40 W (25 W along the posterior wall). First, pulmonary vein isolation was performed during AF, followed by a stepwise approach of linear ablation, ablation of complex fractionated electrograms, coronary sinus isolation, and superior vena cava isolation until AF terminated and was not inducible, or the steps were completed with a substantial decrease in AF cycle length. After a 6-week blanking period, recurrence of AF was defined as any symptomatic episode longer than 5 minutes in duration or any documented episode of AF on an electrocardiogram, Holter monitor, or device interrogation for >30 seconds. Patients with a recurrence were offered repeat ablation or antiarrhythmic drug therapy. Follow-up visits were performed at 6, 12, 24, and 36 weeks and at the physician’s discretion