Thermal and Non-Thermal Energies for Atrial Fibrillation Ablation

Abstract

The cornerstone of ablative therapy for atrial fibrillation (AF) is pulmonary vein isolation (PVI). Whether PVI should be added with additional lesions in persistent atrial fibrillation (PerAF) or for any post-ablative recurrent AF is a matter of debate. Whatever the ablative strategy, it must determine the choice of energy source to achieve the most durable lesion sets with the least likelihood of complications. Radiofrequency (RF) is the most studied thermal ablation technique. It can be combined with high-density electroanatomic mapping and can be used for both pulmonary and extrapulmonary atrial ablation. Cryoenergy is at least as effective as radiofrequency for PVI; it is rapid, relatively safe, and has a steep learning curve. Therefore, it has been proposed as a first-line approach for PVI-only procedures. More recently, a non-thermal technique based on the application of pulsed direct current (Pulsed Field Ablation-PFA) has been introduced. PFA causes cell death by opening cell membrane pores (electroporation) without a significant increase in tissue temperature. It is fast and does not alter the extracellular matrix as thermal techniques do, although it ends up causing long-lasting, transmural lesions. Most importantly, it is relatively selective on cardiac myocytes and therefore potentially safer than thermal techniques. Some PFA systems can be combined with electroanatomic mapping systems. However, as of now, it appears that these ablation technologies should be considered complementary rather than alternative for a number of practical and theoretical reasons.

Keywords: atrial fibrillation ablation; cryoballoon ablation; pulsed field ablation; radiofrequency ablation.

Figure 1

Arctic Front^TM cryoballoon ablation catheter. Contrast injection in left inferior pulmonary vein.