First Clinical Experience With Reversible Electroporation Mapping in Atrial Flutter

Reversible pulsed field ablation (PF_REV) can temporarily block cardiomyocyte conduction, potentially identifying critical target sites before creating definitive lesions. However, PF_REV local capture might interfere with the tachycardia mechanism. The aim of the study was to characterize the responses of nontriggered PF_REV pulses to serve as a novel clinical mapping tool in reentrant atrial flutter.

PF_REV pulses were delivered in and outside of the circuit using a 9-mm lattice-tip catheter in 30 reentrant atrial tachycardias in 26 patients. The presence of local capture and responses to PF_REV pulses was characterized.

Out of 163 PF_REV pulses analyzed, 56 (34.4%) showed atrial capture and propagation. Propagated versus Nonpropagated PF_REV cohorts were compared. The coupling interval of propagated PF_REV pulses was significantly longer (195.3±69.2 msec versus 98.9±77.2 msec; P<0.001). Globally, 4 responses were observed: tachycardia termination (11.0%), stable tachycardia cycle length (TCL) prolongation (9.8%), transient irregular TCL variations (3.1%), and no change in activation sequence and TCL (76.1%). Propagation was only associated with irregular TCL variations (8.9% versus 0%, P=0.002). Tachycardia termination or TCL prolongation occurred only when PF_REV was delivered in the reentry circuit (100% specificity). Termination occurred exclusively in the critical isthmus (100% specificity regardless of propagation), and stable TCL prolongation occurred in 93.8% and 6.2% of the cases in the isthmus and outer loop, respectively (100% specificity for nonpropagated and 83.3% specificity for propagated PF_REV to localize the isthmus). Sensitivity of termination or stable TCL prolongation for identifying the critical isthmus was moderate (38.8%) and influenced by isthmus width (11.7±1.7 mm versus 22.9±2.1 mm; P<0.001). Reproducibility of PF_REV pulses, determined by consecutive pulses delivered at the same site producing identical responses, was high (82.9%).

PF_REV mapping is a novel, feasible, and reproducible tool for identifying critical sites in reentrant atrial tachycardia with narrow isthmuses that may be improved through optimized triggering and dose titration.