Idiopathic fascicular left ventricular tachycardia in an anatomically normal heart is a unique entity, in which management and prognosis differ from ventricular tachycardia associated with structural heart diseases. Here we report a case of a 14-year-old girl with idiopathic fascicular left ventricular tachycardia mimicking ventricular tachycardia due to dilated cardiomyopathy.?Case:?A 14-year-old girl presented to the ER with exertional dyspnea and palpitation. BP and HR were 85/65 mmHg, 160bpm. Wide QRS VT with RBBB and left superior axis deviation were observed in ECG. There was cardiomegaly in chest x-ray (Fig.1). Lab findings were as follows: CPK 88U/L (＜170) CK-MB 1.8 ng/ml (＜3.61) Troponin-T 0.01 ng/ml (0-0.014) NT-pro BNP 1908 pg/ml (0-125). Echocardiography revealed that global dilatation of LV and LA EF＝10% (LVDD/LVSD 60/55 mm, Septum/PW 8.7/9.3 mm) (Fig.1). Cardiac arrest was occurred due to pulseless VT. It was failed to stop it. ECMO insertion was started. One week later, ECG rhythm was turned into the normal sinus rhythm, followed by verapamil infusion (Fig.2). The patient was referred to electrophysiology study right after weaning off ECMO. Intracardiac mapping showed fascicular VT originating from left ventricular posterior fascicles. For several follow-ups, function of the heart was improved with EF 41% (LVDD/LVSD 48/34mm, Septum/PW 9.5/9mm) (Fig.3).Conclusions:?We report a unusual case of a 14-year-old girl who had idiopathic fascicular left ventricular tachycardia mimicking ventricular tachycardia due to DCMP.