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

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.

Atrial fibrillatory cycle length: computer simulation and potential clinical importance.

AIMS: Atrial fibrillatory cycle length (AFCL) is generally accepted as a surrogate marker for local refractoriness. In this study, a computer model and clinical data on human subjects undergoing catheter ablation for paroxysmal and persistent AF were used to determine the clinical potential of AFCL. METHODS AND RESULTS: Simulations were performed in a biophysical computer model of AF, induced from eight simultaneously active focal sources. Atrial fibrillatory cycle length persistence and termination were assessed in response to successively switching off the involvement of the eight sources. Electrophysiological data were obtained from 178 subjects undergoing catheter ablation of AF. Atrial fibrillatory cycle length, measured in the atria appendages using automated monitoring software, was studied to determine its clinical correlation, the complexity of the ablation procedure, and the AF termination success rate. Computer simulations showed an inverse relationship between the number of sources participating in AF maintenance and AFCL. Clinical data demonstrated a strong relationship between duration, degree of ablation, and AFCL, with shorter AFCL associated with more extensive ablation to terminate AF. Atrial fibrillatory cycle length was prolonged exponentially at each stage, with a critical cycle length of approximately 200 ms for AF conversion. CONCLUSION: Atrial fibrillatory cycle length is inversely associated with the number of sources participating in AF maintenance observed in the computer model. In addition, AFCL is an important predictor of baseline duration of the arrhythmia, type of AF, and ease of catheter ablation therapy to terminate AF.

Cycle length dependent block in the "mitral-pulmonary vein" isthmus.

We report a case of cycle length dependent activation sequence in the coronary sinus catheter during assessment of mitral-pulmonary vein isthmus block. A 61-year-old patient presented with atrial tachycardia following a recent pulmonary vein isolation for paroxysmal atrial fibrillation. A perimitral macroreentrant atrial tachycardia was demonstrated during mapping. The isthmus block observed following initial ablation of the mitral-pulmonary vein appeared to be pacing cycle dependent and to our knowledge has not been previously described.