Disclosures:
Dr Romero has received grant support from Biosense Webster (BWI-IIS-535)
for an investigator-initiated study (The PLEA Trial;
https://www.clinicaltrials.gov; Unique identifier: NCT04216667). Dr.
Romero is a paid consultant for Biosense Webster, Sanofi-Aventis and
AtriCure.
Funding: None
Catheter ablation (CA) is the mainstay therapy for the maintenance of
sinus rhythm in patients with paroxysmal and persistent atrial
fibrillation (AF). Pulmonary vein isolation (PVI) has remained the most
frequently used treatment strategy for this entity. Radiofrequency
ablation (RFA), which has been in use for over 3 decades, is the most
frequent energy source implemented for CA followed by cryoablation and
laser, with alternative energy sources (including focused ultrasound,
and microwave energy) used mainly in investigational studies with
limited clinical applicability. The understanding of RF biophysics
enables electrophysiologists to titrate tissue current delivery to
control lesion surface area and depth. Nonetheless, in the case of PVI,
RFA is associated with several potential complications or significant
adverse events, including pulmonary vein stenosis, incomplete
circumferential ablation, and thermal damage to adjacent structures
(e.g., right phrenic nerve, esophagus), which limits lesion efficacy to
maintain patient safety.
Although cryoablation was introduced as a faster and potentially safer
alternative to achieve a complete PVI, it was also associated with a
significant risk of phrenic nerve and esophageal injury and offers no
real advantages in terms of arrhythmia recurrence (1). Use of direct
current (DC) delivered through diagnostic catheters to elicit cellular
destruction dates to the early days of CA. Nonetheless, the large amount
of energy necessary to produce tissue destruction (up to 300 J - by what
was considered to be “fulguration”) was painful and the delivery of
large monophasic unipolar defibrillation waveforms from small surface
area diagnostic electrodes resulted in hazardous effects (2-4). These
included the formation of gas vapor globe and arcing at the tip of the
electrode, which produced barotrauma related complications including
myocardial perforation and tamponade and formation of non-homogeneous
lesions, which were proarrhythmic (5,6). The mechanism of lesion
formation during DC ablation was later determined to be irreversible
electroporation (IRE) (7,8). Subsequent studies used lower energy to
achieve successful ablation with a reduced risk of adverse events
(9-11). Nevertheless, before these improvements could be adopted, RFA
became available and quickly achieved widespread acceptance given the
ability to provide a controlled amount of energy, a greater
effectiveness and a lower incidence of life-threatening complications
compared to DC ablation.
Recently, ablation using electric fields generated by short pulses of
high energy, known as pulsed field ablation (PFA), has shown promise by
specifically targeting myocardium without generating heat or damaging
adjacent tissue.