Catheter ablation for tachyarrhythmia-induced cardiomyopathy in infants

Tachycardia-Induced Cardiomyopathy in an Infant with Atrial Flutter and Prolonged Recovery of Cardiac Function

Background: Tachycardia-induced cardiomyopathy (TIC) is caused by prolonged tachycardia, leading to left ventricular dilatation and systolic dysfunction with heart failure. Although TIC is more common in adults, it is rare in early infancy. Methods: Clinical testing was performed as part of medical evaluation and management. Next-generation sequencing (NGS) was conducted for a patient with TIC. A literature review on TIC was also conducted. Results: The case involved a 5-month-old infant referred to the hospital due to symptoms of heart failure lasting at least two months. The infant's heart rate was 200 beats per minute, the left ventricular ejection fraction fell below 14%, and electrocardiograms showed atrial flutter, suggesting TIC. After cardioversion, there was no recurrence of atrial flutter, and cardiac function improved 98 days after tachycardia arrest. The NGS did not identify any pathogenic variants. The literature review identified eight early infantile cases of TIC. However, no previous reports described a case with such a prolonged duration of TIC as ours. Conclusions: This is the first report of a case of prolonged TIC in a child with the documented time to recover normal cardiac function. The improvement of cardiac function depends on the duration of TIC. Early recognition and intervention in TIC are essential to improve outcomes for infantile patients, as timely treatment offers the potential for recovery.

The Effect of Accessory Pathway Location on Cardiac Function in Adult Patients with Wolff-Parkinson-White Syndrome

Introduction

The relationship between ventricular pre-excitation and left ventricular dysfunction has been described in the absence of sustained supraventricular tachycardia in a series of case reports. However, there have been no systematic studies about the effect of ventricular pre-excitation on cardiac function in adult patients with different accessory pathway locations.

Methods and Results

Patients were divided into four groups based on the type and location of their accessory pathway: septal, right free wall, left free wall, and concealed. N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, electrocardiogram recordings, electrophysiological properties, and transthoracic echocardiographic data (septal-to-posterior wall motion delay (SPWMD) and interventricular mechanical delay (IVMD) indicating intraventricular and interventricular dyssynchrony) were compared before and after successful ablation. Before radiofrequency catheter ablation, left ventricular ejection fraction (LVEF) was significantly lower in patients with septal and right free wall accessory pathways. Within three months after radiofrequency catheter ablation, NT-proBNP levels decreased, left ventricular function improved, and intraventricular left ventricular dyssynchrony disappeared. There was a negative correlation between initial LVEF with initial QRS duration and initial SPWMD. Notably, SPWMD had a stronger correlation with LVEF than initial QRS duration.

Conclusions

Anterograde conduction with a septal or right free wall accessory pathway may cause left ventricular dyssynchrony and impair left ventricular function. Intraventricular left ventricular dyssynchrony seems to be responsible for the pathogenesis of left ventricular dysfunction. Radiofrequency catheter ablation results in decreased NT-proBNP levels, normalized QRS duration, mechanical resynchronization, and improved left ventricular function.

Amiodarone and catheter ablation as cardiac resynchronization therapy for children with dilated cardiomyopathy and wolff-Parkinson-white syndrome

Preexcitation by accessory pathways (APs) is known to cause dyssynchrony of the ventricle, related to ventricular dysfunction. Correction of ventricular dyssynchrony can improve heart failure in cases of dilated cardiomyopathy (DCMP) with preexcitation. Here, we report the first case of a child with DCMP and Wolff-Parkinson-White (WPW) syndrome treated with amiodarone and radiofrequency catheter ablation (RFCA) in Korea. A 7-year-old boy, who suffered from DCMP and WPW syndrome, showed improved left ventricular function and clinical functional class after treatment with amiodarone to eliminate preexcitation. QRS duration and left ventricular ejection fraction (LVEF) were inversely correlated with amiodarone dosage. After confirming the reduction of preexcitation effects in DCMP, successful RFCA of the right anterior AP resulted in LVEF improvement, along with the disappearance of preexcitation. Our findings suggest that ventricular dyssynchrony, caused by preexcitation in DCMP with WPW syndrome, can worsen ventricular function and amiodarone, as well as RFCA, which should be considered as a treatment option, even in young children.

[Electrical heart diseases--therapy during childhood and adolescence]

With increasing experience, radiofrequency catheter ablation of tachyarrhythmia substrates has become first choice therapy for children >4 years of age with recurrent tachyarrhythmia. In younger patients, the risks associated with the procedure (typically procedure-related AV block or possible coronary artery damage) have to be weighed against the natural history of the tachyarrhythmia substrate, and the degree of control achieved with pharmacologic agents. Ablation for postoperative arrhythmias is more complicated, and associated with lower success rates and a higher rate of recurrence (of the same or a new tachyarrhythmia) despite acute procedural success. In this setting, catheter ablation has to be considered in conjunction with further surgery or the use of a defibrillator as a backup device to prevent arrhythmia-related sudden death. Also in inherited arrhythmias as in long QT syndrome and Brugada syndrome, implantable defibrillators have to be considered as a possible therapeutic option for patients with a higher risk for sudden cardiac death, irrespective of age.