María Cespón-Fernández, Kazutaka Nakasone, Luigi Alfonso Pannone, Juan Sieira, Domenico G. Della Rocca, Alexandre Almorad, Ingrid Overeinder, Gezim Bala, Erwin Ströker, Ivan Eltsov, Anna Padisák, Giampaolo Vetta, P. Brugada, Gian-Battista Chierchia, Carlo de Asmundis, Andrea Sarkozy
BACKGROUND: 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. METHODS: 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. RESULTS: 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%). CONCLUSIONS: 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.