Abstract
<title>Abstract</title> <p> <bold>Introduction</bold> Arrhythmias in the neonatal period are abnormalities of heart rate that carry a significant risk of mortality and morbidity if not diagnosed early. There is limited evidence on the characteristics, frequency and treatment approaches of arrhythmias in the early neonatal period (0-7 days). <bold>Materials and Methods</bold> In this retrospective study, we analyzed the data of 40 patients diagnosed with clinically significant arrhythmias in the early neonatal period between December 2017 and November 2024. Sex, birth weight, clinical signs and symptoms, electrocardiography (ECG), Holter ECG, echocardiography (ECHO) findings, treatment and follow-up outcomes were evaluated. <bold>Results</bold> Clinically significant arrhythmia was detected in 40 (0.97%) of 4126 newborns in the early neonatal period. The median follow-up period was 30.5 months (range, 6–67 months). The most common arrhythmia type was supraventricular tachycardia (SVT) and the most common subtype was atrioventricular reentrant tachycardia (AVRT). In the bradyarrhythmia group, non-conducted premature atrial contractions (non-conducted PACs) and complete atrioventricular (AV) block were detected. Arrhythmia-induced cardiomyopathy was present in eight patients (20%), and congenital heart disease (CHD) was found in five patients (12.5%). Initial treatments included vagal maneuvers, adenosine, amiodarone, and flecainide. One patient died due to heart failure. During the follow-up period, SVT recurrence was observed in four cases, all of whom achieved rhythm control with antiarrhythmic therapy. <bold>Conclusions</bold> Our study emphasizes the importance of early diagnosis and treatment in improving the prognosis of clinically significant arrhythmias in the early neonatal period. Non-conducted PACs can be successfully managed with medical treatment when they cause hemodynamic disturbances. These contractions may lead to clinical conditions requiring early intervention, and appropriate treatment can improve cardiac function. The low recurrence and mortality rates in patients without complex congenital heart disease in our study group suggest that arrhythmias in the early neonatal period may have a favorable prognosis with correct diagnosis and treatment. </p>