Ivabradine Use in a Pediatric Heart Transplant Recipient with Refractory Atrial Tachycardia

Abstract

<h3>Introduction</h3> Ivabradine, an oral I_f channel antagonist, has been used in pediatric and adult heart failure patients for heart rate control, and in adult heart transplant (HT) recipients with sinus tachycardia secondary to cardiac graft denervation. There are little data describing the use of ivabradine in pediatric HT patients. We describe the use of ivabradine in a pediatric HT recipient with refractory ectopic atrial tachycardia (EAT) causing hemodynamic instability. <h3>Case Report</h3> A 3 year old male underwent HT for restrictive cardiomyopathy. Post-transplant course was complicated by pulmonary hypertensive crisis and cardiac arrest, followed by the development of EAT at a rate of >200 bpm and periods of atrial flutter 2 weeks post-transplant. Steroids were started for suspected clinical rejection, but endomyocardial biopsy was reassuring (ACR grade 1R/1A, pAMR0). Hypotension was noted when EAT rate was >170 bpm. Patient was refractory to esmolol, sotalol, and amiodarone. He underwent EP study with ablation of a posterolateral atrial focus, with recurrence of EAT several hours later. Given ongoing hemodynamic instability with EAT, repeat ablation was performed 1 week later with termination of EAT. However, periodic EAT recurred 3 weeks later and he was again symptomatic with recurrent emesis with rates >170 bpm. Ivabradine 0.05 mg/kg twice daily was initiated. After a single dose, the duration and frequency of EAT periods decreased. Rhythm was mostly sinus (SR) with a rate of 90-100 bpm with premature atrial contractions (PACs), few atrial couplets and blocked PACs. No hypotension, bradycardia, or hemodynamic instability was noted. He was discharged home and dose was up-titrated as an outpatient to 0.2 mg/kg twice daily. Six weeks later, a 72 hour Holter monitor showed predominately SR with short bursts of EAT with variable AV conduction, atrial ectopy overall making up <10% of beats, and rare premature ventricular contractions (PVCs). All subsequent clinic ECGs with follow up to 3 months demonstrated SR. Repeat Holter 3 months after initiation of ivabradine showed SR with rare, isolated PACs and PVCs with no EAT. <h3>Summary</h3> Ivabradine can be considered for EAT treatment in pediatric patients post-HT, with no identified side effects.