Ivabradine: A Potential Therapeutic for Children With Refractory SVT

Keeping It "Current": A Review of Treatment Options for the Management of Supraventricular Tachycardia

OBJECTIVE

To review treatment options and updates that exist for the management of paroxysmal supraventricular tachycardia (PSVT).

DATA SOURCES

A literature search of PubMed was performed including articles from 1974 to June 2023 using the terms: arrhythmias, adenosine, verapamil, diltiazem, esmolol, propranolol, metoprolol, beta-blockers, amiodarone, PSVT, synchronized cardioversion, methylxanthines, dipyridamole, pediatrics, heart transplant, and pregnancy. Primary literature and guidelines were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Studies were considered if they were available in English and conducted in humans.

DATA SYNTHESIS

PSVT is a subset of supraventricular tachycardia (SVT) that presents as a rapid, regular tachycardia with an abrupt onset and termination. Due to frequent emergency department (ED) visits annually with symptoms of PSVT, appropriate and efficient management of these patients is vital. This review provides an overview of the pathophysiology of PSVT, while also describing the literature behind nonpharmacologic and pharmacologic management of PSVT.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review describes new literature regarding the improved success of the modified Valsalva maneuver as a nonpharmacologic therapy in PSVT. In addition, it describes a new technique in administration of adenosine that has improved outcomes, defines dose adjustments needed for drug interactions with adenosine, compares the utilization of nondihydropyridine calcium channel blockers with adenosine, and provides management recommendations for patients in special populations.

CONCLUSIONS

With high annual rates of ED visits for SVT, providers should be aware of the data behind management and modifications of therapy based on patient-specific factors (ie, patient preference, pharmacokinetics/pharmacodynamics, drug interactions, and special populations).

Pharmacological Management of Cardiac Arrhythmias in the Fetal and Neonatal Periods: A Scientific Statement From the American Heart Association: Endorsed by the Pediatric & Congenital Electrophysiology Society (PACES)

Disorders of the cardiac rhythm may occur in both the fetus and neonate. Because of the immature myocardium, the hemodynamic consequences of either bradyarrhythmias or tachyarrhythmias may be far more significant than in mature physiological states. Treatment options are limited in the fetus and neonate because of limited vascular access, patient size, and the significant risk/benefit ratio of any intervention. In addition, exposure of the fetus or neonate to either persistent arrhythmias or antiarrhythmic medications may have yet-to-be-determined long-term developmental consequences. This scientific statement discusses the mechanism of arrhythmias, pharmacological treatment options, and distinct aspects of pharmacokinetics for the fetus and neonate. From the available current data, subjects of apparent consistency/consensus are presented, as well as future directions for research in terms of aspects of care for which evidence has not been established.

Hyperpolarization-activated cyclic nucleotide-gated channel inhibitor in myocardial infarction: Potential benefits beyond heart rate modulation

Myocardial infarction (MI) and its associated complications including ventricular arrhythmias and heart failure are responsible for a significant incidence of morbidity and mortality worldwide. The ensuing cardiomyocyte loss results in neurohormone-driven cardiac remodeling, which leads to chronic heart failure in MI survivors. Ivabradine is a heart rate modulation agent currently used in treatment of chronic heart failure with reduced ejection fraction. The canonical target of ivabradine is the hyperpolarization-activated cyclic nucleotide-gated channels (HCN) in cardiac pacemaker cells. However, in post-MI hearts, HCN can also be expressed ectopically in non-pacemaker cardiomyocytes. There is an accumulation of intriguing evidence to suggest that ivabradine also possesses cardioprotective effects that are independent of heart rate reduction. This review aims to summarize and discuss the reported cardioprotective mechanisms of ivabradine beyond heart rate modulation in myocardial infarction through various molecular mechanisms including the prevention of reactive oxygen species-induced mitochondrial damage, improvement of autophagy system, modulation of intracellular calcium cycling, modification of ventricular electrophysiology, and regulation of matrix metalloproteinases.

Ivabradine in a 15-day-old male neonate with refractory focal atrial tachycardia

Ivabradine is used to reduce heart rate in children with chronic heart failure and dilated cardiomyopathy, it has recently been used off-label to treat tachyarrhythmias such as ectopic atrial tachycardia and junctional ectopic tachycardia (JET) in children. We report a successful ivabradine experience in a male neonate with refractory focal atrial tachycardia (FAT).

Combination Therapy of Ivabradine with Procainamide for the Management of Pediatric Postoperative Junctional Ectopic Tachycardia

Pediatric postoperative junctional ectopic tachycardia (JET), although usually self-limited, may lead to significant morbidity and mortality. Anti-arrhythmic medications are often necessary to restore atrioventricular synchrony when non-pharmacological measures fail. Multiple drugs have been described for the management of postoperative JET, with enteral ivabradine being the latest addition. While safe administration of ivabradine has been described in combination with other anti-arrhythmics (amiodarone, flecainide), no study has described the use of ivabradine in conjunction with intravenous procainamide for the management of postoperative JET. Our case report describes the safe use of ivabradine and procainamide combination therapy in a young patient.

Antiarrhythmic Drug Dosing in Children-Review of the Literature

Antiarrhythmic drugs represent a mainstay of pediatric arrhythmia treatment. However, official guidelines and consensus documents on this topic remain scarce. There are rather uniform recommendations for some medications (including adenosine, amiodarone, and esmolol), while there are only very broad dosage recommendations for others (such as sotalol or digoxin). To prevent potential uncertainties and even mistakes with regard to dosing, we summarized the published dosage recommendations for antiarrhythmic drugs in children. Because of the wide variations in availability, regulatory approval, and experience, we encourage centers to develop their own specific protocols for pediatric antiarrhythmic drug therapy.

Ivabradine monotherapy in pediatric patients with focal atrial tachycardia: a single-center study

This study investigated the efficacy of ivabradine monotherapy in pediatric patients with focal atrial tachycardia (FAT). We prospectively enrolled 12 pediatric patients (7.5 ± 4.5 years; six girls) with FAT who were resistant to conventional antiarrhythmics and received ivabradine as monotherapy. Patients were classified as having tachycardia-induced cardiomyopathy (TIC) if they had a left ventricular ejection fraction (LVEF) of < 50% and a left ventricular end-diastolic dimension (LVDD) z-score of > 2 due to tachycardia. Oral ivabradine was initiated at 0.1 mg/kg every 12 h, increased to 0.2 mg/kg every 12 h if no restoration of stable sinus rhythm was observed after two doses, and discontinued after 48 h if neither rhythm nor heart rate control was observed. Of these patients, six (50%) had incessant atrial tachycardia, and 6 had frequent short episodes of FAT. Six patients were diagnosed with TIC, and their mean LVEF and mean LVDD z-score were 36.2 ± 8.7% (range, 27-48%) and 4.2 ± 1.7 (range, 2.2-7.3), respectively. Finally, six patients achieved either rhythm (n = 3) or heart rate control (n = 3) within 48 h of ivabradine monotherapy. One patient achieved rhythm/heart rate control with ivabradine at a dose of 0.1 mg/kg every 12 h, while the others achieved rhythm/heart rate control at a dose of 0.2 mg/kg every 12 h. Five patients received ivabradine monotherapy for chronic therapy, one (20%) of whom had FAT breakthrough 1 month after discharge, and metoprolol was added. Neither FAT recurrence nor adverse effect (with or without beta-blocker) was observed during a median follow-up of 5 months.

CONCLUSION

Ivabradine is well-tolerated and may provide early heart rate control in pediatric FAT and can be considered early, especially in the presence of left ventricular dysfunction. Further investigations are deserved to confirm the optimal dose and long-term efficacy in this population.

WHAT IS KNOWN

• Focal atrial tachycardia (FAT) is the most common arrhythmia associated with tachycardia-induced cardiomyopathy (TIC) in children, and the efficacy of conventional antiarrhythmic medications in the treatment of FAT is poor. • Ivabradine is currently the only selective hyperpolarization-activated cyclic nucleotide-gated (HCN) inhibitor, which can effectively low HR without negative effect on blood pressure or inotropy.

WHAT IS NEW

• Ivabradine (0.1-0.2 mg/kg every 12 h) can effectively suppress focal atrial tachycardia in 50% of pediatric patients. • Ivabradine provides early control of heart rate and hemodynamic stabilization in children with severe left ventricular dysfunction due to atrial tachycardia within 48 h.