Arrhythmic mitral valve prolapse is a rare yet potentially fatal syndrome. Recently, high-risk markers for malignant arrhythmias have been identified in adults with mitral valve prolapse, and a risk stratification scheme has been proposed. Little is known about the prevalence of arrhythmic mitral valve prolapse, the characteristics of the syndrome, and risk markers in children and young adults.

A database of a high-volume, tertiary congenital heart defects department was searched to identify all patients with MVP between 2018 and 2025 (8 years). Patients’ characteristics, including arrhythmic risk factors, AMVP diagnosis, and last survival, were noted.

Of 12,955 hospitalised patients, 52 were diagnosed with mitral valve prolapse (0.4%; median age 14y [IQR 6], 35% male). Arrhythmic mitral valve prolapse was diagnosed in 13 patients (25% of the mitral valve prolapse cohort). Phenotypic risk factors were highly prevalent (88.5%), but in the crosstab analysis, only an enlarged left atrium was associated with high-risk arrhythmic events (p = 0.0432). Furthermore, patients with arrhythmic events were significantly older (median 16y) than those without (median 13y; p = 0.019). One patient (2.7%, with concomitant LQTS2) presented with unstable ventricular tachycardia and received an ICD. During a median follow-up of 3 years (IQR 1–4.5), all 52 patients were alive.

One in 250 patients admitted to a tertiary invasive paediatric cardiology department has mitral valve prolapse. Among those with mitral valve prolapse, 1 in 4 presents with arrhythmic mitral valve prolapse. Although risk factors are common, outcomes among young arrhythmic mitral valve prolapse patients appear good. Overlapping with primary electrical disease may flag a worse prognosis. Identification of new risk factors for children is warranted.