Dual energy for pulmonary vein isolation using dual-energy focal ablation technology integrated with a three-dimensional mapping system: SmartfIRE 3-month results

Abstract

Aims: Contact force (CF)-sensing radiofrequency (RF) catheters with an ablation index have shown reproducible outcomes for the treatment of atrial fibrillation (AF) in large multicentre studies. A dual-energy (DE) focal CF catheter to deliver RF and unipolar/biphasic pulsed field ablation (PFA), integrated with a three-dimensional (3D) mapping system, can provide operators with additional flexibility. The SmartfIRE study assessed the safety and efficacy of this novel technology for the treatment of drug-refractory, symptomatic paroxysmal AF. Results at 3 months post-ablation are presented here.

Methods and results: Pulmonary vein isolation (PVI) was performed using a DE focal, irrigated CF-sensing catheter with the recommendation of PFA at posterior/inferior and RF ablation at the anterior/ridge/carina segments. Irrespective of energy, a tag size of 3 mm; an inter-tag distance ≤6 mm; a target index of 550 for anterior, roof, ridge, and carina; and a target index of 400 for posterior and inferior were recommended. Cavotricuspid isthmus ablation was permitted in patients with documented typical atrial flutter. The primary effectiveness endpoint was acute procedural success. The primary safety endpoint was the rate of primary adverse events (PAEs) within 7 days of the procedure. A prespecified patient subset underwent oesophageal endoscopy (EE; 72 h post-procedure), neurological assessment (NA; pre-procedure and discharge), and cardiac computed tomography (CT)/magnetic resonance angiogram (MRA) imaging (pre-procedure and 3 months post-procedure) for additional safety evaluation, and a mandatory remapping procedure (Day 75 ± 15) for PVI durability assessment. Of 149 patients enrolled between February and June 2023, 140 had the study catheter inserted (safety analysis set) and 137 had ablation energy delivered (per-protocol analysis set). The median (Q1/Q3) total procedure and fluoroscopy times were 108.0 (91.0/126.0) and 4.2 (2.3/7.7) min (n = 137). The acute procedural success rate was 100%. First-pass isolation was achieved in 89.1% of patients and 96.8% of veins. Cavotricuspid isthmus ablations were successfully performed in 12 patients [pulsed field (PF) only: 6, RF only: 5, and RF/PF: 1]. The PAE rate was 4.4% [6/137 patients; 2 pulmonary vein (PV) stenoses, 2 cardiac tamponades/perforations, 1 stroke, and 1 pericarditis]. No coronary artery spasm was reported. No oesophageal lesion was seen in the EE subset (0/31, 0%). In the NA subset (n = 30), microemboli lesions were identified in 2 patients (2/30, 6.7%), both of which were resolved at follow-up; only 1 was symptomatic (silent cerebral lesion, 3.3%). In the CT/MRA subset (n = 30), severe PV narrowing (of >70%) was detected in 2 patients (2/30, 6.7%; vein level 2/128, 1.6%), of whom 1 underwent dilatation and stenting and 1 was asymptomatic; both were associated with high index values and a small inter-tag distance. In the PV durability subset (n = 30), 100/115 treated PVs (87%) were durably isolated and 18/30 patients (60.0%) had all PVs durably isolated.

Conclusion: A DE focal CF catheter with 3D mapping integration showed a 100% acute success rate with an acceptable safety profile in the treatment of paroxysmal AF. Prespecified 3-month remapping showed notable PVI durability.

Clinical trial registration: ClinicalTrials.gov Identifier: NCT05752487.

Keywords: Contact force catheter; Dual energy; Focal catheter; Pulmonary vein isolation; Pulsed field ablation; VISITAG SURPOINT.

Graphical Abstract

Figure 1

Study ablation workflow for PVI using the dual-energy (RF/PF) contact force catheter. LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; PF, pulsed field; PVI, pulmonary vein isolation; RF, radiofrequency; RIPV, right inferior pulmonary vein; RSPV, right superior pulmonary vein. Images are courtesy of © Biosense Webster, Inc. All rights reserved.

Figure 2

Patient disposition. CT, computed tomography; EE, oesophageal endoscopy; mITT, modified intent-to-treat; MRA, magnetic resonance angiogram; NA, neurological assessment; PV, pulmonary vein. ^aOne patient did not meet the age requirement (18–75 years of age). One patient had some medical problems, and the investigator decided not to include that patient.

Figure 3

Spatial distribution of reconnections at remapping in patients of PV durability subset. Distribution of reconnections seen in 12 out of 30 subset patients. The posterior carina of the right circle was involved in 9 out of 12 cases. LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; PA, posterior-anterior; PV, pulmonary vein; RIPV, right inferior pulmonary vein; RSPV, right superior pulmonary vein. Images are courtesy of © Biosense Webster, Inc. All rights reserved.

Figure 4

Example of index procedure with remap. Patient from the subset population in which reconnection of the RSPV was observed at the time of the mandatory repeat study. (A) Activation map during pacing at the ostium of the coronary sinus during remapping procedure. The reconnection of the RSPV was based on a small gap at the posterior carina of the right circle. (B) Ablation set from the index procedure. The contiguity of the circle suggests that non-transmurality of the PF application is the cause of reconnection at the carina. LAT, local activation time; PF, pulsed field; PFA, pulsed field ablation; RF, radiofrequency; RSPV, right superior pulmonary vein. Images are courtesy of © Biosense Webster, Inc. All rights reserved.