Cardiac arrhythmias in the pediatric population represent both diagnostic and therapeutic challenges due to their heterogeneous etiologies, age-dependent clinical presentations, and the variety of management strategies required. Although many electrophysiological mechanisms are shared with adults, several arrhythmias are unique to infancy and adolescence or are associated with congenital heart disease and inherited channelopathies. Clinical presentation varies considerably with age and may be unclear or nonspecific, especially in neonates and infants. In some cases, arrhythmias are benign and self-limiting; in others, they may represent the earliest manifestation of an underlying cardiac disorder, potentially progressing to hemodynamic instability, serious arrhythmic events, or sudden cardiac death. Recent advancements in electrophysiology, catheter ablation, and device technology have broadened the therapeutic landscape, improving outcomes even in neonatal and infant patients. This review aims to summarize current knowledge on pediatric arrhythmias, with a focus on clinical recognition, diagnostic evaluation, and personalized treatment strategies.

Myocardial hypertrophy (MH) represents a complex and heterogeneous condition in the pediatric and young adult population. While rare in children, MH encompasses a wide spectrum of physiological and pathological entities, ranging from transient hypertrophy in the infants of diabetic mothers to progressive genetic hypertrophic cardiomyopathies (HCM) with significant morbidity and mortality. Differential diagnosis is critical, as many phenocopies—including metabolic, mitochondrial, and syndromic diseases—can mimic HCM. Echocardiography remains the first-line imaging modality, with cardiac magnetic resonance (CMR) and molecular diagnostics increasingly used for detailed characterization. Risk stratification tools, such as the HCM Risk-Kids model, support clinical decision-making but must be integrated with individualized assessment. Advances in prenatal screening and genetic testing have significantly improved outcomes, though long-term management requires multidisciplinary care. Understanding age-specific presentations and the underlying etiologies is essential for accurate diagnosis and targeted treatment. This review provides a comprehensive overview of cardiac hypertrophy from fetal life through young adulthood, with a focus on etiologies, diagnostic approaches, imaging modalities, and therapeutic strategies, and aims to guide clinicians through the evolving landscape of MH, emphasizing early recognition, comprehensive evaluation, and personalized care.