Refractory Malignant Arrhythmia in a 4-Year-Old Child With Short QT Syndrome: Persistence for Hope

Short QT syndrome (SQTS) is a rare cardiac channelopathy and can cause malignant arrhythmia and sudden cardiac arrest.

A 4-year-and-6-month-old girl presented with intermittent convulsions and recurrent ventricular fibrillation requiring multiple electrical cardioversions. Electrocardiogram revealed a QTc interval ranging from 294 to 324 milliseconds and polymorphic ventricular tachycardia. Whole-exome sequencing was performed, which revealed no mutations in ion channel-related genes. Quinidine can prolong the QT interval but failed to reduce the occurrence of premature ventricular arrhythmia. Based on the origin site of premature ventricular contractions and literature reports, verapamil and mexiletine were added to the treatment regimen. After the implantation of implantable cardioverter-defibrillator, intermittent ventricular fibrillations still occurred during the 6-month follow-up.

When the use of quinidine alone was insufficient to prevent electrical storms, lidocaine test and electrocardiographic characteristics can help guide drug selection.

In pediatric SQTS, when high-dose quinidine fails to reduce the risk of sudden death, combination therapy with other antiarrhythmic drugs should be considered. Implantable cardioverter-defibrillator implantation remains the most effective method for preventing sudden death in children with SQTS.