Dual-energy lattice-tip ablation system for persistent atrial fibrillation: a randomized trial

Abstract

Clinical outcomes of catheter ablation for atrial fibrillation (AF) are suboptimal due, in part, to challenges in achieving durable lesions. Although focal point-by-point ablation allows for the creation of any required lesion set, this strategy necessitates the generation of contiguous lesions without gaps. A large-tip catheter, capable of creating wide-footprint ablation lesions, may increase ablation effectiveness and efficiency. In a randomized, single-blind, non-inferiority trial, 420 patients with persistent AF underwent ablation using a large-tip catheter with dual pulsed field and radiofrequency energies versus ablation using a conventional radiofrequency ablation system. The primary composite effectiveness endpoint was evaluated through 1 year and included freedom from acute procedural failure and repeat ablation at any time, plus arrhythmia recurrence, drug initiation or escalation or cardioversion after a 3-month blanking period. The primary safety endpoint was freedom from a composite of serious procedure-related or device-related adverse events. The primary effectiveness endpoint was observed for 73.8% and 65.8% of patients in the investigational and control arms, respectively (P < 0.0001 for non-inferiority). Major procedural or device-related complications occurred in three patients in the investigational arm and in two patients in the control arm (P < 0.0001 for non-inferiority). In a secondary analysis, procedural times were shorter in the investigational arm as compared to the control arm (P < 0.0001). These results demonstrate non-inferior safety and effectiveness of the dual-energy catheter for the treatment of persistent AF. Future large-scale studies are needed to gather real-world evidence on the impact of the focal dual-energy lattice catheter on the broader population of patients with AF. ClinicalTrials.gov identifier: NCT05120193 .

Fig. 1. Participant flow diagram.

Of the 432 patients randomized to either treatment, 219 were assigned to undergo treatment with the investigational system and 213 were assigned to undergo treatment with the control system. Before the ablation procedure, seven patients in the investigational arm and five patients in the control arm were withdrawn. The primary analysis consisted of 212 patients in the investigational arm and 208 patients in the control arm. Of these 420 patients, 408 (97.1%) completed the trial with 12 months of follow-up.

Fig. 2. Primary and secondary effectiveness outcomes.

a, Kaplan–Meier analysis of the primary effectiveness endpoint. Shown are the Kaplan–Meier estimates of freedom from the primary effectiveness endpoint, which is a composite of the freedom from initial procedural failure, repeat ablation at any time and arrhythmia recurrence, anti-arrhythmic drug initiation or escalation or cardioversion after a 3-month blanking period. Comparison of the investigational arm versus control was performed using the two-sided log-rank test. b, Farrington–Manning analysis of the primary effectiveness endpoint. Trial success with respect to effectiveness was defined as non-inferiority of the primary effectiveness endpoint based on binomial proportions using the one-sided Farrington–Manning test with a non-inferiority margin of 15% and a one-sided alpha of 0.025. The observed difference in primary effectiveness success was 8.0% in favor of the investigational arm (95% two-sided CI: −0.9% to 16.8%), based on primary effectiveness for 210 investigational and 202 control patients. Visualized here is the pre-specified 15% non-inferiority margin, the point estimate of the difference between treatment and control and the two-sided 95% CI of the difference. c, Procedural characteristics. Left, energy application time includes both radiofrequency and PFA for the investigational device and radiofrequency time for the control device. Visualized here is the mean and 95% CI for the investigational arm (7.1 (6.8, 7.4), n = 212) and the control arm (36.4 (33.9, 38.8), n = 206) (P < 0.0001). Middle, transpired ablation time is the time between the first and last application, which includes the elapsed time for both PVI and any additional linear ablation. Visualized here is the mean and 95% CI for the investigational arm (46.7 (44.0, 49.4), n = 212) and the control arm (73.5 (68.8, 78.2), n = 208) (P < 0.0001). Right, skin-to-skin procedure time is the time elapsed from first venous access to last sheath removal. Visualized here is the mean and 95% CI for the investigational arm (100.9 (96.8, 105.1), n = 212) and the control arm (126.1 (119.4, 132.8), n = 208) (P < 0.0001). Contingent upon trial success, sequential testing with an overall one-sided alpha of 0.025 was performed on a pre-specified set of endpoints to further examine superiority of the investigational arm versus control. Adjustments were made for multiple comparisons with the sequential testing method.

Extended Data Fig. 1. Comparison of catheter ablation systems in the SPHERE Per-AF clinical trial.

The investigational Sphere-9TM lattice-tip dual energy catheter with AfferaTM Mapping and Ablation System is shown in the left panel. This system utilizes the Sphere-9TM catheter for both electroanatomical mapping and ablation, employing radiofrequency (red circles) or pulsed field (green circles) energies to create a line of electrical isolation around the pulmonary veins. The control system, depicted in the right panel, consists of a multielectrode mapping catheter for electroanatomical mapping and a separate catheter for radiofrequency ablation (THERMOCOOL® SMARTTOUCH® Surround Flow). As shown in the inserts, the investigational Sphere-9TM catheter has a wider footprint capable for creating wider lesions, resulting in a more contiguous ablation line. LIPV=left inferior pulmonary vein. LSPV=left superior pulmonary vein.