Dear Editor,

We read with great interest the article by Lenarczyk et al. on arrhythmic mitral valve prolapse in children and adolescents, which provides much-needed paediatric data in a field largely informed by adult cohorts. ^{Reference Lenarczyk, Tyc, Lenarczyk, Tomasiczek-Santana, Grochowina-Major and Fiszer1} Their work is timely, as risk markers for arrhythmic mitral valve prolapse and sudden cardiac death have been predominantly extrapolated from adult studies with differing disease duration, comorbidities, and arrhythmic substrate. ^{Reference Kahles, Ruckbeil and Mertens2}

In their cohort of 12,955 hospitalised paediatric patients, mitral valve prolapse was identified in 52 children, of whom 13 met criteria for arrhythmic mitral valve prolapse. ^{Reference Lenarczyk, Tyc, Lenarczyk, Tomasiczek-Santana, Grochowina-Major and Fiszer1} Notably, many children exhibited adult-defined high-risk phenotypes such as bileaflet prolapse, mitral annular disjunction, and complex ventricular ectopy yet the observed short-term incidence of sustained ventricular arrhythmia or sudden cardiac arrest was low. ^{Reference Lenarczyk, Tyc, Lenarczyk, Tomasiczek-Santana, Grochowina-Major and Fiszer1,Reference Kahles, Ruckbeil and Mertens2} This apparent dissociation between structural or electrocardiographic risk markers and near-term malignant outcomes underscores the need for age-specific interpretation of these findings.

We contend that simply transplanting adult risk markers to children may be misleading and potentially harmful. ^{Reference Kahles, Ruckbeil and Mertens2,Reference Briceño, Liang and Shirai3} Arrhythmic mitral valve prolapse appears to be a progressive condition in which myxomatous degeneration, papillary muscle fibrosis, and annular disjunction develop over years, with malignant electrical instability emerging later in the disease course. ^{Reference Briceño, Liang and Shirai3,Reference Wright, Dwyer, Wahi and Marwick4} Children may therefore manifest early anatomical features without yet having the fibrotic substrate, myocardial stretch, or chronic mechanical stress necessary to sustain polymorphic ventricular tachycardia or ventricular fibrillation. ^{Reference Briceño, Liang and Shirai3,Reference Wright, Dwyer, Wahi and Marwick4}

Clinically, these findings argue for a balanced strategy that avoids both overtreatment and complacency. It would be inappropriate to adopt adult thresholds for primary-prevention implantable cardioverter-defibrillators in asymptomatic children with mitral valve prolapse and isolated phenotypic risk markers, given the device-related complications, psychosocial burden, and uncertainty about absolute risk in this age group. ^{Reference Law, Lal and Chen5} Equally, children with syncope, complex ventricular ectopy, or a family history of sudden cardiac death warrant systematic evaluation and structured follow-up rather than reassurance based solely on short-term outcome data. ^{Reference Lenarczyk, Tyc, Lenarczyk, Tomasiczek-Santana, Grochowina-Major and Fiszer1,Reference Law, Lal and Chen5} Long-term rhythm surveillance using periodic Holter monitoring, exercise testing, and in selected high-risk cases implantable loop recorders may help define individual arrhythmic trajectories during growth and early adulthood ^{Reference Briceño, Liang and Shirai3,Reference Law, Lal and Chen5}

We therefore support the authors’ implication that paediatric arrhythmic mitral valve prolapse should be conceptualised as a distinct entity rather than a smaller version of adult disease. ^{Reference Lenarczyk, Tyc, Lenarczyk, Tomasiczek-Santana, Grochowina-Major and Fiszer1,Reference Kahles, Ruckbeil and Mertens2} Multicentre, longitudinal paediatric studies with systematic imaging, electrocardiography, ambulatory monitoring, and, where feasible, cardiac magnetic resonance with late gadolinium enhancement are urgently needed to map the evolution from benign prolapse to potentially malignant phenotype. ^{Reference Briceño, Liang and Shirai3} Such collaborative efforts will be essential to derive child-specific risk stratification models that integrate structural, electrical, and family history variables and to define evidence-based thresholds for intensified surveillance and prophylactic therapies. ^{Reference Wright, Dwyer, Wahi and Marwick4,Reference Law, Lal and Chen5} By highlighting the discrepancy between adult risk markers and short-term outcomes in children, Lenarczyk et al. provide an important foundation for this necessary reappraisal of paediatric arrhythmic mitral valve prolapse. ^{Reference Lenarczyk, Tyc, Lenarczyk, Tomasiczek-Santana, Grochowina-Major and Fiszer1}