Feasibility and outcomes of catheter ablation using robotic magnetic navigation in patients with congenital heart disease with varying defect complexity

Abstract

Introduction

Robotic magnetic navigation (RMN) allows for catheter ablation in the presence of complex cardiac anatomy, such as that seen in congenital heart disease (CHD). The objective of this study was to evaluate the feasibility, efficacy and safety of this procedure in a wide range of CHD conditions.

Methods

Patients with CHD who underwent catheter ablation for cardiac arrhythmias using RMN were included in this single-centre observational study. Patients’ baseline characteristics, procedural data, periprocedural complications and acute success rates were obtained. The efficacy of the ablation was evaluated during follow-up in the outpatient clinic using 24-h Holter monitoring.

Results

The study population consisted of 38 patients (26 males) with a median age of 36.8 (IQR 30.8-39.6) years. Surgically corrected transposition of the great arteries was the most common CHD, observed in 14 patients (36.8%). Nineteen patients (50.0%) had more than one congenital defect. Intra-atrial re-entrant tachycardia was the most common arrhythmia ablated, accounting for 21 procedures (55.3%).

Median procedural time was 232.5 min (IQR 186.3-281.3); the median radiation dose and radiation time were 2.4 mGy m² (IQR 1.3-4.4) and 14.0 min (IQR 9.5-30.4), respectively. Acute arrhythmia cessation was observed in 81.6% of procedures. Major complications were noted in 2 cases (5.3%). The median time from the ablation to follow-up was 5.4 months (IQR 3.4-9.3). Arrhythmia recurrence was observed in 7 cases (18.4%).

Conclusions

RMN is a valuable tool for catheter ablation of arrhythmias in patients with congenital heart disease and complex anatomy.

Graphical abstract

Highlights

• •Ablation using RMN in CHD patients appears safe and feasible for many arrhythmias.
• •Post-Mustard/Senning ablation using RMN avoided transbaffle puncture.
• •Catheter ablation using RMN was safely performed in patients with CHD anatomy.

1. Introduction

Cardiac arrhythmias are one of the most common causes of morbidity and mortality in adults with congenital heart disease (CHD) [1]. Radiofrequency (RF) catheter ablation is commonly used for the treatment of cardiac arrhythmias [2]. Understanding congenital anatomy and reviewing the details of prior cardiac surgery are essential for obtaining proper access during the ablation procedure. Nevertheless, reaching the arrhythmia substrate area and performing consistent lesions with the ablation catheter can be challenging [3,4].

Robotic magnetic navigation (RMN) systems allow catheter ablation to be manoeuvred with the use of a magnetic field and remote control [5]. They provide less exposure to X-ray radiation and decrease the risk of tissue perforation, although they may extend the procedure time compared to manual methods [6]. RMN constitutes a valuable tool to achieve access to specific arrhythmia substrate sites in patients with CHD, especially those who have undergone reparative surgery for the most complex defects, in whom conventional manually steered catheters may be unable to reach the target sites reliably [7]. The flexibility of the RMN catheter may be particularly advantageous in patients with tortuous vascular pathways, conduits, and baffles, including Mustard or Senning operations for dextro-transposition of the great arteries (d-TGA).

1.1. Aim

The aim of this study was to evaluate the efficacy, feasibility, and safety of catheter ablation in patients with CHD using the new Genesis RMN system (Stereotaxis, St. Louis, Missouri, USA).

1.2. Study oversight and support

This research received no commercial support for its conduct or the preparation of this report. In accordance with Polish law, it was determined that ethics committee approval was not required.

2. Methods

All consecutive patients with CHD who underwent catheter RF ablation for cardiac arrhythmias using RMN were included from April 2022 to September 2024. Anti-arrhythmic drugs were discontinued at least five half-lives prior to the procedure. Procedures were performed using the Genesis Robotic Magnetic Navigation System (Stereotaxis, St. Louis, Missouri, USA) and a magnetic-guided 8 Fr RF ablation catheter (THERMOCOOL® RMT Catheter, Biosense Webster, Irvine, CA, USA).

Indications for RMN included a difficult-to-access arrhythmogenic substrate site using manual techniques or suspected difficulties in maintaining catheter stability during RF energy delivery. A CT scan and echocardiography were performed prior to ablation to visualise cardiac anatomy and function. CHD was classified as mild, moderate, or severe according to a consensus statement to reflect the complexity of the disease [8].

Patients’ baseline characteristics, procedural data, such as procedure duration, radiation dose, type of vascular access, radiofrequency application parameters, and periprocedural complications were obtained. The efficacy of the ablation was evaluated during follow-up in the outpatient clinic with the use of 24-h Holter monitoring. Ablation efficacy was assessed during outpatient follow-up through clinical evaluation and rhythm monitoring. Follow-up included patient interviews regarding recurrent arrhythmia symptoms and review of any out-of-hospital electrocardiographic (ECG) recordings, together with at least one objective rhythm assessment performed ≥3 months after the procedure, including 12-lead ECG, 24-h Holter monitoring, or interrogation of an implantable cardiac device, when applicable. Acute procedural success was defined as arrhythmia termination and non-inducibility at the end of the procedure. Long-term success was defined as freedom from documented recurrence of the clinical arrhythmia, with recurrence defined as at least one episode of sustained clinical arrhythmia documented during follow-up.

2.1. Statistical analyses

Categorical data were presented as counts and percentages. Continuous variables were reported as medians and interquartile ranges (IQR – Q1 to Q3) for non-normally distributed data, or as means and standard deviations (SD) for normally distributed data. Patients were categorized by CHD complexity (simple, moderate, or complex). Exploratory pairwise comparisons between complexity groups were performed using Fisher's exact test for categorical variables, Welch's two-sample t-test for normally distributed continuous variables, and the Mann–Whitney U test for non-normally distributed continuous variables.

The analysis involved pairwise comparisons between the three categories. No adjustment was made for multiple comparisons. Statistical analysis was performed using R version 4.1.2 and RStudio software. A p-value <0.05 was considered statistically significant.

3. Results

The study group comprised 35 patients, undergoing a total of 38 catheter ablation procedures (26 in males), with a median patient age of 36.8 years (IQR 30.8–39.6). Dextro-transposition of the great arteries (d-TGA) was the most common CHD in the study population – 11 patients after Mustard or Senning procedures, 1 after a Rastelli procedure, and 1 after a Blalock–Hanlon procedure. Moreover, 19 patients (50.0%) had more than one congenital defect (Fig. 1).

Fig. 1.

A. Congenital heart diseases in described population. B. History of CHD correction. Abbreviations: ASD – Atrial septal defect; AVSD – atrioventricular septal defect; BAV – Bicuspid aortic valve; CoA – Coarctation of aorta; PDA – Patent ductus arteriosus; TGA – Transposition of great arteries; VSD – Ventricular septal defect.

Two patients (5.3%) had concomitant dilated cardiomyopathy. Heart failure was diagnosed in 25 patients (65.8%), with NYHA class I in most cases, 14 (36.8%), class II in 8 (21%), and class III in 3 (5.3%). Two patients had undergone tricuspid valve replacement.

Intra-atrial re-entrant tachycardia (IART), defined as a regular atrial arrhythmia with a confirmed macro-re-entry circuit during the procedure, was the most common arrhythmia – accounting for 27 procedures (71.1%) (Supplementary Material, Fig. S1). One patient underwent two ablations of an accessory pathway, and another underwent three IART ablation procedures.

Median procedural time was 232.5 min (IQR 186.3-281.3). The median radiation dose and radiation time were 2.4 mGy m² (IQR 1.3–4.4) and 14.0 min (IQR 9.5–30.4), respectively.

Periprocedural data are presented in Table 1.

Table 1.

Baseline patients’ characteristics, types of ablated arrhythmias, procedural/periprocedural data and follow-up according to CHD complexity. *-Simple-moderate,**- simple-severe, and ***-moderate-severe p-values.

Characteristic	Total (n = 38)	Simple (n = 7)	Moderate (n = 21)	Severe (n = 10)	P-value
Baseline characteristics
Male sex	26 (68.4%)	4 (57.1%)	15 (71.4%)	7 (70.0%)	0.647*
					0.644**
					1.000***
Age [years]	36.8 (30.8-39.6)	37.7 (37.1-44.2)	37.0 (32.1-41.9)	28.6 (19.9-33.9)	0.499*
					0.005**
					0.006***
Heart failure	25 (65.8%)	5 (71.4%)	15 (71.4%)	5 (50.0%)	1.000*
					0.622**
					0.423***
Cardiac pacemaker	7 (18.4%)	1 (14.3%)	5 (23.8%)	1 (10.0%)	1.000*
					1.000**
					0.634***
CRT-D	2 (5.3%)	1 (14.3%)	1 (4.8%)	0 (0.0%)	0.444*
					0.412**
					1.000***
Beta-blocker	32 (84.2%)	6 (85.7%)	16 (76.2%)	10 (100.0%)	1.000*
					0.412**
					0.147***
Anti-arrhythmic drug	10 (26.3%)	2 (28.6%)	3 (14.3%)	5 (50.0%)	0.574*
					0.622**
					0.074***
Right systemic ventricle	12 (31.6%)	1 (14.3%)	9 (42.9%)	2 (20.0%)	0.364*
					1.000**
					0.262***
Common systemic ventricle	4 (10.5%)	0 (0.0%)	0 (0.0%)	4 (40.0%)	1.000*
					0.103**
					0.007***
Severely reduced contractility of the systemic ventricle	3 (7.9%)	1 (14.3%)	1 (4.8%)	1 (10.0%)	0.444*
					1.000**
					1.000***
Atrial fibrillation	2 (5.3%)	0 (0.0%)	2 (9.5%)	0 (0.0%)	1.000*
					1.000**
					1.000***
Intra-atrial re-entrant tachycardia	27 (71.1%)	4 (57.1%)	17 (81.0%)	6 (60.0%)	0.318*
					1.000**
					0.381***
Focal atrial tachycardia	1 (2.6%)	1 (14.3%)	1 (4.8%)	0 (0.0%)	0.444*
					0.412**
					1.000***
Atrioventricular nodal re-entrant tachycardia	1 (2.6%)	0 (0.0%)	0 (0.0%)	1 (10.0%)	1.000*
					1.000**
					0.323***
Accessory pathway	5 (13.2%)	0 (0.0%)	2 (9.5%)	3 (30.0%)	1.000*
					0.228**
					0.296***
Ventricular ectopic beats	3 (7.9%)	3 (42.9%)	0 (0.0%)	0 (0.0%)	0.011*
					0.051**
					1.000***
Procedural outcomes
Procedural time [min] (IQR)	232.5 (186.3-281.3)	175.0 (157.5-225.0)	225.0 (186.3-281.3)	270.0 (235.0-285.0)	0.183*
					0.023**
					0.135***
Radiation dose [mGym2] (IQR)	2.4 (1.3-4.4)	2.1 (1.4-2.6)	2.3 (1.3-3.9)	3.4 (1.5-6.0)	0.698*
					0.329**
					0.322***
Periprocedural major complications	2 (5.3%)	0 (0.0%)	2 (9.5%)	0 (0.0%)	1.000*
					1.000**
					1.000***
Femoral vein access	34 (89.5%)	7 (100.0%)	19 (90.5%)	8 (80.0%)	1.000*
					0.485**
					0.577***
Femoral artery access	17 (44.7%)	0 (0.0%)	10 (47.6%)	7 (70.0%)	0.030*
					0.010**
					0.280***
RF time [min] (IQR)	16.1 (10.4-21.9)	16.4 (8.6-16.7)	16.6 (12.7-25.7)	12.7 (5.4-17.2)	0.222*
					0.740**
					0.263***
Follow-up outcomes
Clinical arrhythmia cessation during procedure	31 (81.6%)	5 (71.4%)	19 (90.5%)	7 (70.0%)	0.253*
					1.000**
					0.296***
Arrhythmia-free during follow-up	31 (81.6%)	3 (42.9%)	20 (95.2%)	8 (80.0%)	0.008*
					0.162**
					0.237***

Clinical acute arrhythmia cessation was observed after 31 procedures (81.6%). The distribution of arrhythmia recurrence over the years of the study period was comparable (Supplementary Material, Fig. S2). Periprocedural complications were noted in 2 cases (5.3%) – pericardial effusion in one patient, treated conservatively, and pharyngeal bleeding following periprocedural transoesophageal echocardiography (TEE) in another.

Follow-up data were obtained for 36 procedures. The median time from ablation to follow-up was 5.4 months (IQR 3.4–9.3). Arrhythmia recurrence was observed in 7 cases (18.4%). Partial success, defined as a significant reduction in clinical arrhythmia without complete resolution, was achieved in one patient, who had corrected d-TGA using a Mustard procedure.

In the most common CHD correction in our cohort, Mustard/Senning for d-TGA, all patients had IART. Arrhythmogenic substrate localisation was achieved using a transaortic approach in 10 patients, while the remaining patient with mechanical valve in tricuspid position underwent a standard transbaffle puncture approach under transoesophageal echocardiographic guidance [9].

Except for one patient with partial success at follow-up, no recurrences were observed. One patient with a double-outlet left ventricle and an implanted pulmonary homograft, who underwent atrial tachycardia ablation, died nine months after the procedure due to an unknown cause.

4. Discussion

Arrhythmias can have potentially fatal consequences in patients with congenital heart disease, as they often arise as part of the natural progression of the condition. In such patients, catheter ablation is indicated or should be considered [10]. In conventional manual procedures, anatomical access challenges may complicate this process and lead to delays in performing the ablation especially in patients after Mustard or Senning procedures for d-TGA. To our knowledge, this study represents the largest cohort of patients with CHD to undergo ablation using the new Genesis RMN system, which is more compact and faster than previous RMN systems.

Our analysis identified several significant findings.

• 1.Ablation for arrhythmias in patients with CHD using the Genesis RMN system was safe and feasible.
• 2.The use of RMN for catheter ablation in patients after Mustard or Senning correction allowed avoidance of the transbaffle puncture approach and the associated risk of residual leakage, with a very good procedural success rate, which confirms previous reports [11].

The observed ablation efficacy of approximately 80% in this selected cohort of CHD patients with difficult-to-access arrhythmogenic substrates or anticipated catheter instability underscores the value of RMN for managing complex arrhythmias in CHD [12]. Moderate CHD was the most common severity observed in the population studied. Right ventricular dysfunction was commonly observed on echocardiography while heart failure, although frequent in these patients, was mildly symptomatic (NYHA class I) in the majority of cases.

CHD makes catheter ablation challenging, but previous studies evaluating efficacy of manual ablation [[13], [14], [15]], in light of our results, suggest that RMN provides a promising method for arrhythmia treatment in hearts with congenital defects. Whereas conventional manual ablation often necessitates baffle puncture to access the pulmonary venous atrium, RMN may obviate the need for baffle puncture, thereby avoiding the risks of residual baffle leaks, hemodynamically significant shunting, and paradoxical embolism [16].

The two patients who experienced complications did not require additional procedures. One with throat hematoma was related to TEE and is not directly related with the RMN system used in this group of patients. In one case, the throat hematoma was related to TEE and was not directly associated with the RMN system used in this group of patients.

Akca et al. [17] previously described their results of ablation in the group of patients with CHD using the Niobe Magnetic Navigation System (Stereotaxis Inc., St. Louis, MO, USA). We obtained a longer procedural time, which may have been due to additional patient preparation time included in the overall procedure duration, whereas the total fluoroscopy time was shorter than in those studies.

A recently published meta-analysis about RMN in congenital heart diseases reported freedom from arrhythmia recurrence of 84.5% during a mean follow-up of 24.3 months, with the procedural complication rate of 3.5%, not attributable to RMN technology [18]. Another report revealed no significant difference in outcomes of RMN-guided ablation between acquired and congenital heart disease population [19].

The limitations of this study include the small sample size, which limits the statistical power of the results, the single-centre design, absence of a comparator group without CHD, and the relatively short follow-up period.

5. Conclusion

RMN is a valuable tool for catheter ablation of arrhythmias in patients with congenital heart disease and complex anatomy. Further studies with larger cohort size and greater number of events are needed to assess procedural efficacy and safety, especially for subgroup comparisons in a heterogenous CHD population.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author (JM).

Sources of funding

Manuscript preparation was supported during Harvard Medical School's Polish Clinical Scholars Research Training Program, organized by the Agencja Badan Medycznych (ABM, English: Medical Research Agency, Warsaw, Poland).

CRediT authorship contribution statement

Łukasz Szumowski: Conceptualization, Funding acquisition, Project administration, Supervision. Michał Orczykowski: Methodology, Validation, Visualization, Writing – review & editing. Jakub Malinowski: Data curation, Formal analysis, Investigation, Resources, Writing – original draft. Piotr Urbanek: Data curation, Investigation. Robert Bodalski: Data curation, Investigation. Andrzej Hasiec: Data curation, Investigation. Grzegorz Warmiński: Data curation, Investigation. Filip Machaj: Data curation. Magdalena Lipczyńska: Data curation, Investigation, Writing – review & editing. Ewa Warchoł-Celińska: Supervision, Writing – review & editing. Mirosław Kowalski: Investigation, Validation. Maciej Sterliński: Supervision. Maria Bilińska: Investigation, Validation.

Declaration of competing interest

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Lukasz Szumowski reports financial support was provided by Medical Research Agency, Warsaw, Poland. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Appendix A. Supplementary data

The following is the Supplementary data to this article: