Reversible electroporation in atrial flutter: a novel mapping tool

Reversible pulsed field ablation (PFREV) can temporarily disrupt cardiomyocyte conduction and may emerge as a novel mapping tool to accurately identify critical isthmuses in tachycardia circuits before creating permanent lesions.

We aimed to systematically describe the responses to PFREV delivery during tachycardia, assessing its performance as a mapping tool.

PFREV pulses were delivered using a 9-mm lattice-tip ablation catheter in 9 patients undergoing reentrant atrial flutter ablation, targeting sites both in and outside the circuit, defined by entrainment mapping and high density activation mapping. Only non-propagated PFREV pulses were analyzed in order to minimize the potential interference of a non-triggered atrial capture with the tachycardia. The responses to non-propagated PFREV pulses were classified as: (1) Tachycardia termination; (2) Stable tachycardia cycle length (TCL) prolongation of at least 10 msec lasting more than 30 seconds; and (3) Absence of change in tachycardia activation sequence or TCL.

Forty-eight non-propagated PFREV pulses were delivered to 9 tachycardia circuits (3 CTI-dependent flutters, 2 perimitral flutters, two scar-related atrial flutters and two microreentry flutters). The three responses were observed: termination (12.5%), TCL prolongation (12.5%), and no effect (75%). Thirty-one (65%) PFREV pulses were delivered within the circuit (21 at isthmus and 10 at outer-loop sites) and 17 PFREV pulses were delivered outside the circuit. Of those delivered at the isthmus, 6 (28.6%) led to termination, 6 (28.6%) to TCL prolongation, and the remaining 9 (42.8%) had no effect. None of the 10 and 17 PFREV pulses delivered at the outer-loop and outside the circuit, respectively, induced any change. The isthmus was significantly wider when no PFREV effect was observed, compared to those at which prolongation and/or termination occurred (28mm, IQR 26.5-28mm vs. 10mm, IQR 8.5-10.8mm; p=0.037). Nineteen non-propagated PFREV pulses were repeatedly delivered at the same site: 84.2% elicited the same type of response, increasing to 94.7% when both termination and TCL prolongation were combined.

PFREV mapping of reentrant atrial tachycardia is feasible, with termination and TCL prolongation reproducibly identifying critical isthmus of reentrant tachycardias with 100% specificity. The sensitivity of both termination and TCL prolongation was reasonable (28.6% respectively, 57.2% when combined), probably influenced by anatomical characteristics of the isthmus.

PFREV responses and reproducibility