Torsades de pointes and myocardial infarction following reversal of supraventricular tachycardia with adenosine: a case report

Adenosine is an antiarrhythmic drug that slows conduction through the atrioventricular node and acts as a coronary blood vessel dilator. This case report highlights two unusual life-threatening events following the use of adenosine to revert supraventricular tachycardia in a structurally normal heart: non-sustained polymorphic ventricular tachycardia and myocardial infarction. A 46-year-old woman presented to the emergency department with a two-hour history of palpitations and was diagnosed with supraventricular tachycardia. Vagal maneuvers were ineffective, and after intravenous adenosine administration, the patient presented with chest pain and hypotension. The rhythm degenerated into non-sustained polymorphic ventricular tachycardia and spontaneously reverted to sinus rhythm with ST elevation in lead aVR and ST depression in the inferior and anterolateral leads. The patient spontaneously recovered within a few minutes. Despite successful arrhythmia reversal, the patient was admitted to the intensive care unit because of an infarction without obstructive atherosclerosis. This report aims to alert emergency physicians about the potential complications associated with supraventricular tachycardia and its reversal with adenosine.

Rationale and design of the NODE-303 study: evaluating the safety of symptom-prompted, self-administered etripamil for paroxysmal supraventricular tachycardia episodes in real-world settings

BACKGROUND

Paroxysmal supraventricular tachycardia (PSVT) is a common episodic arrhythmia characterized by unpredictable onset and burdensome symptoms including palpitations, dizziness, chest pain, distress, and shortness of breath. Treatment of acute episodes of PSVT in the clinical setting consists of intravenous adenosine, beta-blockers, and calcium channel blockers (CCBs). Etripamil is an intranasally self-administered L-type CCB in development for acute treatment of AV-nodal dependent PSVT in a nonmedical supervised setting.

METHODS

This paper summarizes the rationale and study design of NODE-303 that will assess the efficacy and safety of etripamil. In the randomized, double-blinded, placebo-controlled, Phase 3 RAPID trial, etripamil was superior to placebo in the conversion of single PSVT episodes by 30 minutes post initial dose when administered in the nonhealthcare setting; this study required a mandatory and observed test dosing prior to randomization. The primary objective of NODE-303 is to evaluate the safety of symptom-prompted, self-administered etripamil for multiple PSVT episodes in real-world settings, without the need for test dosing prior to first use during PSVT. Secondary endpoints include efficacy and disease burden. Upon perceiving a PSVT episode, the patient applies an electrocardiographic monitor, performs a vagal maneuver, and, if the vagal maneuver is unsuccessful, self-administers etripamil 70 mg, with an optional repeat dose if symptoms do not resolve within 10 minutes after the first dose. A patient may treat up to four PSVT episodes during the study. Adverse events are recorded as treatment-emergent if they occur within 24 hours after the administration of etripamil.

RESULTS

Efficacy endpoints include time to conversion to sinus rhythm within 30 and 60 minutes after etripamil administration, and the proportion of patients who convert at 3, 5, 10, 20, 30, and 60 minutes. Patient-reported outcomes are captured by the Brief Illness Perception Questionnaire, the Cardiac Anxiety Questionnaire, the Short Form Health Survey 36, the Treatment Satisfaction Questionnaire for Medication and a PSVT survey.

CONCLUSIONS

Overall, these data will support the development of a potentially paradigm-changing long-term management strategy for recurrent PSVT.

Combined modified Valsalva maneuver with adenosine supraventricular tachycardia: A comparative study

BACKGROUND AND IMPORTANCE

Paroxysmal supraventricular tachycardia (PSVT) is an arrhythmia commonly seen in the emergency department. Both modified Valsalva maneuver (MVM) and intravenous adenosine are the first line treatment, of which the former has e lower success rate while the latter has a higher success rate but some risks and adverse effects. Given both of these reverse rhythms quickly, combining them may achieve a better effect.

OBJECTIVE

The objective of this study is to evaluate the success rate and potential risk of combining the use of intravenous adenosine while patients were doing MVM as a treatment for paroxysmal supraventricular tachycardia(pSVT).

DESIGN, SETTINGS AND PARTICIPANTS

We recruited patients with pSVT from 2017 to 2022, and randomly assigned them into 3 groups, MVM group, intravenous adenosine group, and combination therapy group, in which MVM was allowed to be performed twice, while intravenous adenosine was given in a titration manner to repeat three times, recorded the success rate and side effects in each group.

MAIN RESULTS

The success rate of the MVM group, adenosine group, and combination group are 42.11%, 75.00 and 86.11%, respectively. The success rate of the adenosine group and combination group is significantly higher than the n MVSM group (p < 0.01, p < 0.001), while the success rate of the combination group is higher than the adenosine group, it has no significant difference (p = 0.340). In terms of safety, the longest RR durations (asystole period) are 1.61 s, 1.60s, and 2.27 s, there is a statistical difference among the three groups (p < 0.01) and between the adenosine and combination group (0.018).

CONCLUSION

Therefore, we can conclude that combination therapy has a relatively high success rate and good safety profile, but the current study failed to show its superiority to adenosine.

Drugs associated with a risk of supraventricular tachycardia: analysis using the OpenVigil database

OBJECTIVE

The OpenVigil database can be used to assess medications that may cause supraventricular tachycardia (SVT) and to produce a reference for their safe use in clinical settings.

METHODS

We analyzed first-quarter data from 2004 to 2023, obtained by searching the OpenVigil database using the keyword "supraventricular tachycardia." Trade names and generic names were obtained by querying the RxNav database, and the proportions were summarized. The proportionate reporting ratio (PRR), reporting odds ratio, and chi-square values were also summarized. We created Asahi diagrams and set the screening criteria to drug events ≥30, PRR >2, and chi-square >4. Outcomes were evaluated using the Side Effect Resource database, several scientific literature databases, and the Hangzhou Yiyao Rational Medication System.

RESULTS

A total of 2435 distinct medications were found to induce SVT between the first quarter of 2004 and 2023, leading to 22,375 documented adverse events related to SVT. Further investigation revealed that salbutamol, paroxetine, formoterol, paclitaxel, venlafaxine, and theophylline were most likely to cause SVT.

CONCLUSION

We conducted signal mining of adverse drug events using the OpenVigil database and evaluated the six drugs most likely to cause SVT. The results of this research can serve as a drug safety reference in the clinic.

Impact of dexmedetomidine on electrophysiological properties and arrhythmia inducibility in adult patients referred for reentrant supraventricular tachycardia ablation

BACKGROUND

Drugs used for sedation/analgesia may affect the basic cardiac electrophysiologic properties or even supraventricular tachycardia (SVT) inducibility. Dexmedetomidine (DEX) is a selective alpha-2 adrenergic agonist with sedative and analgesic properties. A comprehensive evaluation on use of DEX for reentrant SVT ablation in adults is lacking. The present study aims to systematically assess the impact of DEX on cardiac electrophysiology and SVT inducibility.

METHODS

Hemodynamic, electrocardiographic, and electrophysiological parameters and SVT inducibility were assessed before and after DEX infusion in patients scheduled for ablation of reentrant SVT.

RESULTS

The population of this prospective observational study included 55 patients (mean age of 58.7 ± 14 years, 29 males [52.7%]). A decrease in systolic and diastolic blood pressure and in heart rate was observed after DEX infusion (p = 0.001 for all). DEX increased corrected sinus node refractory time, atrial effective refractory period, AH interval, AV Wenckebach cycle length, and AV node effective refractory period without affecting the His-Purkinje conduction or ventricular myocardium refractoriness. No AV blocks or sinus arrests occurred during DEX infusion. Globally, there was no difference in SVT inducibility in basal condition or after DEX infusion (46/55 [83.6%] vs. 43/55 [78.1%] patients; p = 0.55), without a difference in isoprenaline use (p = 1.0). In 4 (7.3%) cases, the SVT was inducible only after DEX infusion. In 34.5% of cases, DEX infusion unmasked the presence of an obstructive sleeping respiratory pattern, represented mainly by snoring.

CONCLUSIONS

DEX depresses sinus node function and prolongs atrioventricular refractoriness without significantly affecting the rate of SVT inducibility in patients scheduled for reentrant SVT ablation.

Refractory supraventricular fetal tachycardia as a cause of non-immune hydrops: management conundrum

Supraventricular tachyarrhythmia (SVT) is the most common form of fetal tachyarrhythmias. The presentation can vary from ill-defined, non-sustained episodes of tachyarrhythmia to frank non-immune hydrops. The standard of care is transplacental therapy by treating the mother with oral antiarrhythmic drugs, followed by direct fetal therapy in refractory cases. We report a case of primigravida in her late 20s, who presented at 28.1 weeks of gestation with fetal hydrops and SVT. She was initially managed with oral digoxin and flecainide, but due to worsening hydrops, risk of fetal demise and extreme prematurity, further management by direct fetal therapy was given in terms of intramuscular digoxin and intraperitoneal flecainide. Following which, the fetus had a favourable outcome. This case highlights the possible role of direct fetal therapy in refractory cases of SVT.

Rediscover the predictive capacity of B-type natriuretic peptide applied to neonatal supraventricular tachycardia

BACKGROUND

Supraventricular tachycardia (SVT) is one of the most common non-benign arrhythmias in neonates, potentially leading to cardiac decompensation. This study investigated the early risk factors of acute heart failure (AHF) secondary to SVT in neonates, and explored their value in guiding the selection of effective anti-arrhythmic treatment.

METHODS

A total of 43 newborns diagnosed with and treated for SVT between January 2017 and December 2022 were analyzed. According to the presence of AHF after restoring sinus rhythm in newborns with SVT, they were divided into SVT with AHF group and SVT without AHF group. Clinical data and anti-arrhythmic therapies were analyzed. Risk factors of AHF secondary to SVT in neonates were determined using logistic regression. The cut-off value for predictors of AHF secondary to SVT and demanding of a second-line anti-arrhythmic treatment was determined through receiver operating characteristic (ROC) analysis.

RESULTS

Time to initial control of tachycardia > 24 h, hyperkalemia, anemia, and plasma B-type natriuretic peptide (BNP) were identified as risk factors of AHF secondary to SVT in neonates. BNP exhibited AUC of 0.80 in predicting AHF, and BNP > 2460.5pg/ml (OR 2.28, 95% CI 1.27 ~ 45.39, P = 0.03) was an independent predictor, yielding sensitivity of 70.6% and specificity of 84.6%. Neonates with BNP > 2460.5pg/ml (37.5% versus 7.4%, P = 0.04) had a higher demand for a second line anti-arrhythmic treatment to terminate SVT, with sensitivity and specificity for BNP in predicting at 75.0%, 71.4%, respectively.

CONCLUSIONS

BNP could be used to predict an incident of AHF secondary to SVT and a demand of second-line anti-arrhythmic treatment to promptly terminate SVT and prevent decompensation in neonates.

Patient Characteristics Associated with Hospital Admission or Antiarrhythmic Medication Changes After Emergency Department Evaluation of Supraventricular Tachycardia

BACKGROUND

Supraventricular tachycardia (SVT) is a relatively frequent diagnosis in the pediatric emergency department (ED). However, there are no consensus guidelines for ED disposition, and there are limited data on ED outcomes. Better understanding of those who are admitted or have antiarrhythmic medication changes may avoid potentially unnecessary transfers or admissions. Our objective was to identify patient factors associated with discharge from the emergency department without medication initiation or modification after management of SVT in the pediatric ED.

DESIGN/METHODS

A retrospective review of children aged 0-18 years seen in the emergency department for SVT was conducted using electronic medical record data over a ten-year period at a single academic tertiary children's hospital. Patients with congenital cardiac disease or prior cardiac surgeries were excluded. Multivariable logistic regression analysis was used to determine association between patient factors of interest and the primary outcome of admission and secondary outcome of change to antiarrhythmic medications.

RESULTS

We analyzed 197 patients encounters. The mean age was 7 years. Of these 104 (52.8%) were admitted to the hospital or discharged with antiarrhythmic medication changes. This primary outcome was associated with younger age (aOR 0.77, 95% CI 0.67-0.86), history of pre-excitation (aOR 5.82, 95% CI 2.01-18.8), intercurrent illness (aOR 3.75, 95% CI 1.27-12.1), number of adenosine doses prior to arrival (aOR 5.45, 95% CI 1.55-22.3), and in-person cardiology consultation (aOR 6.42, 95% CI 2.43-19.4).

CONCLUSIONS

Nearly half of children treated in a pediatric ED for SVT are discharged without changes in medications. We identified patient factors associated with hospital admission or antiarrhythmic medication changes. These factors represent high value care and can be assessed when considering transfer from a referring facility. Risk stratification using these patient characteristics may reduce potentially avoidable transfers and admissions.

Management of acute supraventricular tachycardia in children

QUESTION

Recently, a 3-year-old patient in my practice urgently needed to go to the emergency department. The patient was found to have supraventricular tachycardia (SVT) and needed immediate treatment with adenosine. What evidence is currently available for management of SVT in children?

ANSWER

Supraventricular tachycardia is a common cardiac condition in the pediatric population that manifests as a narrow QRS complex tachycardia on electrocardiography. Symptoms may range from palpitations, poor feeding, and irritability to more substantial hemodynamic instability. Patients who are hemodynamically stable can benefit from interventions such as vagal maneuvers, which can be done in the office. Such maneuvers include the Valsalva maneuver, stimulation of the diving reflex (for infants), and unilateral carotid sinus massage. Other children may need pharmacologic therapies to restore normal heart rhythm, which usually consists of a rapid intravenous injection of adenosine under monitoring. For patients who are hemodynamically unstable, emergency cardioversion may be needed.

Effect of different dose regimens of everolimus in a series of neonates with giant cardiac rhabdomyomas

Everolimus is a mTOR inhibitor that has been increasingly used in high-risk cardiac rhabdomyomas in recent years. There are questions regarding the optimal dose and duration of therapy with everolimus for cardiac rhabdomyomas. The purpose of this study was to examine retrospectively the dosage-efficacy relationship in seven babies diagnosed with rhabdomyoma treated with different everolimus dose regimens retrospectively. Cardiac rhabdomyoma diagnosis was made in six of seven babies during the prenatal period. Indication of everolimus was an obstruction in six patients and supraventricular tachycardia which is resistant to antiarrhythmic drugs in the remaining one patient. The median age was 8 days (range; 2-105 days) at the time of starting everolimus. It was administered at a dose of 0.25 mg twice a day for two days a week in four patients; 0.1 mg/day in two and 0.4 mg/day in one patient. Serum everolimus level was kept between 5 and 15 ng/ml. All seven cases showed significant regression of cardiac rhabdomyoma within four weeks, and supraventricular tachycardia was controlled in two weeks after everolimus administration.This study demonstrates that everolimus was effective in accelerating regression of the cardiac rhabdomyoma. Dose with 2 × 0,25 mg/day, 2 days a week, seems appropriate. However, lower doses such as 0.1 mg/day are also effective. But dose adjustment should be made according to serum level monitoring.

Etripamil Nasal Spray for Conversion of Repeated Spontaneous Episodes of Paroxysmal Supraventricular Tachycardia During Long-Term Follow-Up: Results From the NODE-302 Study

Background Self-administration of investigational intranasal L-type calcium channel blocker etripamil during paroxysmal supraventricular tachycardia (PSVT) appeared safe and well-tolerated in the phase 3 NODE-301 (Multi-Centre, Randomized, Double-Blind, Placebo-Controlled, Efficacy, and Safety Study of Etripamil Nasal Spray for the Termination of Spontaneous Episodes of Paroxysmal Supraventricular Tachycardia) trial of adults with sustained atrioventricular nodal-dependent PSVT. The NODE-302 open-label extension further characterized etripamil safety and efficacy. Methods and Results Eligible patients were monitored via self-applied cardiac monitoring system for 5 hours after etripamil self-administration. The primary end point was time-to-conversion of positively adjudicated PSVT to sinus rhythm after etripamil treatment. Probability of conversion to sinus rhythm was reported via Kaplan-Meier plot. Adverse events were based on self-reported symptoms and clinical evaluations. Among 169 patients enrolled, 105 self-administered etripamil ≥1 time for perceived PSVT (median [range], 232 [8-584] days' follow-up). Probability of conversion within 30 minutes of etripamil was 60.2% (median time to conversion, 15.5 minutes) among 188 PSVT episodes (92 patients) positively adjudicated as atrioventricular nodal dependent by independent ECG analysis. Among 40 patients who self-treated 2 episodes, 75% had a significantly consistent response by 30 minutes; 9 did not convert on either episode, and 21 converted on both episodes (χ2=8.09; P=0.0045). Forty-five of 105 patients (42.9%) had ≥1 treatment-emergent adverse event, generally transient and mild-to-moderate, including nasal congestion (14.3%), nasal discomfort (14.3%), or rhinorrhea (12.4%). No serious cardiac safety events were observed within 24 hours of etripamil. Conclusions In this extension study, investigational etripamil nasal spray was well tolerated for self-treating recurrent episodes of PSVT without medical supervision. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03635996.

Adenosine response and failure to convert paroxysmal supraventricular tachycardia in the emergency department

BACKGROUND AND IMPORTANCE

Although adenosine is the recommended first-line therapy for patients with paroxysmal supraventricular tachycardia (SVT), it may fail to restore normal sinus rhythm. The factors associated with this failure remain unclear.

OBJECTIVE

To assess the response rate to adenosine and identify the factors causing adenosine failure in the management of paroxysmal SVT.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective study was conducted on adult patients diagnosed with paroxysmal SVT and treated with adenosine in the emergency departments of two large tertiary hospitals between June 2015 and June 2021.

OUTCOME MEASURE AND ANALYSIS

The primary outcome of the study was the patient response to adenosine, defined as the restoration of sinus rhythm documented in the patients' files. Backward-stepwise multivariate logistic regression was used to examine the predictors of adenosine failure based on the overall response to adenosine therapy.

MAIN RESULTS

A total of 404 patients, with a mean age of 49 (SD 15) years and a BMI of 32 (SD 8) kg/m 2 , and treated with adenosine for paroxysmal SVT, were included. Sixty-nine percent of patients were women. The overall response rate to any adenosine dose was 86% (n = 347). The baseline heart rate did not significantly differ between adenosine responders and non-responders (179.6 ± 23.1 vs. 183.2 ± 23.4). An association was observed between the history of paroxysmal SVT and successful response to adenosine (odds ratio = 2.08; 95% confidence interval 1.05-4.11).

CONCLUSION

The findings of this retrospective study suggested that the use of adenosine restored normal sinus rhythm in 86% of patients with paroxysmal SVT. Furthermore, a history of paroxysmal SVT and older age were associated with an increased chance of adenosine success.

Treatment, not delivery, of the late preterm and term fetus with supraventricular arrhythmia

OBJECTIVE

While in-utero treatment of sustained fetal supraventricular arrhythmia (SVA) is standard practice in the previable and preterm fetus, data are limited on best practice for late preterm (34 + 0 to 36 + 6 weeks), early term (37 + 0 to 38 + 6 weeks) and term (> 39 weeks) fetuses with SVA. We reviewed the delivery and postnatal outcomes of fetuses at ≥ 35 weeks of gestation undergoing treatment rather than immediate delivery.

METHODS

This was a retrospective case series of fetuses presenting at ≥ 35 weeks of gestation with sustained SVA and treated transplacentally at six institutions between 2012 and 2022. Data were collected on gestational age at presentation and delivery, SVA diagnosis (short ventriculoatrial (VA) tachycardia, long VA tachycardia or atrial flutter), type of antiarrhythmic medication used, interval between treatment and conversion to sinus rhythm and postnatal SVA recurrence.

RESULTS

Overall, 37 fetuses presented at a median gestational age of 35.7 (range, 35.0-39.7) weeks with short VA tachycardia (n = 20), long VA tachycardia (n = 7) or atrial flutter (n = 10). Four (11%) fetuses were hydropic. In-utero treatment led to restoration of sinus rhythm in 35 (95%) fetuses at a median of 2 (range, 1-17) days; this included three of the four fetuses with hydrops. Antiarrhythmic medications included flecainide (n = 11), digoxin (n = 7), sotalol (n = 11) and dual therapy (n = 8). Neonates were liveborn at 36-41 weeks via spontaneous vaginal delivery (23/37 (62%)) or Cesarean delivery (14/37 (38%)). Cesarean delivery was indicated for fetal SVA in two fetuses, atrial ectopy or sinus bradycardia in three fetuses and obstetric reasons in nine fetuses that were in sinus rhythm at the time of delivery. Twenty-one (57%) cases were treated for recurrent SVA after birth.

CONCLUSION

In-utero treatment of the near term and term (≥ 35-week) SVA fetus is highly successful even in the presence of hydrops, with the majority of cases delivered vaginally closer to term, thereby avoiding unnecessary Cesarean section. © 2023 International Society of Ultrasound in Obstetrics and Gynecology.

Maturity makes sense: managing supraventricular tachyarrhythmia in the late preterm and term fetus

Linked article: This Editorial comments on Holmes et al. Click here to view the article.

Termination of paroxysmal supraventricular tachycardia by intranasal swab insertion

Paroxysmal supraventricular tachycardia (SVT) is a common emergency department presentation. Vagal maneuvers are commonly tried to terminate SVT but are often unsuccessful in terminating the dysrhythmia. The use of adenosine, while often successful, is associated with a number of side effects and is often disliked by patients with recurrent episodes of SVT. We report on a 44-year-old woman with a past medical history of SVT who presented to the emergency department (ED) due to a recurrence of her SVT. The patient had no intravenous access and preferred not to receive adenosine. The patient received intranasal stimulation with a nasopharyngeal swab used for COVID-19 testing for 5-10 s. After less than 10 s, the patient converted to a sinus rhythm. She was successfully discharged from the ED after 1 h of observation and no recurrence of her SVT.

Etripamil Nasal Spray: Therapeutic Potential for Treating Paroxysmal Supraventricular Tachycardia

Patients with arrythmias are at an increased risk of heart-related comorbidities and complications. Specifically, patients with paroxysmal supraventricular tachycardia (PSVT), a type of arrythmia, are at increased risk of lightheadedness or shortness of breath, due to the increased rate of the heartbeat. Most patients are prescribed oral medications to control their heart rates and maintain a normal heart rhythm. Researchers have been tasked with discovering alternative treatment options with new delivery methods to treat arrythmias such as PSVT. A nasal spray was subsequently designed and is currently undergoing clinical studies. This review aims to present and discuss the current clinical and scientific evidence pertaining to etripamil.

Self-administered intranasal etripamil using a symptom-prompted, repeat-dose regimen for atrioventricular-nodal-dependent supraventricular tachycardia (RAPID): a multicentre, randomised trial

BACKGROUND

Etripamil is a fast-acting, intranasally administered calcium-channel blocker in development for on-demand therapy outside a health-care setting for paroxysmal supraventricular tachycardia. We aimed to evaluate the efficacy and safety of etripamil 70 mg nasal spray using a symptom-prompted, repeat-dose regimen for acute conversion of atrioventricular-nodal-dependent paroxysmal supraventricular tachycardia to sinus rhythm within 30 min.

METHODS

RAPID was a multicentre, randomised, placebo-controlled, event-driven trial, conducted at 160 sites in North America and Europe as part 2 of the NODE-301 study. Eligible patients were aged at least 18 years and had a history of paroxysmal supraventricular tachycardia with sustained, symptomatic episodes (≥20 min) as documented by electrocardiogram. Patients were administered two test doses of intranasal etripamil (each 70 mg, 10 min apart) during sinus rhythm; those who tolerated the test doses were randomly assigned (1:1) using an interactive response technology system to receive either etripamil or placebo. Prompted by symptoms of paroxysmal supraventricular tachycardia, patients self-administered a first dose of intranasal 70 mg etripamil or placebo and, if symptoms persisted beyond 10 min, a repeat dose. Continuously recorded electrocardiographic data were adjudicated, by individuals masked to patient assignment, for the primary endpoint of time to conversion of paroxysmal supraventricular tachycardia to sinus rhythm for at least 30 s within 30 min after the first dose, which was measured in all patients who administered blinded study drug for a confirmed atrioventricular-nodal-dependent event. Safety outcomes were assessed in all patients who self-administered blinded study drug for an episode of perceived paroxysmal supraventricular tachycardia. This trial is registered at ClinicalTrials.gov, NCT03464019, and is complete.

FINDINGS

Between Oct 13, 2020, and July 20, 2022, among 692 patients randomly assigned, 184 (99 from the etripamil group and 85 from the placebo group) self-administered study drug for atrioventricular-nodal-dependent paroxysmal supraventricular tachycardia, with diagnosis and timing confirmed. Kaplan-Meier estimates of conversion rates by 30 min were 64% (63/99) with etripamil and 31% (26/85) with placebo (hazard ratio 2·62; 95% CI 1·66-4·15; p<0·0001). Median time to conversion was 17·2 min (95% CI 13·4-26·5) with the etripamil regimen versus 53·5 min (38·7-87·3) with placebo. Prespecified sensitivity analyses of the primary assessment were conducted to test robustness, yielding supporting results. Treatment-emergent adverse events occurred in 68 (50%) of 99 patients treated with etripamil and 12 (11%) of 85 patients in the placebo group, most of which were located at the administration site and were mild or moderate, and all of which were transient and resolved without intervention. Adverse events occurring in at least 5% of patients treated with etripamil were nasal discomfort (23%), nasal congestion (13%), and rhinorrhea (9%). No serious etripamil-related adverse events or deaths were reported.

INTERPRETATION

Using a symptom-prompted, self-administered, initial and optional-repeat-dosing regimen, intranasal etripamil was well tolerated, safe, and superior to placebo for the rapid conversion of atrioventricular-nodal-dependent paroxysmal supraventricular tachycardia to sinus rhythm. This approach could empower patients to treat paroxysmal supraventricular tachycardia themselves outside of a health-care setting, and has the potential to reduce the need for additional medical interventions, such as intravenous medications given in an acute-care setting.

FUNDING

Milestone Pharmaceuticals.

Sotalol in neonates for arrhythmias: Dosing, safety, and efficacy

INTRODUCTION

Various agents may be utilized to manage supraventricular tachycardia (SVT) in neonates and infants. Recently, sotalol has piqued interest given its reported success in managing neonates and infants with SVTs, especially with the intravenous formulation. While the manufacturer recommends using an age-related nomogram in neonates and young infants to guide doses, clinical reports describe various dosing based on weight (mg/kg) or on body surface area (BSA) in mg/m2 . Given the reported variation in clinical practice with regard to dosing in neonates, there is a gap in the literature and translation into clinical practice regarding applicability of the nomogram into clinical practice. The purpose of this study was to describe sotalol doses based on body weight and BSA in neonates for SVT.

METHODS

This is a single center retrospective study evaluating effective sotalol dosing from January 2011 and June 2021 (inclusive). Neonates who received intravenous (IV) or oral (PO) sotalol for SVT were eligible for inclusion. The primary outcome was to describe sotalol doses based on body weight and BSA. Secondary outcomes include comparison of doses to the manufacturer nomogram, description of dose titrations, reported adverse outcomes, and change in therapy. Two-sided Wilcoxon signed-rank tests were used to determine statistically significant differences.

RESULTS

Thirty-one eligible patients were included in this study. The median (range) age and weight were 16.5 (1-28) days and 3.2 (1.8-4.9) kg, respectively. The median initial dose was 7.3 (1.9-10.8) mg/kg or 114.3 (30.9-166.7) mg/m2 /day. Fourteen (45.2%) of patients required a dose increase for SVT control. The median dose required for rhythm control was 8.5 (2-14.8) mg/kg/day or 120.7 (30.9-225) mg/m2 /day. Of note, the median recommended dose per manufacturer nomogram for our patients would have been 51.3 (16.2-73.8) mg/m2 /day, which is significantly lower than both the initial dose (p < .001) and final doses (p < .001) utilized in our study. A total of 7 (22.9%) patients were uncontrolled on sotalol monotherapy using our dosing regimen. Two patients (6.5%) had reports of hypotension and one patient (3.3%) had a report of bradycardia requiring discontinuation of therapy. The average change in baseline QTC following sotalol initiation was 6.8%. Twenty-seven (87.1%), 3 (9.7%), 1 (3.3%) experienced prolongation, no change, or a decrease in QTc, respectively.

CONCLUSIONS

This study demonstrates that a sotalol strategy significantly higher than the manufacture dose recommendations are required for rhythm control in neonates with SVT. There were few adverse events reported with this dosing. Further prospective studies would be advantageous to confirm these findings.

Assessing the Risk of Hypoglycemia Secondary to Propranolol Therapy for the Treatment of Supraventricular Tachycardia in Infants

Supraventricular tachycardia (SVT) is the most common arrhythmia among infants. Prevention of SVT is frequently managed through propranolol therapy. Hypoglycemia is a known adverse effect of propranolol therapy, but little research has been done on the incidence and risk of hypoglycemia in treatment of SVT in infants with propranolol. This study attempts to offer insight into the risk of hypoglycemia associated with propranolol therapy when treating infantile SVT to help inform future glucose screening guidelines. We conducted a retrospective chart review of infants treated with propranolol in our hospital system. Inclusion criteria were infants < 1 year of age who received propranolol for the treatment of SVT. A total of 63 patients were identified. Data was collected on sex, age, race, diagnosis, gestational age, nutrition source (Total Parenteral Nutrition (TPN) vs oral), weight (kg), weight for length (kg/cm), propranolol dose (mg/kg/day), comorbidities, and whether or not a hypoglycemic event was identified (< 60 mg/dL). Hypoglycemic events were identified in 9/63 (14.3%) patients. Of the patients with hypoglycemic events, 9/9 (88.9%) had comorbid conditions. Patients with hypoglycemic events had significantly lower weight and propranolol dose than those without hypoglycemic events. Weight for length also tended to increase risk for hypoglycemic events. The high incidence of comorbid conditions in the patients who had hypoglycemic events suggests that hypoglycemic monitoring may only be necessary in patients with conditions predisposing to hypoglycemia.

Multicenter cohort study on duration of antiarrhythmic medication for supraventricular tachycardia in infants

Antiarrhythmic medication (AM) is commonly used to prevent supraventricular tachycardia (SVT) recurrence in infants. Our aim was to determine whether a shorter duration of AM is sufficient to prevent atrioventricular reentrant tachycardia (AVRT) recurrence and evaluate risk factors for recurrence of SVT after discontinued AM.This multicenter cohort study included all infants diagnosed with SVT in the five university hospitals in Finland between 2005 and 2017. Those diagnosed between 2005 and 2012 received AM for 12 months (group 1), and those diagnosed between 2013 and 2017 received AM for 6 months (group 2). A total of 278 infants presented with AVRT (group 1, n = 181; group 2, n = 97), and the median AM duration was 12.0 months (interquartile range [IQR] 11.4-13.4) and 7.0 months (IQR 6.0-10.2), respectively. Propranolol was the most frequently used first-line AM (92% and 95%). Recurrence-free survival rates were over 88% until 12 months after AM prophylaxis in both groups, without any statistically significant difference between them. Independent risk factors for recurrence of SVT after discontinuation of AM were need of combination AM (HR 2.2, 95% CI 1.14-4.20), Wolff-Parkinson-White (WPW) syndrome (HR 2.4, 95% CI 1.25-4.59), and age over 1 month at admission (HR 2.2, 95% CI 1.12-4.48).    Conclusion: Shortening AM duration in infants from 12 to 6 months does not seem to lead to more frequent SVT recurrence. The risk factors for recurrence of SVT were WPW syndrome, need of combination AM, and age over 1 month.

When Adenosine Does Not Work: Apparent and Real Adenosine-Resistant Tachycardia

ABSTRACT

Supraventricular tachycardia (SVT) is the most common arrhythmia in the pediatric population. Adenosine is widely accepted as the first-line pharmacological treatment for hemodynamically stable SVT, constituting a class I recommendation in the 2020 American Heart Association guidelines for pediatric life support (2020 American Heart Association Guidelines for cardiopulmonary resuscitation and emergency cardiovascular care). As most pediatric SVTs are dependent on the atrioventricular node (AVN) for their propagation, and adenosine acts primarily on the AVN, adenosine will frequently terminate the arrhythmia. The term "adenosine failure" is often used to describe when its administration does not result in sustained termination of the tachycardia. Because of its very short half-life, there is confusion between improper delivery, failure to have any effect on the tachycardia, or transient termination. There are some pediatric SVTs, which are not AVN dependent, and which truly are refractory to adenosine. Simultaneous electrocardiogram recording during administration can provide important information to differentiate between adenosine resistance and transient adenosine effect, thus guiding further management.

Report of a patient with refractory atrial tachycardia whose heart rate was controlled using ivabradine

Ivabradine is an effective treatment for focal atrial tachycardia. However, it may also be effective for re-entrant atrial arrhythmia. An 85-year-old woman with a history of underlying ischaemic cardiomyopathy complained of worsening symptoms of heart failure because of rapid atrial tachycardia that was resistant to several rate-controlling drugs, but responded well to ivabradine. An electrophysiology study demonstrated a roof-dependent macro-re-entrant tachycardia of the left atrium. Linear ablation of the left atrial roof resulted in termination of the tachycardia. Thus, ivabradine can be an effective treatment for re-entrant atrial tachycardia.

Fetal Supraventricular Tachycardia: What the Adult Cardiologist Needs to Know

Fetal supraventricular tachycardia management is challenging, with consequences for both the fetus and the mother. If left untreated, fetal hydrops may ensue, at which point delivery and treatment of the arrhythmia is preferred. However, if the fetus is not at term nor near-term, significant doses of antiarrhythmics may be needed to achieve adequate transplacental bioavailability. Although digoxin has classically been the mainstay of treatment, the use of flecainide or sotalol as monotherapy or in combination with digoxin is being studied. Interdisciplinary team management and shared decision-making between the physician and patient are key to achieving successful outcomes. Adult cardiologists, particularly inpatient consultation services or through burgeoning cardio-obstetrics programs, may, in some practice settings, be asked to evaluate or comanage pregnant women with fetal arrhythmia.

Perioperative Management of Flecainide: A Problem-Based Learning Discussion

Flecainide is a first-line antiarrhythmic drug used to treat atrial arrhythmias and/or supraventricular tachycardia in those without coronary artery disease or structural heart disease. Even though it is an older antiarrhythmic, flecainide accounted for 1.6 million prescriptions in the United States in 2016, and its utilization is generally increasing. Despite its popularity, flecainide may predispose patients to rapid atrial flutter with resultant hemodynamic compromise, particularly in the physiologically stressful perioperative period. This article reviews the pharmacology of flecainide, describes problematic arrhythmias that may arise specifically during flecainide use, and offers recommendations for perioperative flecainide management.

Multiple antiarrhythmic transplacental treatments for fetal supraventricular tachyarrhythmia: A protocol for systematic review and meta analysis

BACKGROUND

Fetal supraventricular tachyarrhythmia is a common reason for referral to fetal cardiology. Multiple antiarrhythmic transplacental medications can be used to treat these diseases. Debates remain regarding the standardized therapy.

METHODS

PubMed, EMBASE, Cochrane Library, Web of Science, Google Scholar, and ClinicalTrials.gov will be searched from inception to September 2020. A handsearching for gray literature, including unpublished conference articles, will be performed. The randomized control trials, case-control, and cohort studies will be accepted, no matter what the languages they were reported. We will first focus on the effectiveness of the therapy on fetal cardiac rhythm and/or heart rate. Then we will do further analysis of preterm delivery, fetal hydrops, intrauterine fetal demise, and maternal side effects. The Cochrane Risk of Bias Tool and the Newcastle-Ottawa scale will be used to assess the risk of bias of the randomized controlled trials, case-control, and cohort studies, respectively. Two independent reviewers will carry out literature identification, data collection, and study quality assessment. Discrepancies will be resolved by a third reviewer. Statistical analysis will be conducted using the STATA 13.0 software.

RESULT

The results will provide helpful information about the effect of multiple antiarrhythmic transplacental therapies in pregnancies with supraventricular tachycardia or atrial flutter, and demonstrate which therapy is more effective.

CONCLUSION

The conclusion drawn from this systematic review will benefit the patients with fetal supraventricular tachyarrhythmia.

Neonatal Arrhythmia

Arrhythmias are seldom observed in the newborn period and rarely lead to serious consequences. Because they may be a continuation of fetal arrhythmias, newborn arrhythmias are different from those occurring at later ages. Here we describe a case of a newborn presented with tachycardia at birth. A female baby of 1950 grams born by emergency cesarean section for fetal distress at 36 weeks of gestation. Fetal tachycardia of 251 bpm was detected prenatally. Electrocardiography showed supraventricular tachycardia (SVT). Hematological and biochemical tests done were within normal limits. Echocardiography revealed normal anatomy with severe tachycardia, dilated chambers with moderate to severe TR with moderately reduced ventricle function. For persisting SVT intravenous adenosine was administered with no significant decrease in heart rate, then continuous intravenous amiodarone infusion was started resulting in a transient decrease in heart rate, however again increased, hence baby was started on intravenous digoxin which responded well. Repeated echocardiography showed normal cardiac chambers and function. Baby was discharged on maintenance oral digoxin and was gradually weaned and stopped after 12 months of age. Neonatal arrhythmias is not an uncommon condition in newborns, however it should be early recognized and evaluated for a better outcome of the baby. Although the frequency of arrhythmias in the newborn period is not high, SVT are the most frequently observed arrhythmias in this period.

Resolution of Fetal Hydrops Dependent on Sustained Fetal Supraventricular Tachycardia after Digoxin Therapy

We present a special case of fetal supraventricular tachycardia detected at 34 weeks gestation. Fetal hydrops was noted on ultrasound upon admission. Normal fetal heart rate was maintained for three weeks by maternal administration of digoxin. A live infant was delivered via caesarian section at 37 weeks gestation. This clinical case demonstrated that pharmacological treatment can be effective and helps to prolong pregnancy safely.

Sotalol as an effective adjunct therapy in the management of supraventricular tachycardia induced fetal hydrops fetalis

Sustained fetal supraventricular tachycardia (SVT) complicated by hydrops fetalis carries a significant risk of morbidity and mortality. While there is no clear consensus on first- and second-line therapy options for the management of fetal SVT with or without hydrops fetalis, there exists significant nonrandomized experience with a number of antiarrhythmic agents that has founded the basis for management. Furthermore, recently published meta-analyses and ongoing multicenter prospective studies have aimed to bridge the gap in the literature. We report two cases of sustained fetal SVT with severe secondary hydrops fetalis managed successfully with flecainide-sotalol combination therapy in one case and sotalol-digoxin combination therapy in the second and review the literature for the management of fetal SVT.

Successful intraosseous adenosine administration in a newborn infant with supraventricular tachycardia

BACKGROUND

Supraventricular tachycardia (SVT) is the most common type of tachycardia in childhood. The incidence is 1-4/1000 in childhood and 0.6/1000 in newborns.

CASE

Here we report a 28-day-old male newborn who was diagnosed SVT, admitted to the Pediatric Emergency Department after restlessness that had started three hours before admission and measurement of the heart rate was above 250 beats/min.

CONCLUSIONS

This case is presented in order to emphasize that SVT is rare in the neonatal period and SVT is successfully terminated with the administration of intraosseous adenosine.

[Drug-induced ventricular dissynchrony and tachycardiomyopathy in a newborn]

Ventricular dysfunction secondary to electrical and mechanical dyssynchrony in chronic right ventricular apical pacing is a well-recognized complication. There are no previous reports of pharmacologically induced dyssynchrony. A 10-day old infant with incessant supraventricular tachycardia was admitted to the neonatal intensive care unit. Therapy with oral propranolol was initiated and due to persistence of tachycardia intravenous amiodarone was administered. The patient remained predominantly in tachycardia with heart rates between 200-290 beats per minute for a week with serial echocardiograms showing preserved ventricular function. Oral flecainide was started. After 24 hours of treatment the patient developed a slower incessant wide QRS with a left bundle branch block pattern. The echocardiogram showed deterioration of left ventricular systolic function and moderate mitral regurgitation. Flecainide and propranolol were discontinued. The QRS complex narrowed and despite intermittent breakthroughs of supraventricular tachycardia, ventricular function normalized. Propranolol was restarted to achieve definitive control of the tachycardia. The presence of ventricular dyssynchrony generated by the left bundle branch block pattern secondary to pharmacological treatment with flecainide is a novel possible explanation for the development of ventricular dysfunction.

Efficacy and safety of 1C class antiarrhythmic agent (propafenone) for supraventricular arrhythmias in septic shock compared to amiodarone: protocol of a prospective randomised double-blind study

INTRODUCTION

Supraventricular arrhythmias contribute to haemodynamic compromise in septic shock. A retrospective study generated the hypothesis that propafenone could be more effective than amiodarone in achieving and maintaining sinus rhythm (SR). Certain echocardiographic parameters may predict a successful cardioversion and help in the decision on rhythm or rate control strategy.

METHODS AND ANALYSIS

The trial includes septic shock patients with new-onset arrhythmia, but without severe impairment of the left ventricular ejection fraction. After baseline echocardiography, the patient is randomised to receive a bolus and maintenance dose of either amiodarone or propafenone. The primary outcome is the proportion of patients that have achieved rhythm control at 24 hours after the start of the infusion. The secondary outcomes are the percentages of patients that needed rescue treatments (DC cardioversion or unblinding and crossover of the antiarrhythmics), the recurrence of arrhythmias, intensive care unit mortality, 28-day and 1-year mortality. In the posthoc analysis, we separately assess subgroups of patients with pulmonary hypertension and right ventricular dysfunction. In the exploratory part of the study, we assess whether the presence of a transmitral diastolic A wave and its higher velocity-time integral is predictive for the sustainability of mechanical SR and whether the indexed left atrial endsystolic volume is predictive of recurrent arrhythmia. Considering that the restoration of SR within 24 hours occurred in 74% of the amiodarone-treated patients and in 89% of the patients treated with propafenone, we plan to include 200 patients to have an 80% chance to demonstrate the superiority of propafenone at p=0.05.

ETHICS AND DISSEMINATION

The trial is recruiting patients according to its second protocol version approved by the University Hospital Ethical Board on the 6 October 2017 (No. 1691/16S-IV). The results will be disseminated through peer reviewed publications and conference presentations.

TRIAL REGISTRATION NUMBER

NCT03029169.

Fascicular tachycardia in infancy and the use of verapamil: a case series and literature review

OBJECTIVE

Guidelines state that verapamil is contraindicated in infants. This is based on reports of cardiovascular collapse and even death after rapid intravenous administration of verapamil in infants with supraventricular tachycardia (SVT). We wish to challenge this contraindication for the specific indication of verapamil sensitive ventricular tachycardia (VSVT) in infants.

DESIGN

Retrospective case series and critical literature review.

SETTING

Hospitals within New Zealand.

PATIENTS

We present a series of three infants/young children with VSVT or 'fascicular VT'.

RESULTS

Three children aged between 8 days and 2 years presented with tachycardia 200-220 beats per minute with right bundle brunch block and superior axis. Adenosine failed to cardiovert and specialist review diagnosed VSVT. There were no features of cardiovascular shock. Verapamil was given as a slow infusion over 10-30 min (rather than as a push) and each successfully cardioverted without incident. Critical review of the literature reveals that cardiovascular collapses were associated with a rapid intravenous push in cardiovascularly compromised infants and/or infants given other long-acting antiarrhythmics prior to verapamil.

CONCLUSIONS

Verapamil is specifically indicated for the treatment of fascicular VT, and for this indication should be used in infancy, as well as in older children, as first-line treatment or after failure of adenosine raises suspicion of the diagnosis. We outline how to distinguish this tachycardia from SVT and propose a strategy for the safe intravenous slow infusion of verapamil in children, noting that extreme caution is necessary with pre-existing ventricular dysfunction.

Fetal supraventricular tachycardia at 12 weeks of gestation: diagnosis and follow up. A case report

This report describes a case of fetal supraventricular tachycardia (SVT) diagnosed at 12 weeks of gestation in a pregnant woman with diabetes mellitus. Transplacental digoxin therapy administered orally to the mother was unsuccessful. Subsequently, sotalol was added to digoxin to achieve fetal heart rate (HR) control and the conversion to sinus rhythm was achieved. The fetal HR remained stable until term, and a healthy male baby was born. The newborn electrocardiogram showed sinus rhythm with normal PR and QTc intervals. When the newborn was stable, he was discharged with propanolol. Sustained SVT is extremely rare during the first trimester. The goal of treatment in utero is the conversion to sinus rhythm or reduction of the ventricular rate to tolerable levels, preventing or even reversing fetal hydrops.

[Regulatory adaptive status in determining the effectiveness of bisoprololum and sotalolum in patients with hypertensive disease and paroxysmal supraventricular tachycardia]

AIM

To determine efficacy of bisoprolol and sotalol treatments in patients with paroxysmal supraventricular tachycardia (SVT) and essential hypertension (EH) considering effects of these treatments on the regulatory adaptive status (RAS).

MATERIALS AND METHODS

The study included 49 patients with paroxysmal SVT associated with stage II-III EH randomized to two groups of either bisoprolol (6.9±2.2 mg/day, n=25) or sotalol (162.5±46.2 mg/day, n=24) treatment. Lisinopril (14.5±3.9 and 14.3±4.7 mg/day) and, if indicated, atorvastatin (15.4±3.8 mg/day, n=9 and 16.0±4.8 mg/day, n=10), and acetylsalicylic acid (91.5±14.7 mg/day, n=12 and 94.1±16.5 mg/day, n=14) were administered as a part of combination therapy. Quantitative evaluation of RAS (cardiorespiratory synchronism test), EchoCG, triplex scanning of brachiocephalic arteries, treadmill test, 6-min walk test, 24-h BP and ECG monitoring, and subjective assessment of the quality of life were performed at baseline and after 6 months of therapy.

RESULTS

Both regimens of the combination drug therapy comparably improved the structural and functional status of the heart, increased exercise tolerance, effectively suppressed SVT paroxysms, and improved the quality of life. In this process, sotalol reduced RAS to a lesser extent that bisoprolol.

CONCLUSION

In patients with paroxysmal SVT associated with stage II-III EH, the sotalol treatment as a part of the combination therapy may be preferable due to fewer adverse effects on RAS compared to bisoprolol.

Etripamil Nasal Spray for Rapid Conversion of Supraventricular Tachycardia to Sinus Rhythm

BACKGROUND

There is no nonparenteral medication for the rapid termination of paroxysmal supraventricular tachycardia.

OBJECTIVES

The purpose of this study was to assess the efficacy and safety of etripamil nasal spray, a short-acting calcium-channel blocker, for the rapid termination of paroxysmal supraventricular tachycardia (SVT).

METHODS

This phase 2 study was performed during electrophysiological testing in patients with previously documented SVT who were induced into SVT prior to undergoing a catheter ablation. Patients in sustained SVT for 5 min received either placebo or 1 of 4 doses of active compound. The primary endpoint was the SVT conversion rate within 15 min of study drug administration. Secondary endpoints included time to conversion and adverse events.

RESULTS

One hundred four patients were dosed. Conversion rates from SVT to sinus rhythm were between 65% and 95% in the etripamil nasal spray groups and 35% in the placebo group; the differences were statistically significant (Pearson chi-square test) in the 3 highest active compound dose groups versus placebo. In patients who converted, the median time to conversion with etripamil was <3 min. Adverse events were mostly related to the intranasal route of administration or local irritation. Reductions in blood pressure occurred predominantly in the highest etripamil dose.

CONCLUSIONS

Etripamil nasal spray rapidly terminated induced SVT with a high conversion rate. The safety and efficacy results of this study provide guidance for etripamil dose selection for future studies involving self-administration of this new intranasal calcium-channel blocker in a real-world setting for the termination of SVT. (Efficacy and Safety of Intranasal MSP-2017 [Etripamil] for the Conversion of PSVT to Sinus Rhythm [NODE-1]; NCT02296190).

Usefulness of Routine Transtelephonic Monitoring for Supraventricular Tachycardia in Infants

OBJECTIVE

We hypothesize that routine daily transtelephonic monitoring (TTM) transmissions can accurately detect supraventricular tachycardia (SVT) in asymptomatic infants and/or assuage parental concerns rather than being used solely to diagnose arrhythmias.

STUDY DESIGN

Single center, retrospective chart review of 60 patients with fetal or infant SVT prescribed TTM for at least 30 days, January 2010-September 2016. Patients were excluded if initial SVT was not documented, was perioperative, was atrial flutter/fibrillation, or chaotic atrial tachycardia. Categorical variables expressed as mean ± SD. Mann-Whitney, Spearman correlation, and Fisher exact tests were used for continuous and categorical variables respectively.

RESULTS

Sixty patients were included. There were 2688 TTM transmissions received from 55 of 60 patients over 61.1 ± 66.7 days (0.73 ± 0.65 TTM/patient/days). Routine asymptomatic TTM transmissions revealed actionable findings in 5 of 2801 TTM transmissions sent by 5 patients (8.3%). No patient presented in shock or died. Forty-five of 2688 TTM transmissions were sent for parental concerns/symptoms in 16 patients (25.8%) with findings of normal sinus rhythm in 37 of 45 TTM transmissions and SVT in 8 of 45 TTM transmissions. Symptomatic actionable findings were more likely sent by patients discharged on class I or III antiarrhythmics (95% CI = 11.5%-68.3%, P = .004) and patients with prolonged initial hospitalizations (95% CI = 6.98%-59.7%, P = .01). Flecainide was discontinued in 1 patient after widened QRS was noted on routine TTM.

CONCLUSIONS

TTM accurately diagnose asymptomatic recurrent SVT in neonates and infants before they develop signs of congestive heart failure or shock and is helpful for recurrent SVT management.