Elsevier

Heart Rhythm

Volume 7, Issue 8, August 2010, Pages 1029-1035
Heart Rhythm

Clinical
Ablation
Endo-epicardial ablation of ventricular arrhythmias in the left ventricle with the Remote Magnetic Navigation System and the 3.5-mm open irrigated magnetic catheter: Results from a large single-center case–control series

https://doi.org/10.1016/j.hrthm.2010.04.036Get rights and content

Background

Remote magnetic navigation (RMN) has been reported as a feasible and safe mapping and ablation system for treatment of ventricular arrhythmias (VAs). However, the reported success rates have been limited with the 4- and 8-mm catheter tips.

Objective

This study sought to report the results in a large series of consecutive patients undergoing radiofrequency (RF) catheter ablation of VAs using the RMN with the 3.5-mm magnetic open-irrigated-tip catheter (OIC).

Methods

A total of 110 consecutive patients with a clinical history of left VA were included in the study. In all cases, an OIC was utilized for mapping and ablation. When ablation with the RMN catheters failed, a manual OIC was used to eliminate the VA. Postablation pacing maneuvers and isoproterenol were used to verify the inducibility of the VAs. Outcomes were compared with those of a group of 92 consecutive patients undergoing manual ablation by the same operator.

Results

Mapping and ablation with the magnetic OIC were performed in all 110 patients with VA. Ischemic cardiomyopathy was present in 33 (30%), nonischemic in 14 (13%), and in 63 (57%) patients no structural heart disease was present. Endocardial mapping was performed in all patients, whereas both endocardial and epicardial mapping were performed in 36 (33%) patients. Compared with manual ablation, RMN was associated with a longer procedural time (2.9 ± 1.2 hours vs. 3.3 ± 1.1 hours, P = 0.004) and RF time (24 ± 12 minutes vs. 33 ± 18 minutes, P = 0.005), whereas fluoroscopic time was significantly shorter (35 ± 22 minutes vs. 26 ± 14 minutes, P = 0.033). During the procedures, crossover to manual ablation was required in 15 patients (14%). At 11.7 ± 2.1 months of follow-up in the study group and 18.7 ± 3.7 months in the manual ablation group, 85% and 86% (P = 0.817) of patients, respectively, were free of VA.

Conclusion

This large series of consecutive patients demonstrates that OIC ablation using RMN is effective for the treatment of left VAs.

Introduction

Radiofrequency catheter ablation (RFCA) is an important option for controlling recurrent ventricular arrhythmias (VAs).1, 2, 3 The field has evolved rapidly due to introduction of new technologies, improved understanding of arrhythmia mechanisms, and improved procedural safety and patient outcomes. However, results are often operator dependent and difficult to replicate. Remote magnetic navigation (RMN) and ablation is a new technology that offers the possibility to reduce the operator dependency and improve catheter stability while minimizing the physician's exposure to radiation. Clinical studies have consistently reported that RMN may represent a new and safe strategy to successfully ablate both supraventricular and ventricular arrhythmias.4, 5, 6, 7, 8, 9, 10

To date, the major drawback of RMN is the unavailability of a magnetic open-irrigated-tip catheter (OIC), thus limiting RF power to be maintained in a desirable range in areas of low local blood flow, such as dilated and poorly contracting ventricles.11, 12, 13 For this reason, operators may frequently need to switch to manual ablation to improve the transmurality and efficacy of the lesions. This represents a significant limitation for ablation of VAs, especially in the presence of a structural heart disease, because of the relatively larger size of responsible re-entrant circuits and the fact that they can be located deep to the endocardium. Accordingly, ablation through nonirrigated catheters in this clinical setting often fails to achieve adequate ablation of lesions.14, 15

The purpose of this study was to evaluate the safety and efficacy of RFCA using the RMN system with the magnetic OIC ablation catheter in a large series of patients with VAs.

Section snippets

Methods

One hundred and ten consecutive patients with clinical and symptomatic VAs underwent RFCA with the remote magnetic navigation (Stereotaxis, St. Louis, Missouri) and the magnetic OIC between March 2009 and November 2009.

The 7-F 3.5-mm-tip floppy irrigated catheter (Navistar Thermocool RMT, Biosense Webster, Diamond Bar, California) became available in the United States in March 2009 to overcome the limitations of the previous 4-mm and 8-mm nonirrigated magnetic catheter. All Remote Magnetic

Patient characteristics

The clinical characteristics and electrophysiologic features of the 110 patients undergoing RFCA with the RMN system are reported in Table 1. The mean LV ejection fraction was 40% ± 14%. All patients included in this study had previously failed treatment with 2 ± 0.9 antiarrhythmic drugs (AADs). Twenty-six (24%) patients presented with the clinical morphology of sustained VT, and 84 (76%) patients had frequent PVCs. Forty-five (41%) patients had an implantable cardioverter-defibrillator (ICD)

Major findings

This is the largest series of consecutive patients undergoing catheter ablation of VAs and PVCs with LV origin using the robotic magnetic navigation system with the new magnetic ablation OICs. The use of the system seems to be feasible, safe, and efficacious for the treatment of VAs in a wide variety of conditions such as normal structural heart or cardiomyopathy with low ejection fraction. In this series, the follow-up was extended to 1 year and clinical success was 85%.

The study population

Conclusion

This large series of consecutive patients shows that catheter ablation of LV arrhythmias with a magnetic OIC and RMN system is effective.

References (22)

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    Mapping and ablation of ventricular arrhythmias with magnetic navigation: comparison between 4- and 8-mm catheter tips

    J Interv Card Electrophysiol

    (2009)
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