P0411 - Supraventricular Tachycardia Without Preexcitation as a Cause of Cardiac Arrest

Background: Supraventricular tachycardia (SVT) without the presence of ventricular preexcitation in pediatric patients with a structurally normal heart is generally considered a benign condition. However, in children with fast atrioventricular nodal (AVN) conduction, SVT can be rapid and potentially life threatening.

Objective: We report cases in which cardiac arrest was the first manifestation of SVT.

Methods: This is a single center retrospective review. Patients less than 21 years of age that presented to our institution with resuscitated cardiac arrest and survived to hospital discharge from January 2009 to July 2019 were reviewed. Data was collected on patients’ demographics, cardiac diagnosis and electrophysiology study (EPS) findings, if it was performed. The prevalence of supraventricular tachycardia in patients with an unclear diagnosis who presented with cardiac arrest was determined.

Results: Of the 44 patients that presented with resuscitated cardiac arrest, there were 36 patients (82%) with a diagnosis known to have a risk of life-threatening arrhythmias (8 hypertrophic cardiomyopathy, 7 other cardiomyopathy, 6 cathecolaminergic polymorphic ventricular tachycardia, 5 long QT syndrome, 4 congenital heart disease and 6 others). Of the remaining 8 patients (18%) without a clear diagnosis, 3 (37%) were found to have SVT after the initial presentation. One 13 y/o male with a concealed left sided pathway (Heart rate (HR) in SVT: 260 bpm under sedation), a 15 y/o male with ectopic atrial tachycardia (HR: 240 bpm) and a 13 y/o female with typical AVN reentry tachycardia (HR: 230 bpm on a beta-blocker). Two patients had an ICD implant after presentation prior to the ablation. All underwent a successful ablation of the arrhythmia substrate. These 3 patients represent 0.7% of all patients that underwent an ablation (n=412) during the same period for AVN reentry tachycardia, concealed accessory pathways or ectopic atrial tachycardia.

Conclusion: Although non-preexcited SVT usually has a benign prognosis, there are some patients in which cardiac arrest could be a manifestation. Patients that present with an aborted cardiac arrest of unknown etiology should undergo electrophysiologic testing to elicit occult arrhythmia substrates.