Effect analysis of radiofrequency catheter ablation in the treatment of 7 children with atrial tachycardia-induced cardiomyopathy

Abstract

Background

Tachycardia-induced cardiomyopathy refers to changes in cardiac structure and function that result from rapid arrhythmia and can manifest as a continuous or recurrent event. Cardiomyopathy induced by atrial tachycardia is typically reversible if the arrhythmia is effectively controlled. There are few literature reports of atrial tachycardia-induced cardiomyopathy in children, and fewer cases have been effectively treated by radiofrequency catheter ablation in children.

Objective

we conducted a clinical summary of 7 cases of atrial tachycardia-induced cardiomyopathy in children in Wuhan Children’s Hospital to investigate the effectiveness and safety of radiofrequency catheter ablation for atrial tachycardia-induced cardiomyopathy.

Methods

A total of 7 children (4 girls and 3 boys) diagnosed with atrial tachycardia-induced cardiomyopathy and admitted to Wuhan Children’s Hospital from January 2017 to April 2024 were selected. An intracardiac electrophysiological study was conducted on all 7 children to verify the origin of the atrial tachycardia and the presence of decreased cardiac function. All children were followed up for a period ranging from 2 to 12 months after RFCA or atrial appendectomy. During this follow-up, left ventricular end-diastolic diameter and left ventricular ejection fraction were monitored.

Results

The age range was 3.6 to 13 years and the median age was 11.2 years. The weight range was from 15 to 92 kg, the average weight was 34 kg. The results of the intracardiac electrophysiological study of the 7 cases showed that the origin came from the right pulmonary vein in 2 cases, from the left pulmonary vein in 2 cases, from the left atrial appendage in one case, and from the right atrial appendage in 2 cases. Four cases of tachycardia-induced cardiomyopathy originating in the left and right pulmonary veins were successfully eliminated by radiofrequency catheter ablation (RFCA). The foci of atrial tachycardia were located in the atrial appendages of three children. For two of them, after precise positioning by the atrium three-dimensional electroanatomic mapping system and performing RFCA, the atrial tachycardia briefly stopped for approximately 24 h before reoccurring, and atrial appendectomy was subsequently performed. Nevertheless, in the other child, whose focus of atrial tachycardia was in the right atrial appendage, the lesion was successfully eliminated by RFCA. After RFCA or in combination with atrial appendectomy, 6 children were followed for more than 1 year and 1 child for 2 months. All children had sinus rhythm. At the same time, the left ventricular ejection fraction after RFCA or combined atrial appendectomy was significantly increased in 7 cases, indicating statistical significance (P = 0.018)), but the left ventricular end-diastolic diameter was not statistically significant in the treatment (P = 0.203)).

Conclusions

Sustained atrial tachycardia can lead to the occurrence of cardiomyopathy such as cardiac enlargement and heart failure. RFCA and combined atrial appendectomy can effectively stop tachycardia, eliminate the mechanism of tachycardia, and allow complete recovery of cardiac function.

Focal atrial tachycardia is an automatic and rapidly discharging non-sinusoidal focus originating in the atrium, which is a rare cause of supraventricular tachycardia in children [1, 2]. Atrial tachycardia (AT) is a form of supraventricular tachycardia with a prevalence of 0.34–0.46% in adults. However, the prevalence of AT is higher in children and prolonged tachycardia occurs, resulting in tachycardia-induced cardiomyopathy, which is reversible if the arrhythmia can be treated effectively [3–6]. In children ≥ 3 years of age, antiarrhythmic drugs usually have an unsatisfactory effect in the treatment of focal atrial tachycardia, especially in children with tachycardia-induced cardiomyopathy. In such cases, radiofrequency catheter ablation should be considered at the earliest opportunity [1, 7]. Since there are few literature reports on children with atrial tachycardia-induced cardiomyopathy, this article summarizes the clinical findings of children with atrial tachycardia-induced cardiomyopathy diagnosed in the cardiovascular department of Wuhan Children’s Hospital in the past seven years, discusses the characteristics and effectiveness of RFCA for the disease.

Patients

A retrospective analysis was conducted on 7 children diagnosed with atrial tachycardia-induced cardiomyopathy in the intracardiac electrophysiological study admitted to the cardiovascular department of Wuhan Children’s Hospital from January 2017 to April 2024, including three boys and four girls. The age range was 3.6 to 13 years, with a median age of 11.2 years. The weight range was from 15 to 92 kg, the average weight was 34 kg. At admission, 12-lead electrocardiogram (Fig. 1), Holter electrocardiogram, chest x-ray, and echocardiography were routinely examined as a pretreatment control. The test results of these children demonstrated that the diameter of the left ventricle increased significantly, the motion amplitude of the left ventricular wall decreased, the morphology and structure of the valves were normal, and the left ventricular ejection fraction (LVEF) declined.

Fig. 1.

Figure A shows atrial tachycardia and the lesion site is in the right pulmonary vein. Figure B shows atrial premature contractions and the lesion site is in the left pulmonary vein. Figure C shows a brief bout of atrial tachycardia focused in the right atrial appendage. Figure D shows a brief bout of atrial tachycardia focused in the left atrial appendage

These children suffering from heart failure were once treated with drugs such as digoxin, diuretics, angiotensin-converting enzyme inhibitors and beta-blockers. However, the therapeutic effect was not optimal. After the parents signed an informed consent, the children were examined using an intracardiac electrophysiological study and treated with RFCA. In this research, we considered a previously published case report and integrated it into this study for analysis and discussion, with the aim of in-depth study of the relevant issues related to atrial tachycardia-induced cardiomyopathy in children [8].

Methods

All 7 children underwent the intracardiac electrophysiological study and RFCA (with the assistance of saline infusion technique) under general anesthesia. Two intravenous lines were established in all children. Two quadripolar catheters were respectively placed into the coronary sinus and right ventricular apex through the left subclavian vein and the right femoral vein. When the focal of atrial tachycardia was in the left atrium, the ablation catheter was inserted into the left atrium via a septal puncture. We performed three-dimensional electroanatomic mapping (St. Jude Medical, St. Paul, MN, USA) on all children and conducted ablation at the site of the earliest activation sites. RFCA was performed under continuous temperature control mode to attain a target temperature of 43 °C. The radiofrequency energy starts at 20 watts and gradually increases to 30/35 watts to reach the target temperature.

Object of observation

Left ventricular end-diastolic diameter (LVDd) and left ventricular ejection fraction (LVEF) were recorded before and after RFCA.

Statistical analysis

SPSS 22.0 statistical software was used to perform statistical analysis of cardiac LVEF and LVDd before and after RFCA. Given the small sample size of these two datasets and their non-compliance with normal distribution, the Wilcoxon signed-rank test was adopted.

Results

The results of the intracardiac electrophysiological study showed in 7 cases that the origin was in the right pulmonary vein in 2 cases, in the left pulmonary vein in 2 cases, in the left atrial appendage in 1 case and in the right appendage in 2 cases (Table 1). Four children with atrial tachycardia-induced cardiomyopathy originating from the left and right pulmonary veins were successfully cured by RFCA, sinus rhythm and LVEF were completely normal during follow-up up to one year. In child No. 5 (Table 1), the focus of the atrial tachycardia was in the right atrial appendage, and RFCA effectively eliminated the lesion in the atrial appendage. However, in the other two children whose atrial tachycardia originated in the atrial appendage, the atrial tachycardia only persisted transiently during the RFCA procedure. As a result, these two children were transferred to the cardiothoracic surgery department the next day and underwent atrial appendectomy. In both cases, atrial tachycardia stopped immediately after removal of the atrial appendage.

Table 1.

Clinical characteristics of 7 children

Case	1*	2	3	4	5	6	7
Sex	girl	girl	boy	boy	girl	boy	girl
Age(year)	11.7	8.9	12.5	11.2	3.6	13	5.9
Weight (Kg)	55	28	92	38	15	34	23
Focus location	Right pulmonary vein	Right pulmonary vein	Left pulmonary vein	Left pulmonary vein	Right atrial appendage	Right atrial appendage	Left atrial appendage
Drugs for pre-RFCA.	digoxin, ACEIs	Propafenone	NO	NO	NO	Amiodarone, Metoprolol Tartrate	intravenous injection of deslanoside
LVEF before RFCA (%)	15	39	48	47	42	45	28
LVEF after RFCA (%)	46	63	64	64	53	52	46
LVEF after 1 year of RFCA (%)	/	63	65	64	63	60	63
Left ventricle dilated before RFCA?	Yes	Yes	Yes	NO	Yes	Yes	Yes
LVDd before RFCA (mm)	56	40	55	36	43	45	46
LVDd after RFCA (mm)	57	39	53	39	37	43	37
NT-pro-BNP (pg/ml)	8066	429	80	136	9000	181	2768
Hs-cTnT (ng/ml)	0.044	0.05	0.05	0.05	0,068	0.066	0.013
CK-MB (U/L)	21	25	13	19	14	17	17
Energy doses of irrigated RF	30w/43℃	35w/43℃	30w/43℃	30w/43℃	35w/43℃	35w/43℃	30w/43℃
Application times of irrigated RF	60 S*4	90 S*3	30 S*5	30 S*5	60 S*4	60 S*4	40 S*5
Time of RFCA and atrial appendectomy	3 h	2 h 10 min	2 h 20 min	2 h	2 h	1h40min + 1 h	3 h + 1 h 10 min

ACEIs, angiotensin-converting enzyme inhibitors, LVDd, left ventricular end-diastolic diameter, LVEF, left ventricular ejection fraction, NT-proBNP: N-terminal pro-B type natriuretic peptide, Hs-cTnT: hypersensitive cardiac troponin T, CK-MB: Creatine Kinase myocardial band

The symbol * indicates that pediatric patient number 1 has been followed up for less than a year and is currently in follow-up status

The statistical results of SPSS 22.0 in the study show that there was a significant difference in LVEF before and after RFCA and atrial appendectomy (P = 0.018), suggesting that RFCA or combined atrial appendectomy had a positive effect on the Improve systolic heart function in children. However, regarding LVDd there was no statistical significance before and after RFCA and combined atrial appendectomy (P = 0.203), suggesting that the improvement in LVDd was not obvious. RFCA or combined atrial appendectomy had a good and statistically significant effect on improving LVEF in atrial tachycardia-induced cardiomyopathy, but not in LVDd (Fig. 2).

Fig. 2.

Figure A shows the variations of left ventricular ejection fraction before and after radiofrequency catheter ablation in different children. Figure B shows the status of left ventricular end-diastolic diameter (LVDd) before and after radiofrequency catheter ablation in different children

Follow-up status of 6 children 1 year after RFCA

Six of the seven children were followed for 1 year after RFCA, and none of the children had atrial tachycardia or atrial rhythm. One month after RFCA, LVEF returned to normal and remained normal at follow-up one year later. Child number 1 (indicated with an asterisk * in Table 1) was asymptomatic at the two-month follow-up and the ECG did not show atrial tachycardia, but the LVEF was still recovering, so the child continued to receive oral captopril and was monitored closely.

Discussion

Tachycardia in adults is mainly caused by atrial fibrillation [2, 4], while the site of origin of the lesion of atrial tachycardia in children is usually in the special anatomical structure of the atrial folds. Because it is difficult for children to clearly express their symptoms in words, they are often not recognized until obvious clinical symptoms appear [9]. At this point, their heart failure situation may be more severe than in adults. According to the report by Subhani F et al., focal atrial tachycardia, which accounts for about 10% or even more percent of supraventricular tachycardia in adults [10] is characterized by the centrifugal propagation of depolarized waves from a well-defined focus in the atrial tissue and does not require any other part of the conduction system for propagation. It has been reported in some literature that atrial tachycardia and other supraventricular tachycardias with rapid ventricular rate can cause cardiomyopathy [11]. An article we published also mentioned that the pathological mechanism of atrial tachycardia cardiomyopathy mainly includes cardiomyocyte changes, abnormal energy metabolism and Ca²⁺ processing disorders. Activation of the neurohumoral system also plays an important role [8].

The features of children with atrial tachycardia-induced cardiomyopathy [4, 12–14] are similar to those of dilated cardiomyopathy on echocardiography. but the left ventricular function of children with atrial tachycardia-induced cardiomyopathy can be significantly improved after effective control and the prognosis is better [2]. The 7 children we reported met the definition criteria for tachycardia-induced cardiomyopathy: (1) left ventricular ejection fraction < 50% with complete ventricular hypokinesia; (2) No underlying structural heart disease; (3) Left ventricular ejection fraction improved by > 15% after effective treatment of tachycardia [14]. Haiyan Ge et al. reported that the incidence of atrial tachycardia cardiomyopathy in children was 22.6% [6]. In this study, we presented 7 cases of atrial tachycardia-induced cardiomyopathy, and explained their clinical features, such as the origin of atrial tachycardia and the changes in LVEF. Regarding other RFCA cases associated with this disease, we have referred to relevant literature to support the efficacy and safety of RFCA in the treatment of atrial tachycardia-induced cardiomyopathy [15].

Atrial tachycardia usually arises from the special anatomical structure of the ventricle with folds. The main reason is that during embryonic development, part of the myocardial tissue remains in the fold, which can become the focus of atrial arrhythmia in later stages. Faryal Subhani, et al. reported that the most common locations of right atrial tachycardia include the coronary sinus orifice, the oblique region, and the tricuspid annulus [10]. Raphael Rosso reported that the lesion in the left atrium is often located at the opening of the pulmonary vein [2], the left atrial appendages, left nasal septum, and mitral ring are uncommon locations [2, 10, 16, 17]. Our research also confirms these results. Nevertheless, our study has a comparatively small sample size and has a certain degree of bias. In the future, additional data will be required for verification.

Treatment options for atrial tachycardia-induced cardiomyopathy include drug and non-drug therapies. Drug therapy includes β-blockers, class Ic antiarrhythmics (propafenone, etc.), calcium antagonists, amiodarone, etc. [18, 19]. However, drug therapy can only change the electrophysiology of tachycardia, but cannot eliminate the mechanism of tachycardia [9, 20]. At the same time, the drug itself is toxic; In particular, the arrhythmogenic effect of antiarrhythmic drugs cannot be overlooked.

Non-drug treatments include RFCA, atrial appendectomy, etc. RFCA should be the preferred treatment to eliminate the mechanism of tachycardia [20, 21] and avoid drug toxicity. The intracardiac electrophysiological study can clearly reveal the location and mechanism of atrial tachycardia before RFCA [20, 21], especially atrial tachycardia in the atrial appendage. Not only can RFCA achieve precise localization based on the electrophysiological study, but it can also be attempted to remove the lesion. However, RFCA here is prone to myocardial perforation and pericardial tamponade due to the thin wall of the atrial appendage, and radiofrequency energy cannot be effectively released due to the influence of the lactoid muscle in the atrial appendage. Thus, in our report, after combining the electrophysiological study and RFCA attempts, two cases were immediately referred for cardiothoracic surgery for atrial appendectomy under general anesthesia the next day to eliminate the lesion. Therefore, atrial tachycardias in the atrial appendage were first subjected to intracardiac electrophysiological localization and RFCA to determine the precise location of the lesion, and radiofrequency energy release could be attempted. If the lesion cannot be eliminated by radiofrequency energy, subsequent atrial appendectomy is the ultimate treatment after RFCA failure.

The mean recovery time (LVEF ≥ 50%) for atrial tachycardia-induced cardiomyopathy was 25.46 ± 24.76 days (2–94 days) [6]. Clinical trials have also reported improvements in LVEF within one month of tachycardia correction; However, full recovery can take 2 to 3 months and rarely longer than 6 months [4]. The LVEF of the 6 children we reported returned to normal 1 month after RFCA. Currently, there was only one child whose cardiac LVEF did not fully normalize in the second month after RFCA, but the LVEF gradually recovered. The child’s sinus rhythm was maintained, the child did not show any pleasant clinical symptoms, and was followed up regularly.

Our investigations found that these children had all manifestations of cardiomyopathy with reduced cardiac function, including clinical symptoms such as abdominal pain, reduced cardiac function and even syncope. Given the limitations of oral antiarrhythmic drugs, we adopted RFCA as an active, safe, effective, and rapid treatment approach. Meanwhile, RFCA technology in our hospital in central China has taken a leading position in the treatment of cardiac arrhythmias in children. Therefore, the RFCA was performed after thorough communication with parents and obtaining their consent. It is unfortunate that the introduction of epicardial RFCA and cryoablation therapy has not yet been implemented in our hospital and this represents a shortcoming on our part.

Our data showed that RFCA had a good and statistically significant effect on improving LVEF in atrial tachycardia-induced cardiomyopathy, but not in LVDd. Because the sample size of children with atrial tachycardia-induced cardiomyopathy is relatively small, the sample size we chose is also limited. Further data statistics and summaries will be the focus of our research in the future.

Abbreviations

AT

Atrial tachycardia

RFCA

Radiofrequency catheter ablation

ECG

Electrocardiogram

LVDd

Left ventricular end-diastolic diameter

LVEF

Left ventricular ejection fraction

Author contributions

Study conception and design: M.Z.; data collection: M.Z., X.X.C., Suqiong Ji, Mohammadreza Kosari; analysis and interpretation of results: X.X.C., M.Z. and Y.Z.; draft manuscript preparation: M.Z., All authors reviewed the results and approved the final version of the manuscript.

Funding

This work was no funding support.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

Ethical approval was obtained by the ethical committee of Wuhan Children’s Hospital. Parents of the patient provide written informed consent for the publication of the personal data and accompanying images presented in this manuscript.

Consent for publication

Written informed consent was obtained from the patient’s legal guardians for publication of this case report and any accompanying images.

Competing interests

The authors declare no competing interests.