BRIEF RESEARCH REPORT article

Front. Pharmacol., 18 February 2025

Sec. Cardiovascular and Smooth Muscle Pharmacology

Volume 16 - 2025 | https://doi.org/10.3389/fphar.2025.1502375

Ivabradine in treatment of symptomatic heart failure and supraventricular tachycardias in patients under six months of age

  • 1. Pharmacy Department, Vall d’Hebron University Hospital, Barcelona, Spain

  • 2. Pediatric Cardiology Department, Vall d’Hebron University Hospital, Barcelona, Spain

  • 3. Neonatology Department, Vall d’Hebron University Hospital, Barcelona, Spain

Abstract

Background:

Although heart failure (HF) and supraventricular tachycardias (SVT) are associated with high morbidity and mortality in pediatrics, especially, in children under 6 months; the efficacy of available treatments is limited, requiring the use of off-label therapies. The aim of the study is to investigate the efficacy, dosage, and safety of off-label ivabradine in patients under 6 months of age with HF or SVT.

Methods:

Retrospective observational study, which included patients under 6 months of age with HF or SVT who received ivabradine between January 2020 - May 2024. Demographic, clinical, and treatment-related variables were collected. Response variables were established according to indication, HF: heart rate (HR) and left ventricular ejection fraction (LVEF); SVT: HR.

Results:

Thirteen patients (nine women) with a median age of 1.4 (1-4) months were included. Ivabradine was discontinued in five of the seven HF patients due to resolution of HF, control of HR, and improvement of LVEF. One patient discontinued ivabradine because of bradycardia. In the SVT group, four of the seven patients discontinued ivabradine after the resolution of tachyarrhythmia and improvement of HR. Two patients experienced bradycardia but did not require treatment discontinuation. HR reduction was statistically significant in both groups. In HF, the median initial ivabradine dose was 0.06 mg/kg/day and the maintenance dose was 0.2 mg/kg/day. In SVT, the initial and maintenance doses were 0.1 mg/kg/day and 0.24 mg/kg/day, respectively.

Conclusion:

Ivabradine demonstrated favorable efficacy and safety results in patients under 6 months of age with HF or SVT.

Highlights

  • • First published study that reports the use of ivabradine in patients under 6 months of age with heart failure.

  • • Study with the largest cohort of patients under 6 months who have received ivabradine for a diagnosis of supraventricular tachycardia.

  • • Ivabradine improved clinical parameters with an appropriate safety profile in patients under 6 months with heart failure and supraventricular tachycardia, presenting an effective and safe therapeutic alternative.

  • • Reduction in heart rate in patients with heart failure and supraventricular tachycardia was statistically significant.

1 Introduction

Heart failure (HF) and cardiac arrhythmias are significant causes of morbidity and mortality in the pediatric population, particularly during the perinatal period (; ).

1.1 Heart failure (HF)

Congenital heart diseases (CHD) represent the leading cause of HF in the pediatric population (). Approximately 90% of patients with CHD develop HF within the first year of life, with the highest incidence occurring during the first 6 months (). The second most common cause of HF are primary cardiomyopathies, particularly dilated cardiomyopathy (DCM), which has a higher incidence and worse prognosis in patients under 1 year of age (; ).

Currently, the treatment of HF aims to alleviate symptoms, slow disease progression, and reduce associated mortality. To achieve this, therapies that improve cardiac function and decrease heart rate (HR) are necessary, as elevated HR values are sometimes associated with an increased risk of death (). However, the heterogeneity of the condition and its low incidence make standardizing treatment in pediatrics challenging (). Guidelines recommend the use of diuretics, digoxin, angiotensin-converting enzyme inhibitors (ACEIs), aldosterone antagonists, and beta-blockers (; ). Nonetheless, due to the lack of evidence and controlled clinical trials in pediatric patients, treatment recommendations are often extrapolated from adult data. Consequently, most drugs are not approved for pediatric use ().

1.2 Supraventricular tachycardias (SVT)

Tachyarrhythmias, a subset of cardiac arrhythmias, are characterized by heart rates exceeding the normal limits for age, with supraventricular tachycardias (SVT) being the most common in pediatrics (). The age distribution of pediatric SVT is bimodal, with peaks occurring in infants under 1 year and in children between seven and 12 years of age (). SVT typically present in patients without structural heart disease, although it can also be associated with CHD or cardiomyopathies, as well as secondary to surgical interventions ().

SVT include conditions such as junctional ectopic tachycardia (JET), focal atrial tachycardia (FAT), multifocal atrial tachycardia (MAT), and ectopic atrial tachycardia (EAT) ().

The increase in HR is associated with greater myocardial oxygen demand and impaired diastolic perfusion. Therefore, the treatment aims to achieve adequate HR control to meet myocardial oxygen demands and prevent potential complications (). This treatment involves the administration of antiarrhythmic agents such as amiodarone, digoxin, and flecainide; however, a lack of response and resistance to these therapies is commonly observed (; ).

1.3 Ivabradine in the pediatric population

Given the lack of effective therapeutic alternatives for treating HF, as well as the frequent resistance to conventional therapies in the case of SVT in pediatric patients, the use of oral ivabradine has been proposed for both conditions.

Currently, ivabradine is approved by the European Medicines Agency (EMA) as an antiarrhythmic agent exclusively for adult patients (). However, while the U.S. Food and Drug Administration (FDA) initially approved ivabradine for use only in adult patients, it later extended its indication to pediatric patients for the treatment of stable symptomatic HF due to DCM from 6 months of age (; ).

Ivabradine has also been used off-label for HR control in pediatric patients with various SVT, such as JET, FAT, MAT, and EAT, demonstrating efficacy and good tolerability (; ; ; ; ). However, the experience with ivabradine in these indications is limited and primarily based on case reports or case series, particularly in patients under 6 months of age, for whom no dosing recommendations have been established.

Thus, data on the efficacy, safety, and dosing of ivabradine in patients younger than 6 months remain very limited. Nevertheless, HF caused by CHD or DCM, as well as SVT, have a higher incidence in this population. This highlights an urgent need for further research on its use in this age group.

The present study aims to evaluate the efficacy and safety of off-label ivabradine use in patients under 6 months of age and to describe the dosing regimens employed.

2 Materials and methods

2.1 Study design and patient selection

Retrospective observational study conducted at a national referral center for both pediatric cardiology and neonatology. The study included all pediatric patients who initiated ivabradine treatment before 6 months of age between January 2020 and May 2024.

Prior to starting ivabradine therapy, as per the hospital’s standard practice, parents or legal guardians were informed about the off-label use of the drug and its potential side effects.

2.2 Data collection

The study was reviewed and approved by the center’s Research Ethics Committee for medicinal products [EOM(AMI)054/2024 (6325)]. After obtaining approval, patients who had received ivabradine treatment within the first 6 months of life during the study period were identified and selected through the electronic prescribing system. The following parameters were collected in an anonymized database (Microsoft Excel® 2016) from the electronic medical records: demographic and clinical variables, indication for ivabradine treatment, variables related to ivabradine use, clinical parameters at the start and end of treatment, and adverse effects.

Patients were classified into two groups based on the indication for ivabradine to evaluate treatment response according to associated clinical variables: i) symptomatic HF: HR and left ventricular ejection fraction (LVEF), and ii) SVT: HR. LVEF was determined via echocardiography using the Teichholz and Simpson methods. The final treatment values of these variables correspond to those recorded at the time of discontinuation or, for patients still receiving therapy, to the latest values measured before the study’s conclusion.

2.3 Compounded formulation of ivabradine

Since ivabradine in Europe is only approved for adult patients, it is commercially available only in tablet form at doses defined for this population, complicating its administration in pediatric patients, especially in those under 6 months of age who require lower doses. Although ivabradine is not classified as a hazardous drug by the U.S. National Institute for Occupational Safety and Health (NIOSH), it could be considered hazardous due to its teratogenic potential, and safety precautions are recommended during its handling ().

To ensure accurate dosing and increase safety during handling, the Pharmacy Department decided to prepare individualized ivabradine capsules for each patient, starting from the commercially available tablet form, using lactose as the excipient.

2.4 Statistical analysis of results

A descriptive statistical analysis was conducted for the demographic and clinical variables of the patients. The results are presented as mean (standard deviation), median (interquartile range), absolute frequencies, and percentages, depending on the nature and distribution of the data.

To evaluate treatment response, the reduction in HR was calculated in both groups, and in the symptomatic HF group, the change in LVEF was also determined. Normality of the variables was assessed graphically and through Skewness/Kurtosis and Shapiro-Wilk tests. If the normality assumption was met, the paired Student’s t-test was used; otherwise, the Wilcoxon signed-rank test was applied. Statistical analysis was performed using StataCorp. 2019 (Stata Statistical Software: Release 16. College Station, TX: StataCorp LLC).

3 Results

During the study period, 13 patients under 6 months of age (nine women) initiated treatment with ivabradine, with a median age of 1.4 (1 - 4) months. Table 1 details the patients diagnosed with symptomatic HF, while Table 2 presents those diagnosed with SVT. Patient 7 is listed in both groups, as she initially received ivabradine for sinus tachycardia and, after completing that treatment, was later diagnosed with severe diastolic dysfunction and resumed ivabradine therapy. Individualized ivabradine capsules were prepared by the Pharmacy Department for all patients included in the study.

TABLE 1

Demographic and clinical variables
Patient 1Patient 2Patient 3Patient 4Patient 5Patient 6Patient 7
SexWWWMMWW
Gestational age at birth (GW)39 + 539 + 126 + 438 + 138 + 239 + 437 + 1
Birth weight (kg)2.73.31.14.12.73.32.7
Medical historySengers syndrome (mitochondrial disease)-MYH7 genetic disorder-Propionic acidemia-Trisomy 21, AV canal heart defect
Baseline variables at the initiation of ivabradine treatment
IndicationCongenital hypertrophic cardiomyopathy with moderate LV dysfunction and mild RV dysfunctionLeft-sided hypoplasia type III with mild RV dysfunction and severe systemic insufficiencyGenetic origin DCM with severe biventricular dysfunctionLeft-sided hypoplasia with mitroaortic atresia, palliated with the Norwood procedure and central shuntLeft-sided DCM with severe dysfunctionCongenital cardiomyopathy with moderate LV dysfunction and mild RV dysfunctionSevere diastolic dysfunction
Age (months)4.42.5430 days3.67 days6.2
Weight (kg)5.44.03.54.23.73.16.5
Time between diagnosis and initiation of treatment (days)1247011128070
Dose (mg/kg/day every 12 h)0.10.10.10.20.050.060.06
Route of administrationNG tubeNG tubeNG tubeNG tubeNG tubeORNG tube
Concomitant treatmentsCaptopril, carvedilolMilrinone, levosimendan, furosemide, digoxinCaptopril, furosemide, carvedilolMilrinone, furosemide, digoxinFurosemideDigoxinCaptopril, furosemide, spironolactone
HR (bpm)150130160160150160140
LVEF (%) Teichholz/Simpson45/5040/NA25/22NA/6430/3045/4879/NA
Variables at the end of ivabradine treatment or at the time of study closure
Discontinuation of treatmentYesYesYesYesYesYesYes
Reason for discontinuation of treatmentPostoperative death following cataract surgeryResolution (subject to various surgical interventions)BradycardiaResolutionResolutionResolutionResolution
Duration of treatment9 days18.5 months13 months8.7 months4.5 months15 days3.7 months
Dose (mg/kg/day every 12 h)0.180.20.20.20.20.10.1
Concomitant treatmentsCaptopril, carvedilolCaptopril, furosemide, digoxinFurosemide, hydrochlorothiazide, digoxinCaptopril, furosemide, digoxinCaptopril, furosemide, spironolactone, carvedilolDigoxinNo
HR (bpm)10012550 - 60115120150120
LVEF (%) Teichholz/SimpsonNA/NA40/NA36/33NA/6552/5247/4383/NA
Related adverse effectsNoNoGastrointestinal, bradycardiaNoQT interval prolongationBradycardiaNo

Patients who received treatment with ivabradine for a diagnosis of symptomatic HF.

AV: atrioventricular; bpm: beats per minute; DCM: dilated cardiomyopathy; GW: gestational weeks; HF: heart failure; HR: heart rate; LV: left ventricular; LVEF: left ventricular ejection fraction; M: man; NA: not available; NG: nasogastric; OR: oral; RV: right ventricular; W: woman.

TABLE 2

Demographic and clinical variables
Patient 8Patient 9Patient 10Patient 11Patient 12Patient 13Patient 7
SexMWWWWMW
Gestational age at birth (GW)41 + 537 + 140 + 037 + 338 + 240 + 337 + 1
Birth weight (kg)NA2.33.73.03.2ND2.7
Medical history---Transposition of the great vessels--Trisomy 21, AV canal heart defect
Baseline variables at the initiation of ivabradine treatment
IndicationCongenital JETFATFATPostoperative anomalous sinus tachycardiaMyocardial ischemia with elevated HRFATPostoperative JET
Age (months)5.120 days30 days9 days1.21.45.7
Weight (kg)7.02.4430103.44.56.9
Time between diagnosis and initiation of treatment (days)533111372
Dose (mg/kg/day every 12 h)0.10.10.10.070.10.10.1
Route of administrationORNG tubeNG tubeNG tubeNG tubeNG tubeOR
Concomitant treatmentsPropranololFurosemide, propranolol, flecainideAmiodaroneMilrinone, furosemide, dopaminePropranololFurosemide, esmolol, flecainideMilrinone, amiodarone, furosemide, spironolactone
HR (bpm)190140175200150180150 - 160
Variables at the end of ivabradine treatment or at the time of study closure
Discontinuation of treatmentNoNoNoYesYesYesYes
Reason for discontinuation of treatment---ResolutionResolutionResolutionResolution
Duration of treatment36 months18.1 months82 days1 dose18.6 months56 days1 day
Dose (mg/kg/day every 12 h)0.40.240.10.070.30.340.1
Concomitant treatmentsPropranololFlecainidePropranololMilrinone, furosemideCaptopril, propranololPropranolol, flecainideFurosemide, spironolactone
HR (bpm)80125125125103119135 - 145
Related adverse effectsNoBradycardiaNoNoSelf-limited bradycardiaNoNo

Patients who received ivabradine treatment for a diagnosis of SVT.

AV: atrioventricular; bpm: beats per minute; FAT: focal atrial tachycardia; GW: gestational weeks; HR: heart rate; JET: junctional ectopic tachycardia; M: man; NA: not available; NG: nasogastric; OR: oral; SVT: supraventricular tachycardia; W: woman.

Table 3 presents the descriptive statistics and statistical analysis of the demographic and clinical variables of patients classified by diagnosis, as well as the results before and after ivabradine treatment.

TABLE 3

Symptomatic HF n = 7SVT n = 7
Demographic and clinical variables
Womenn (%)5 (71)5 (71)
Gestational age at birth (GW)Mean (SD)36.5 (4.5)38.6 (1.6)
Birth weight (kg)Median (range)2.99 (2.7 - 3.33)3.11 (2.67 - 3.2)
Baseline variables at the initiation of ivabradine treatment
Age (months)Median (range)3.6 (1.75 - 4.2)1.2 (0.9 - 3.25)
Weight (kg)Median (range)3.95 (3.62 - 4.82)4 (3.2 - 5.5)
Time between diagnosis and initiation of treatment (days)Median (range)28 (3.5 - 89.5)3 (2.5 - 8)
Dose (mg/kg/day every 12 h)Median (range)0.06 (0.057 - 0.1)0.1 (0.1 - 0.12)
Route of administrationORn (%)1 (14)2 (29)
NG tuben (%)6 (86)5 (71)
Number of concomitant treatmentsMedian (range)3 (1.5 - 3)2 (1 - 3)
HR (bpm)Mean (SD)152.1 (13.5)170.7 (21.7)
LVEF (%)TeichholzMean (SD)44 (19)-
SimpsonMean (SD)42.9 (16.8)-
Variables at the end of ivabradine treatment or at the time of study closure
Discontinuation of treatmentn (%)7 (100)4 (57)
Duration of treatmentMedian (range)4.5 (2.1 - 10.85)2.7 (0.85 - 18.35)
Dose (mg/kg/day every 12 h)Median (range)0.2 (0.14 - 0.2)0.24 (0.12 - 0.32)
Number of concomitant treatmentsMedian (range)3 (1.5 - 3)2 (1 - 2)
HR (bpm)Mean (SD)111.4 (30.9)116 (18.6)
Reduction in HR (bpm)Mean (SD)
P value
−40.7 (36.0) p = 0.04−54.7 (31.8) p = 0.02
LVEF (%)TeichholzMean (SD)51.6 (18.6)-
SimpsonMean (SD)48.3 (13.6)-
Increment in LVEF (%)TeichholzMean (SD); p value7.8 (9); p = 0.12-
SimpsonMean (SD); p value7.3 (11.8); p = 0.38-

Descriptive statistics and analysis of demographic and clinical variables of patients by diagnosis.

bpm: beats per minute; GW: gestational weeks; HF: heart failure; HR: heart rate; LVEF: left ventricular ejection fraction; NG: nasogastric; OR: oral; SD: standard deviation; SVT: supraventricular tachycardia.

None of the patients in the symptomatic HF group continued on ivabradine therapy. In five of the seven patients (71.4%), treatment was discontinued following resolution of dysfunction, with adequate HR control observed in all of them (mean reduction of 41 beats per minute (bpm)) and an improvement in LVEF (mean increase of 7%–8%). Treatment was only discontinued in one patient due to adverse effects (bradycardia). For patients with SVT, treatment was discontinued in four of the seven patients (57.1%) following resolution of the tachyarrhythmia and improvement in HR (mean reduction of 55 bpm), and no discontinuation was required due to adverse effects, although two patients experienced bradycardia during treatment, with one case being self-limiting. In both groups, the reduction in HR was statistically significant.

Regarding the dosing of ivabradine for symptomatic HF, the median starting dose was 0.06 (0.057 - 0.1) mg/kg/day and the maintenance dose was 0.2 (0.14 - 0.2) mg/kg/day. In the case of SVT, the doses were 0.1 (0.1 - 0.12) mg/kg/day for the starting dose and 0.24 (0.12 - 0.32) mg/kg/day for the maintenance dose. The median duration of treatment for patients with symptomatic HF was 4.5 (2.1 - 10.9) months, while for patients with SVT, it was 2.7 (0.9 - 18.35) months.

4 Discussion

Certain cardiac conditions, such as HF and SVT, are associated with high morbidity and mortality in the pediatric population, particularly in patients under 6 months and 1 year of age (; ). Despite the severity of these conditions, treatment evidence is limited due to a lack of studies in pediatrics. This results in restricted pharmacological options and, at times, inadequate disease management due to poor response or resistance to conventional treatments. Consequently, there is a need for the use of off-label therapies and/or those with limited evidence, such as ivabradine.

The mechanism of action of ivabradine is based on the selective and specific inhibition of the cardiac pacemaker current (If), which controls spontaneous diastolic depolarization in the sinus node and regulates HR; this results in a dose-dependent reduction in HR and myocardial oxygen consumption (). Because its cardiac effects are specific to the sinus node, ivabradine exhibits negative inotropic activity, which may present a safer alternative in patients with decompensated systolic HF, compared to beta-blockers (; ). Adverse effects are dose-dependent and arise from its mechanism of action, with frequent side effects including luminous phenomena (phosphenes), bradycardia, atrial fibrillation, headaches, dizziness, blurred vision, and hypotension. Gastrointestinal adverse effects and QT interval prolongation have also been observed ().

However, evidence on the use of ivabradine off-label in the pediatric population is limited and primarily based on case reports or series, particularly in patients younger than 6 months. This poses a significant challenge, as higher prevalence, morbidity, and mortality rates have been reported in this age group.

In this context, the authors find it relevant to share our experience with ivabradine use in patients under 6 months of age to enhance the current evidence regarding its efficacy, safety, and dosing. This also aims to assist other healthcare professionals in its application. To date, this represents the largest published cohort of patients under 6 months receiving ivabradine treatment.

4.1 Ivabradine in HF

The only published clinical trial of ivabradine in pediatric patients was conducted by ; this study included pediatric patients aged 6 months and older with DCM and chronic symptomatic HF. Patients under 6 months of age were excluded due to potential inadequate tolerability with the concomitant administration of two antiarrhythmic drugs. Ivabradine was shown to significantly improve HR, cardiac function, LVEF, and patient quality of life, with an acceptable safety profile. The overall reduction in HR was 21%, and in the subgroup of patients aged six to 12 months, it was 25%. Patients exhibited an increase in LVEF of 11.4% at 6 months of treatment and 13.5% at 12 months. In our cohort of patients with symptomatic HF, a statistically significant reduction in HR was observed, along with an improvement in cardiac function, although the increase in LVEF was smaller. Bradycardia was reported in 11% of patients in the clinical trial, a value comparable to that observed in our cohort (n = 1, 14%).

Most patients in the trial received ivabradine in combination with other pharmacological therapies, including ACEIs, diuretics, beta-blockers, and digoxin. In the present study, all patients started ivabradine in conjunction with other treatments, and only in one case was it possible to discontinue these additional therapies by the end of the ivabradine treatment.

Due to the high interindividual variability observed in treatment response, emphasized the importance of appropriate dose titration. In the subgroup of patients aged six to 12 months (n = 10), an initial dose of 0.02 mg/kg/day every 12 h was established, with dose escalation up to a maximum dose of 0.2 mg/kg/day. In our cohort, the median initial dose used (0.06 mg/kg/day every 12 h) was higher than that reported in the trial, while the maintenance dose was similar (0.2 mg/kg/day every 12 h).

In the literature review conducted, no published cases or series of cases regarding the use of ivabradine in patients under 6 months of age with a diagnosis of HF were found. Therefore, this study is the first to report on the use of ivabradine in this population, making it essential for the authors to share the obtained results. The study demonstrates favorable outcomes regarding the efficacy and safety of ivabradine in this cohort. Additionally, the dosing guidelines used may provide valuable guidance for other healthcare professionals in its application.

4.2 Ivabradine in SVT

The use of ivabradine in pediatric patients with SVT is not well-defined, and current experience is based on case reports and series. The observed results are promising, especially in patients refractory to conventional antiarrhythmics, allowing for complete reversion to sinus rhythm with an acceptable safety profile (; ). Most cases involve patients aged 1 year and older, with evidence for patients under 6 months (; ; ; ; ; ), being even more limited. Table 4 summarizes publications that include patients under 6 months of age who have received ivabradine treatment for various types of SVT.

TABLE 4

References and type of publicationIndicationnAgeAdministration regimenIvabradine dose (mg/kg/day every 12 h)Results
InitialMaintenance
Prospective studyResistant congenital JET510 d - 3.5 y (median: 8 m)Adjuvant therapy0.05 - 0.10.22- Resolution of JET in all patients (restoration to sinus rhythm in four patients)
- No adverse effects

Case series
Congenital JET and secondary multidrug-resistant cardiomyopathy352 d, 2 m, 10 mAdjuvant therapy0.12 patients: 0.1
1 patient: 0.2
- Response within 24 h of initiation
- Complete reversal to sinus rhythm in two patients and partial reversal in one
- No adverse effects

Clinical case
Resistant congenital JET114 dAdjuvant therapy0.10.1- Rapid resolution of tachycardia following initiation
- No adverse effects

Clinical case
Resistant congenital JET126 dAdjuvant therapy0.10.08- Reversion to sinus rhythm after 3 days of treatment
- Bradycardia requiring dose adjustment
- After 6 months of follow-up, adequate control of HR with no adverse effects

Clinical case
Resistant congenital JET112 dAdjuvant therapy0.10.1- Reversion to sinus rhythm and discontinuation of one of the two antiarrhythmic medications
- No adverse effects

Clinical case
Resistant congenital JET1NeonateMonotherapy0.20.2- Reversion to sinus rhythm within 2 h of initiation
- No adverse effects

Prospective study
Resistant postoperative JET71 patient: 5 m
2 patients: 6 m
Adjuvant therapy0.10.1- Time between diagnosis and initiation of treatment: 5–8 h
- Reversion to sinus rhythm within 1–15 h of initiation
- Duration of treatment: 2 doses
- No adverse effects

Retrospective study
Resistant postoperative JET81 patient: 3 d
1 patient: 1 m
2 patients: 2 m
Monotherapy0.10.1- Reversion to sinus rhythm within 3–16 h after initiation
- Duration of treatment: 3–4 doses
- Adequate HR control and reversion to sinus rhythm
- No adverse effects

Case series
Resistant postoperative JET32.5 m, 5 m, 5.6 mAdjuvant therapy0.20.2- Reversion to sinus rhythm within 48–96 h after initiation
- Duration of treatment: 3–4 d
- No adverse effects

Retrospective study
SVT
*79 patients with SVT were included, with ivabradine administered to 3 of them for resistant SVT. Only one patient was <6 months of age
119 dAdjuvant therapy0.050.075- Reversion to sinus rhythm after dose escalation (0.075 mg/kg/day every 12 h) on day 2
- No adverse effects
- Ivabradine appears to be a safe and well-tolerated medication that can induce adequate suppression of SVT, achieve complete reversion to sinus rhythm, and effectively improve left ventricular function

Prospective study
Resistant FAT125 m −15 y (a 5-month-old patient)Monotherapy0.20.4- Reversion to sinus rhythm after 48 h of treatment in 6 patients (including the 5-month-old patient)
- No adverse effects

Retrospective study
TAF in patients with CHD157 m (1–18 m)
(3 patients <3 m)
Adjuvant therapy
11 patients
Monotherapy
4 patients
0.050.07 (0.04–0.16)- First-line treatment in 5 patients
- Reversion to sinus rhythm in 12 patients within the first 24 h after initiation
- Bradycardia in 7 patients

Clinical case
Resistant FAT115 dAdjuvant therapy0.10.1- Reversion to sinus rhythm and discontinuation of 2 out of 4 antiarrhythmic medications after one dose
- No adverse effects

Clinical case
MAT15 mAdjuvant therapy0.050.05- Duration of treatment: 2 doses
- Stabilization and reversion to a single EAT, enabling subsequent ablation and reversion to sinus rhythm
- No adverse effects

Clinical cases
Resistant EAT260 dAdjuvant therapy0.30.3- Reversion to sinus rhythm within 12 h of initiation
- HR control and hemodynamic stability after one dose
- No adverse effects
EAT30 dAdjuvant therapy0.30.3- Early initiation after diagnosis
- Reversion to sinus rhythm within 4 h of initiation
- No adverse effects

Clinical case
Resistant EAT142 dMonotherapy0.050.3- Reversion to sinus rhythm
- Duration: 1 year, currently in the process of discontinuation
- No adverse effects

Publications including patients under 6 months of age who have received ivabradine treatment for a diagnosis of any type of SVT.

CHD: congenital heart disease; d: days; EAT: ectopic atrial tachycardia; HR: heart rate; FAT: focal atrial tachycardia; JET: junctional ectopic tachycardia; m: months; MAT: multifocal atrial tachycardia; SVT: supraventricular tachycardia; y: years.

JET is considered an uncommon SVT, which can be congenital (congenital JET) or post-surgical (post-surgical JET), with the latter being more common (; ; ). Despite its lower incidence, congenital JET is associated with severe cardiovascular complications and high morbidity and mortality, particularly in patients under 6 months of age with elevated heart rates, who have a worse prognosis (; ). To achieve adequate HR control, the administration of at least two antiarrhythmic drugs is typically required, with amiodarone being the treatment of choice (). However, the lack of efficacy of conventional treatments has led to the use of off-label medications such as ivabradine, which, although its experience is limited, has shown favorable results (). Current studies conclude that ivabradine is an effective therapeutic option with a good safety profile for managing resistant congenital JET, providing adequate HR control and complete reversion to sinus rhythm (; ; ; ; ). Additionally, it may reduce the need for combinations of more than two antiarrhythmic drugs and invasive treatments (). While ivabradine is often administered in combination with other antiarrhythmic agents, it has also demonstrated adequate efficacy as monotherapy (). Some authors suggest that early initiation of treatment following diagnosis may be related to the positive response ().

Post-surgical JET is the most common post-surgical arrhythmia that causes hemodynamic instability, and it is associated with significant morbidity and mortality (). One of the risk factors for its development is young age (). Its treatment typically involves intravenous pharmacotherapy with agents such as amiodarone and flecainide (). Similar to congenital JET, ivabradine has shown promising results in terms of efficacy and safety for the treatment of post-surgical JET, both as an adjunctive therapy and as monotherapy, with a notable rapid onset of action (; ; ; ). In this case, studies also recommend early initiation of treatment (; ).

In cases of FAT, MAT, or EAT that are refractory to conventional treatments, off-label use of ivabradine has also yielded results similar to those observed with JET; so, ivabradine may be an effective and safe therapeutic option, either in conjunction with other antiarrhythmic agents or as monotherapy. Additionally, there is a noted association between early initiation of ivabradine and a more rapid reversion to sinus rhythm (; ; ). The only adverse effect reported in the studies has been bradycardia, which underscores the importance of close monitoring ().

Consistent with the reviewed publications, this study observed a statistically significant reduction in HR among patients receiving ivabradine for SVT. Additionally, ivabradine could be withdrawn in four patients (57%) following reversion to sinus rhythm. The median starting dose of ivabradine was 0.1 (0.1 - 0.12) mg/kg/day every 12 h, with a median maintenance dose of 0.24 (0.12 - 0.32) mg/kg/day every 12 h, results comparable to those reported in the literature. The median time from diagnosis to initiation of ivabradine was 3 days, which can be considered an early initiation of treatment, a relevant factor as it may influence the response. The only adverse effect observed in this study was bradycardia in two patients, an event previously reported by other authors, but it did not lead to discontinuation of treatment in any patient. Although the overall median number of concomitant treatments was not reduced, it was possible to discontinue some of the initial therapies in five patients (71%).

4.3 Study limitations

The primary limitations and biases of the study arise from its retrospective nature, such as the lack of data in some cases. However, despite the limited number of patients, this is currently the first published study that includes patients under 6 months of age with symptomatic HF treated with ivabradine and represents the largest cohort of patients under 6 months receiving ivabradine for the diagnosis of SVT.

5 Conclusion

In conclusion, in patients under 6 months of age with symptomatic HF or SVT, ivabradine improved clinical parameters with a satisfactory safety profile and proved to be an effective and safe therapeutic alternative for this patient population.

Statements

Data availability statement

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

Ethics statement

The studies involving humans were approved by Research Ethics Committee for medicinal products (Study code EOM(AMI)054/2024 (6325)) of Vall d’Hebron University Hospital. The studies were conducted in accordance with the local legislation and institutional requirements. Written informed consent for participation in this study was provided by the participants’ legal guardians/next of kin. Written informed consent was obtained from the minor(s)’legal guardian/next of kin for the publication of any potentially identifiable images or data included in this article.

Author contributions

LG-G: Conceptualization, Data curation, Formal Analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing–original draft, Writing–review and editing. CP-T: Conceptualization, Data curation, Formal Analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing–original draft, Writing–review and editing. GG-G: Conceptualization, Data curation, Investigation, Methodology, Supervision, Validation, Writing–original draft, Writing–review and editing. CF-G: Conceptualization, Data curation, Investigation, Methodology, Supervision, Validation, Writing–original draft, Writing–review and editing. QF-M: Conceptualization, Data curation, Investigation, Methodology, Supervision, Validation, Writing–original draft, Writing–review and editing. MC-P: Writing–review and editing, Conceptualization, Formal Analysis, Investigation, Methodology, Project administration, Supervision, Validation, Visualization, Writing–original draft.

Funding

The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article.

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Generative AI statement

The author(s) declare that no Generative AI was used in the creation of this manuscript.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Glossary

  • ACEIs

    Angiotensin-converting enzyme inhibitors

  • AV

    Atrioventricular

  • bpm

    Beats per minute

  • CHD

    Congenital heart diseases

  • d

    Days

  • DCM

    Dilated cardiomyopathy

  • EAT

    Ectopic atrial tachycardia

  • EMA

    European Medicines Agency

  • FAT

    Focal atrial tachycardia

  • FDA

    Food and drug administration

  • GW

    Gestational weeks

  • HF

    Heart failure

  • HR

    Heart rate

  • JET

    Junctional ectopic tachycardia

  • LV

    Left ventricular

  • LVEF

    Left ventricular ejection fraction

  • M

    Man

  • MAT

    Multifocal atrial tachycardia

  • m

    Months

  • NA

    Not available

  • NG

    Nasogastric

  • NIOSH

    National Institute for Occupational Safety and Health

  • OR

    Oral

  • RV

    Right ventricular

  • SD

    Standard deviation

  • SVT

    Supraventricular tachycardias

  • W

    Woman

  • y

    Years

References

Summary

Keywords

heart failure, ivabradine, pediatrics, tachycardia, atrial tachycardia, ectopic atrial tachycardia, supraventricular tachycardia, junctional ectopic tachycardia

Citation

Gómez-Ganda L, Parramón-Teixidó CJ, Giralt-García G, Fernández-García C, Ferrer-Menduiña Q and Cabañas-Poy MJ (2025) Ivabradine in treatment of symptomatic heart failure and supraventricular tachycardias in patients under six months of age. Front. Pharmacol. 16:1502375. doi: 10.3389/fphar.2025.1502375

Received

26 September 2024

Accepted

27 January 2025

Published

18 February 2025

Volume

16 - 2025

Edited by

Tamer M. Mohamed, University of Louisville, United States

Reviewed by

Gabriele De Masi De Luca, University of L'Aquila, Italy

He Jiang, Children’s Hospital of Capital Institute of Pediatrics, China

Updates

Copyright

*Correspondence: C. J. Parramón-Teixidó,

ORCID: L. Gómez-Ganda, orcid.org/0000-0003-2441-8607; C. J. Parramón-Teixidó, orcid.org/0000-0001-8023-3979; G. Giralt-García, orcid.org/0000-0002-8186-7073; C. Fernández-García, orcid.org/0000-0002-1935-1906; Q. Ferrer-Menduiña, orcid.org/0000-0003-3177-4618; M. J. Cabañas-Poy, orcid.org/0000-0003-2724-2715

Disclaimer

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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