Outpatient presentation of ventricular fibrillation in paediatric left ventricular assist device patients: a case series with mechanistic insights

BACKGROUND: Ventricular fibrillation in paediatric recipients of left ventricular assist devices is rare but potentially fatal; however, because systemic perfusion may be temporarily maintained by the mechanical support, haemodynamic deterioration may be delayed, leading to underrecognition and presentation in the outpatient setting rather than as an immediate in-hospital emergency. METHODS: We report three paediatric left ventricular assist device recipients who developed outpatient malignant ventricular arrhythmias, each representing a distinct mechanistic category: structural, mechanical, and endocrine. Clinical presentation, diagnostic findings, and therapeutic responses were reviewed to highlight pathophysiologic heterogeneity and inform individualised management. RESULTS: The first patient, with biopsy-proven arrhythmogenic right ventricular dysplasia, experienced recurrent ventricular fibrillation refractory to multiple antiarrhythmic agents, ultimately requiring heart transplantation. The second patient presented with ventricular fibrillation secondary to mechanical suction and interventricular septal contact; defibrillation and left ventricular assist device speed reduction restored a stable rhythm with no recurrence. The third patient developed polymorphic ventricular arrhythmias during amiodarone-induced thyrotoxicosis and succumbed to refractory electrical storm and multi-organ failure despite intensive endocrine and antiarrhythmic therapy. CONCLUSIONS: Outpatient ventricular fibrillation in paediatric left ventricular assist device recipients may result from diverse mechanisms, including myocardial structural disease, mechanical pump heart interaction, and systemic endocrine disturbances. Mechanism-guided management combining antiarrhythmic, mechanical, and metabolic interventions is essential for optimal outcomes. Continuous rhythm surveillance and readiness for immediate defibrillation are key to improving survival in this vulnerable group.