Clinical Practice and Cases in Emergency Medicine

Introduction: Idiopathic fascicular ventricular tachycardia is a rare form of ventricular tachycardia that is commonly seen in young, otherwise healthy individuals without structural heart disease. This rhythm can be difficult to distinguish from other forms of tachyarrhythmia, including supraventricular tachycardia, yet acute pharmacologic management of this condition varies significantly from more common forms.

Case Report: We describe a 42-year-old woman with no cardiac history who presented with palpitations and lightheadedness. She was found to be in a hemodynamically stable, wide-complex tachycardia. Given no prior cardiac history, supraventricular tachycardia with aberrancy was initially considered as a leading diagnosis; however, a trial of adenosine and lidocaine was ineffective. Her electrocardiogram revealed a regular wide complex tachycardia at 262 beats per minute with a right bundle branch block morphology and right axis deviation, consistent with a rare left anterior fascicular subtype of ventricular tachycardia. She later underwent successful ablation of the left anterior fascicle with no recurrence of symptoms at follow-up.

Conclusion: This report highlights a case of idiopathic fascicular ventricular tachycardia successfully treated with intravenous verapamil and left anterior fascicle ablation, addressing the diagnostic challenges of this arrhythmia. Early recognition by emergency physicians is essential to avoid treatment delays and ensure appropriate definitive management.