Atypical Andersen-Tawil Syndrome in an Asymptomatic Child With Bidirectional Ventricular Tachycardia and Incipient Tachycardiomyopathy.

backgroundBidirectional ventricular tachycardia is a rare electrocardiographic (ECG) finding, associated with a restricted group of clinical conditions, particularly hereditary channelopathies. CASE SUMMARY: An 11-year-old girl, asymptomatic from a cardiovascular point of view, was identified by family screening after detection in her father of a pathogenic variant in the KCNJ2 gene. The admission ECG showed bidirectional ventricular tachycardia. Clinical investigation revealed periodic paralysis and skeletal dysmorphisms, confirming a diagnosis of Andersen-Tawil syndrome. Pharmacological treatment significantly reduced the arrhythmic burden, with reverse ventricular remodeling at follow-up. DISCUSSION: This case illustrates the central role of ECG as a diagnostic tool in rare cardiovascular diseases, allowing early recognition, targeted genetic investigation, and prevention of arrhythmia-induced cardiomyopathy. TAKE HOME MESSAGES: Bidirectional ventricular tachycardia is a distinct ECG pattern that should raise suspicion of Andersen-Tawil syndrome and warrants genetic evaluation with cascade family screening. In this patient, the combination of propafenone and beta-blocker therapy was associated with suppression of bidirectional ventricular tachycardia, significant reduction in ventricular arrhythmic load, and reversal of tachycardiomyopathy, suggesting a potential therapeutic alternative when flecainide is not available.