Remote MAGNetic Catheter Ablation for Atrial Fibrillation

Background: Since the first description in 1998 catheter-interventional ablation (CA) has evolved to a standard treatment for symptomatic drug-refractory atrial fibrillation (AF).

Ablation efficacy but also complication percentage and radiation exposure are influenced by several factors, among them patient age, body weight, type and duration of AF, underling cardiac disease as well as the used ablation method, technology and the experience of the operator.

The objectives of developing a system for remote magnetic catheter navigation (RMN) were to improve the efficacy and safety of complex ablation procedures and to reduce radiation exposure. However, convincing data supporting this theory are still lacking.

Aim: To evaluate efficacy, safety profile / complication rate and radiation exposure in serial ablation procedures for paroxysmal and persistent AF as well as repeat interventions based on remote magnetic navigation and 3-D image integration with assessment of the learning curve for this complex technology.

Design: single center observational registry, analytical questioning, non-randomized, non-controlled, not blinded, consecutive patient inclusion

Study population:

Inclusion criteria

Consecutive patients with class I or class IIa indication for CA for symptomatic atrial fibrillation according to the current guidelines.

Exclusion criteria

• Contraindication for AF catheter ablation
• Contraindication for RMN procedure. (These patients may undergo AF ablation with another technology, e.g. cryo-balloon ablation).
• Age < 18 years, gravidity

Endpoints Primary endpoint

Safety:

• The number of peri-procedural major complications.
• Adverse events are classified according to the 2012 Expert consensus statement on catheter and surgical ablation of AF [Calkins H et al. 2012 HRS/EHRA/ECAS Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation. Europace (2012) 14, 528-606 doi:10.1093/europace/eus027].

Secondary endpoints Efficacy

• Acute: number of successfully isolated pulmonary veins.
• Mid-term: freedom from any atrial tachyarrhythmia (atrial fibrillation/atypical atrial flutter/atrial tachycardia; duration > 30 sec) after 6 months follow-up (initial blanking period of 3 months).
• Long-term:
• Freedom from any atrial tachyarrhythmia (duration > 30 sec) after 12 months follow-up (initial blanking period of 3 months).
• Time to first recurrence of an atrial tachyarrhythmia after an initial blanking period of 3 months.

Radiation exposure:

• mean effective dose (ED), based on the measured dose-area-product. Aim is to show the potential of RMN to reduce the mean ED below 1.5 mSv in daily routine RMN AF ablation procedures
• The fluoroscopy parameters are documented for system calibration (A), transseptal access/catheter positioning (B), mapping/ablation (C).

Safety:

• Number of peri-procedural minor complications
• Number of all procedure-related complications during 12 months follow-up.

Subgroups:

• Type of AF (paroxysmal versus non-paroxysmal)
• Type of antiarrhythmic drug treatment (AAD)
• Demonstration of low-voltage areas / fibrosis
• Ablation: only pulmonary vein antral isolation (PVAI) versus additional substrate modification / box isolation of fibrotic areas (BIFA)
• Adipositas (BMI ≥ 30 kg/m²)
• Transseptal access after puncture versus via patent foramen ovale
• First ablation versus repeat procedure

Randomisation: none

Study procedure:

Pre-ablation: screening of all patients, referred for catheter ablation for AF. Inclusion after given informed consent. Oral anticoagulation (OAC) for at least 3 weeks. Transesophageal echocardiography (TEE) in all patients.

Ablation: Non-interrupted OAC, non-vitamin-K antagonist treatment withheld only the morning before ablation. All patients undergo PVAI and mapping for fibrotic areas, additional substrate modification on decision of the operator.

Techniques and technologies used: RMN: Niobe/Epoch®, Navigant™, 0.1 Tesla, Stereotaxis Inc.; fluoroscopy system: Siemens AXIOM-Artis VC12B, 6-1 fps; non-fluoroscopic mapping (NFM): Carto-RMT, magnetic resonance-image-integration, (Biosense-Webster Inc.); TEE-guided single transseptal puncture, "Single catheter ablation" technique: Navistar-RMT Thermocool (Biosense-Webster Inc.), target temperature 48°C, power limit 40Watts (posterior left atrial wall) up to 50W, irrigation infusion rate 17 mL/min; Heparin for maintaining an activated clotting time between 300 to 400 sec. Endpoint: bidirectional PV-block.

Post-ablation in hospital: OAC continued immediately following sheath removal after ablation for a minimum of 2 months, thereafter according to embolic risk (CHA2DS2-VASc-risk evaluation). 48 hours telemonitoring, echocardiography.

Follow up: blanking period 3 months. Clinical evaluation after 3, 6 and 12 months including echocardiography and 72-hours Holter.

Unscheduled visits for complications and symptoms suggesting recurrent tachyarrhythmia.

Inclusion criteria

• Consecutive patients with class I or class IIa indication for catheter ablation for symptomatic atrial fibrillation according to the current guidelines.

Exclusion criteria

• Contraindication for AF catheter ablation
• Contraindication for magnetically guided ablation procedure
• Age < 18 years, gravidity, breast feeding