Diagnostic Evolution From Channelopathy to Idiopathic Ventricular Fibrillation After Aborted Sudden Cardiac Death

BACKGROUND: Idiopathic ventricular fibrillation (IVF) is a life-threatening condition with no identifiable structural or metabolic etiology. It is a diagnosis of exclusion and accounts for a significant proportion of unexplained sudden cardiac death (SCD) in young healthy individuals. CASE SUMMARY: In a 23-year-old woman initially experiencing seizure-like activity, long QT syndrome was later diagnosed. Following placement of an implantable cardioverter-defibrillator, subsequent evaluation, including cardiac magnetic resonance, negative 51-gene arrhythmia panel, and subcutaneous cardiac monitor implantable loop recorder, confirmed the spontaneous episode of ventricular fibrillation. In the absence of a persistent long QT syndrome phenotype, the findings were most consistent with IVF. DISCUSSION: This case underscores the importance of systematic reassessment and high clinical suspicion to establish IVF and guide timely management. TAKE-HOME MESSAGE: IVF is a diagnosis of exclusion requiring comprehensive evaluation and management with implantable defibrillators and antiarrhythmic therapy for preventing recurrent episodes.