Pulsed Field Ablation of Atrial Fibrillation: A Novel Technology for Safer and Faster Ablation

Abstract

Atrial fibrillation (AF), the most common arrhythmia, is associated with increased morbidity, mortality, and healthcare costs. Evidence indicates that rhythm control offers superior cardiovascular outcomes compared to rate control, especially when initiated early after the diagnosis of AF. Catheter ablation remains the single best therapy for AF; however, it is not free from severe complications and only a small percentage of AF patients in the Western world ultimately receive ablation. Ensuring that AF ablation is safe, effective, and efficient is essential to make it accessible to all patients. With the limitations of traditional thermal ablative energies, pulsed field ablation (PFA) has emerged as a novel non-thermal energy source. PFA targets irreversible electroporation of cardiomyocytes to achieve cell death without damaging adjacent structures. Through its capability to create rapid, selective lesions in myocytes, PFA presents a promising alternative, offering enhanced safety, reduced procedural times, and comparable, if not superior, efficacy to thermal energies. The surge of new evidence makes it challenging to stay updated and understand the possibilities and challenges of PFA. This review aims to summarize the most significant advantages of PFA and how this has translated to the clinical arena, where four different catheters have received CE-market approval for AF ablation. Further research is needed to explore whether adding new ablation targets, previously avoided due to risks associated with thermal energies, to pulmonary vein isolation can improve the efficacy of AF ablation. It also remains to see whether a class effect exists or if different PFA technologies can yield distinct clinical outcomes given that the optimization of PFA parameters has largely been empirical.

Keywords: atrial fibrillation; catheter ablation; electroporation; pulsed field ablation.

Figure 1

Biophysics of pulsed field ablation. (a) The plasma membrane, a bilayer lipid membrane, acts as a capacitor by separating electrical charges (inside: −60 to −70 mV relative to the outside; resting membrane potential). Exposure to an external electric field induces additional charges, creating an induced transmembrane voltage that combines with the resting potential. This voltage facilitates water molecule penetration and phospholipid reorientation, forming aqueous pores. (b) Pulsed field generators use direct current power supplies to charge capacitors, which discharge pulses between two electrodes, creating an electric field. Pulses are biphasic, square-shaped, and delivered in bursts. (c) Cellular response to the electric field primarily depends on electric field strength and pulse duration.

Figure 2

Tissue selectivity of pulsed field ablation (PFA). (a) PFA selectively targets atrial myocardium while sparring adjacent structures, contrasting with thermal energy-based methods. (b) Electroporation allows for the titration of electric field strength to tissue-specific thresholds, inducing selective cell death. Section (b) has been adapted with permission from Elsevier, ref. [38].

Figure 3

Purported advantages of pulsed field ablation (PFA). PFA’s tissue selectivity has been shown to minimize damage to adjacent structures, thereby reducing energy-specific risks associated with atrial fibrillation (AF) catheter ablation. From a technical perspective, PFA does not significantly increase tissue temperature, eliminating the risk of charring and pops, a characteristic that may enhance procedural safety. Additionally, PFA creates uniform lesions, regardless of the presence of scar tissue, and demonstrates less dependence on contact force. Clinical trials with a dual-arm design comparing PFA with thermal ablation have demonstrated that PFA is safer and reduces overall procedural times. It remains speculative whether future refinements in PFA delivery will improve the efficacy of AF ablation.

Figure 4

Catheters capable of pulsed field ablation that have received CE market approval. Comparison of different characteristics associated with each catheter.

Figure 5

Affera™ (Medtronic Inc., MN, USA) 3D mapping system. (a) Pre-ablation voltage map of the left atrium. (b) Post-ablation voltage map of the left atrium. Green circles indicate the focal footprint of the Sphere-9™ catheter used for pulsed field ablation. The patient underwent wide-circumferential antral ablation and posterior box isolation with both superior and inferior lines. Source: routine ablation performed at our center outside an investigational context when the Sphere-9 catheter had already received CE market approval.

Figure 6

Varipulse™ integrated into the CARTO3™ (Biosense Webster, Irvine, CA, USA) mapping system. (a,b) The Varipulse™ catheter is moved to create electroanatomical map of the left atrium. The catheter delivers pulsed field ablations (PFA) at precise locations through accurate visualization. The tissue proximity indicator (electrodes bordered in thicker white lines in (a)) is used to evaluate the contact with the endocardium. Pulsed field tag coloring provides information of the ablation; inter-tag connectors reveal lesion contiguity between electrodes (c). Left atrial final voltage map acquired after PFA (b). Source: image provided by Biosense Webster.