This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ECG and Arrhythmia 3, Subject name: Medicine
In a patient with history of recurrent syncope, Holter recording shows QT interval of 680msec. Which disease is suspected in this patient? 
Select and explain. 
A. Long QT syndrome, B. Brugada syndrome, C. Arrhythmogenic RV dysplasia, D. Lev's disease
A: Long QT syndrome
Answer: A: Long QT syndrome 
Explanation: Normal QT interval= 360-440 msec. Option A: QT interval prolonged- predisposes to Torsades de Pointes , so Dx of this is Long QT syndrome. Option B: Channel defect (SCN5A defect) in hea-->depolarization is defective -->defective development of voltage gradient leads to arrhythmia which result in Brugada syndrome. Option C: ARVD is fibrofatty deposition in RV epicardium & in ECG presence of Epsilon wave Option D: Lev's disease characterized by fibrosis in conduction system, so will result in Bradyarrhythmia.