Successful medical management of recurrent atrial arrhythmia in a non-eligible Fontan patient to ablation: case report and literature review

Abstract

Introduction:

A non-neglected subgroup of patients with Fontan circulation will develop arrhythmias during their lives, which may be due either to the underlying congenital heart disease itself or as a result of surgical or structural interventional treatment.

Case presentation:

We report the case of a 38-year-old woman, known to have a single ventricle congenital heart disease, at the age of 6, benefited from palliative correction by the intra-cardiac Fontan procedure and who, at the age of 35 years, developed focal intra-atrial tachycardia by macro reentry, who underwent ablation with complete isolation of the rest of the right atrium after Fontan fenestration. The evolution was marked by the onset of dyspnea with cyanosis requiring closure of the fenestration, as well as a recurrence of supra-ventricular arrhythmia that was successfully reduced by a triple association of maximum-dose metoprolol, maximum-dose diltiazem, and amiodarone.

Discussion:

In general, the management of intra-atrial tachycardia in Fontan is based on the following pillars: First, effective anticoagulation, then arrhythmia management by means of antiarrhythmic drugs, catheter ablation, anti-bradycardia and anti-tachycardia atrial pacing, and Fontan conversion with arrhythmia surgery. Although medical treatment is characterized by a high recurrence rate, it will be an important alternative when ablation is unavailable or not feasible for technical reasons of the type of montage performed.

Conclusion:

Arrhythmias represent one of the serious problems that the majority of patients with Fontan circulation will face at some time, and management of these arrhythmias remains essential given the compromise of hemodynamic function.

Introduction

The population of patients with congenital heart disease (CHD) is continually increasing, with more and more adults patients. A significant sub-group of this patient population will develop arrhythmias during their lifetime, which may be due either to the underlying heart malformation itself or as a result of surgical or structural interventional treatment^[1^]. If the management of arrhythmias in patients without CHD has seen real progress over the last 20 years, with the development of anti-arrhythmic medical treatment, the introduction of catheter ablation therapies, and 3D mapping systems, then the management of arrhythmias in patients with CHD has followed the same development curve, but with more complexity in terms of therapeutic management^[2^]. Therefore, the management of arrhythmias in this population requires a thorough understanding of the anatomy and nature of the malformation, as well as a detailed knowledge of the natural history of the arrhythmia and its relationship with a possible repair procedure, in order to decide on the best therapeutic choice^[3^]. This case report was submitted in accordance with the case report^[4^], criteria, and TITAN Guideline^[5^].

HIGHLIGHTS

• Arrhythmias represent one of the serious problems that the majority of patients with Fontan circulation will face at some time.

• The management of intra-atrial tachycardia in Fontan patient’s is based on the following pillars: First, effective anticoagulation, then, ideally, catheter ablation and maintenance of sinus rhythm.

• The structural, hemodynamic, and anatomical constraints in these patients result in a significantly higher rate of recurrence of supraventricular arrhythmia.

Case presentation

We report the case of a 38-year-old woman with known congenital single ventricle heart disease (right ventricular hypoplasia and pulmonary valve atresia) who, at the age of 6 years, had undergone palliative correction with the Fontan intracardiac procedure via a direct anastomosis between the superior vena cava and the pulmonary artery (PA), and insertion of an intra-atrial conduit between the inferior vena cava (IVC) and the PA, with good initial outcome.

At the age of 35 years, in 2019, and during the 18th week of her first pregnancy, the patient presented a regular tachycardia with narrow QRS complex at 150 bpm highly probable in favor of a common atrial flutter non-tolerated hemodynamically, requiring medical interruption of the pregnancy after performing an external electric shock, and the risk of subsequent pregnancy was well explained to the patient, so the decision was taken to insert a Mirena intra-uterine device, and the patient was put on metoprolol 100 mg daily with good clinical evolution.

One year later, in January 2020, the patient presented a recurrence of several episodes of tachycardia, with significant functional consequences and NYHA stage IV dyspnea. The patient was therefore proposed and accepted for ablation.

In May 2020, the patient benefited from electrophysiology exploration; after mapping with an HD-Grid catheter, reproducible arrhythmia induction was achieved with an isoprenaline injection, showing focal macroreentry intra-atrial tachycardia. An ablation procedure is performed with complete isolation of the rest of the right atrium (Fig. 1), after fenestration of the Fontan with an atrial flow regulating device (8 mm occlutech).

Figure 1.

Electromagnetic mapping showing ablation points.

One month after the procedure, the patient presented with recently worsening dyspnea with room air desaturation at 78% with general cyanosis requiring fenestration closure, then the patient was put on anticoagulant therapy with oral anti-vitamin K and metoprolol 100 mg daily.

Two years later, in May 2022, the patient consulted the emergency department for a recurrence of palpitations with rest dyspnea. On admission, the patient was found to be tachycardic at 150 bpm, with no signs of clinical intolerance and room air saturation of 88%. There was no evidence of discontinuation of treatment, infection, or use of any toxic or narcotic drugs. The ECG on admission showed regular QRS-plus tachycardia in favor of macroreentry intra-atrial tachycardia (Fig. 2). Biological findings were normal. We tried vagal maneuvers (Valsalva and sino-carotid massage) but without success.

Figure 2.

ECG on admission shows regular QRS-plus tachycardia in favor of macroreentry intra-atrial tachycardia.

We admitted the patient to a cardiac intensive care unit with continuous monitoring. Given this situation, and after the patient refused to undergo ablation treatment due to intolerance to fenestration following severe hypoxemia during the first episode, we opted for antiarrhythmic medical treatment alone in these cases.

Initially, we increased the dose of metoprolol to 200 mg per day, in combination with digoxin 0.25 mg per day, but to no avail. We then decided to combine metoprolol at maximum dose with diltiazem at 90 mg per day, but again to no avail. We tried electrical cardioversion, but this was unsuccessful as the patient’s International Normalized Ratio was unstable and still below the target range (2–2.5). Last, we decided to combine triple therapy with maximum-dose metoprolol, maximum-dose diltiazem, and amiodarone 200 mg daily, and finally succeeded in restoring sinus rhythm (Fig. 3) with a mean HR between 60 and 85 bpm.

Figure 3.

ECG at discharge shows sinus rhythm.

We opted for this therapeutic strategy for an initial period of one month, followed by reassessments at 3 and then 6 months to monitor the adverse effects of amiodarone, which were monitored by measuring thyroid hormone levels and watching for clinical signs of photosensitivity or respiratory intolerance, none of which were observed in our patient during the 1-year follow-up period.

Our patient’s 1-year follow-up showed her to be asymptomatic with no further tachycardia episodes and with good therapeutic tolerance.

Discussion

Supraventricular arrhythmias in patients with CHD are not uncommon and can still occur even 15 years after the heart disease has been corrected^[6^]. Possible pathophysiological mechanisms for this arrhythmia involve macroreentry circuits secondary to scar tissue, incisions and implanted prophetic material^[7^]. In patients with a Fontan circuit, macroreentry intra-atrial tachycardia remains the most frequent atrial tachycardia, mainly when a direct atrio-pulmonary montage is involved and less so when an intra-atrial tunnel or extracardiac Fontan is involved. The management of this type of tachycardia is not as simple, as previously mentioned, given the complexity of the cardiopathy itself on the one hand, but also of the repair montages performed, and must be shared between a cardiac surgeon, a congenital cardiologist, and a rythmologist cardiologist^[7^].

The particularity of arrhythmias in patients with Fontan circulation is represented by the long duration between the postoperative interval and the first arrhythmogenic episode, and this usually coincides with other associated comorbidities, secondary to the circulation itself, such as heart failure, hepatic, renal, and intestinal dysfunction, which makes the management of this arrhythmia relatively complex, and for these reasons, the prognostic impact of arrhythmias in patients with Fontan circulation is well established^[8^].

The management of supraventricular tachycardias in patients with Fontan circulation does not differs from that in patients without CHD in terms of the basics of management, but the complexity and efficacy of treatment are much less proven in these patients. As already noted, the structural, hemodynamic, and anatomical constraints in these patients not only make it difficult to achieve a good outcome in terms of rhythm control but also result in a significantly higher rate of recurrence^[9,10^].

In summary, the management of intra-atrial tachycardia in Fontan patient’s is based on the following pillars: First, effective anticoagulation, then, ideally, catheter ablation and maintenance of sinus rhythm. However, this is only possible in rare cases, given the complexity of ablation in these patients on the one hand and the high rate of recurrence on the other. As far as anticoagulation is concerned, it has been shown that there is no difference between the assessment of thromboembolic risk in patients with atrial fibrillation and atrial tachycardia in these patients, which is why effective anticoagulation will be based on assessment by the CHA2DS-VAS2C Score^[10^]. This anticoagulation should be provided by an anti-vitamin K; however, to date, no solid evidence is available to allow anticoagulation by the new direct oral anticoagulants (NOACs), although several reports have reported safe use of the NOACs in patients^[11–13^].

Therapeutic options for arrhythmia management include antiarrhythmic drugs, catheter ablation, antibradycardia and antitachycardia atrial pacing, and Fontan conversion with arrhythmia surgery^[14^]. The main aim is to put an end to the arrhythmia as quickly as possible, to avoid hemodynamic decline and atrial remodeling, which will reinforce the arrhythmogenic mechanism. Except in a state of hemodynamic instability, where electrical cardioversion is indicated from the outset. The management of arrhythmias in stable patients requires a thorough hemodynamic assessment, as well as an evaluation of liver, kidney, lung, and thyroid function, and an accurate assessment of the efficacy of the Fontan circulation, in order to choose the best molecule^[2^].

Injectable betablockers represent the first-line treatment associated with calcium channel blockers, with efficacy results reaching 100% for the injectable form and 88% for the oral form in a German study. Combination with amiodarone will help to prevent recurrences and is particularly useful in patients with systemic ventricular dysfunction or hypertrophy, as well as coronary artery disease. However, the frequent adverse effects of this molecule mean that its long-term use is limited, especially in young subjects^[2,14^]. Although triple therapy combining beta-blockers, calcium channel blockers, and amiodarone remains effective for controlling heart rate and rhythm, the major risk is conduction disorders, which makes long-term maintenance of this triple therapy a risk strategy.

Although catheter ablation of arrhythmogenic substrates gives better results than medical treatment, achieving efficacy between 54 and 94%, but compared with other CHDs, this technique is associated with lower success rates and with as early a recurrence of tachycardia in ≈ 50% of patients^[9,15^].

Precise identification and detection of arrhythmogenic sites is the most important step in ablation and has become increasingly easier with the advent of contact and non-contact three-dimensional electro-anatomical mapping systems^[16^].

As for the long-term outcome of ablation, the literature is relatively lacking in this respect, with only a few studies describing ablation success rates and long-term results specifically in patients with Fontan circulation^[16^].

In a European multicenter study, 19 patients (aged 29 ± 9 years) with single-ventricle hearts: A supraventricular arrhythmia developed (18 ± 9 years) after the initial surgical intervention and was predominantly IART, and ablation was performed (6 ± 5 years) after the initial arrhythmia episode with multiple ablation procedures in 10 patients. These results demonstrate the recurrent character of these arrhythmias, which can be explained by progressive atrial cardiomyopathy rather than by an unsuccessful ablation procedure or by the arrhythmogenicity of lesions prior to ablation. However, despite these recurrences, 72% of patients remained in sinus rhythm at long-term follow-up^[15^].

A 20-year retrospective study included 162 patients with a Fontan atrio-pulmonary or atrio-ventricular connection. Atrial arrhythmia was revealed in 18.5% (N = 30) of survivors. Mapping performed prior to ablation showed that the main arrhythmogenic sites were located in the region between the inferior vena cava and the tricuspid annulus or the inferior border of the lateral arteriotomy scar, and the ablation success rate after 3 years of follow-up was 85%^[17^].

Finally, surgical conversion represents an alternative, especially in patients with an atriopulmonary connection, who will be converted to an intra-atrial lateral or extracardiac connection, combined with intraoperative removal of potential atrial tachycardia circuits and excision of a large part of the dilated free wall of the atrium^[1^].

Almost all patients report an improvement in New York Heart Association class within 1 year of conversion. Whereas for the success rate, the main obstacles are the type and duration of arrhythmia, the anatomy and function of the systemic ventricle, and the size of the left and right (remaining) atria or the single atrium^[18,19^].

Patient perspective

In our patient, the initial strategy was to manage the arrhythmia issue, but given the high risk of recurrence, even though sinus rhythm was restored, we can discuss the possibility of atrioventricular junction ablation with pacemaker implantation. This may remain one of the treatment options for her, but given her intolerance to fenestration and her young age, heart transplantation in the short term is one of the best treatment options for her.

Conclusion

Arrhythmias represent one of the serious problems that the majority of patients with Fontan circulation will face at some time, and management of these arrhythmias remains essential given the compromise of hemodynamic function. Although medical treatment is characterized by a high recurrence rate, it will be an important alternative when ablation is not available or not feasible for technical reasons of the type of montage performed.

Ethical approval

The ethical committee approval was not required give the article type (case report). However, the written consent to publish the clinical data of the patients was given and is available to check by the handling editor if needed.

Consent

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

Sources of funding

No funding sources.

Author contributions

M.M. is the first author who contributed to this research in write up and collating data. A.B. is the second author who contributed to the study concept, data analysis, and collection. Z.B., N.S., and N.E. have supervised and validated the final version.

Conflicts of interest disclosure

The authors declare that they have no financial conflict of interest with regard to the content of this report.

Research registration unique identifying number (UIN)

This is not an original research project involving human participants in an interventional or an observational study but a case report. This registration is was not required.

Guarantor

Manal Msirdi.

Provenance and peer review

Not commissioned, externally peer reviewed.

Data availability statement

The data underlying this article are available only in the article.