Electrical storm induced by premature ventricular beat with extremely short coupling interval in a patient with long QT syndrome type 3.

Here we report the case of a 10-year-old boy with long QT syndrome type 3 (LQT3) who developed refractory torsade de pointes (TdP) associated with ventricular arrhythmia with a short coupling time (VASCT). After implantable cardioverter-defibrillator replacement, an electrical storm occurred, which was irresponsive to the ventricular pacing as high as 120 bpm. Close inspection of the intracardiac potential revealed TdP associated with VASCT. Dexmedetomidine and verapamil were effective in controlling TdP, which allowed management with slower ventricular pace. Our case highlights the importance of focusing on ventricular arrhythmias particularly those with short coupling interval, in LQT3 with refractory TdP. (99 words).