A case of congenital type 1 long QT syndrome which developed electrical storm with myocarditis

This case report presents a 39-year-old woman with congenital type 1 long QT syndrome (LQT1) who was transported to the hospital after syncope. She had no previous history of syncope or ventricular fibrillation, but had a family history of LQT1 without sudden death. On arrival, she had regained consciousness with stable vital signs, although she reported cold symptoms starting a week previously. An electrocardiogram showed a prolonged QTc interval of 618 ms, and echocardiography revealed severe left ventricular dysfunction with an ejection fraction (EF) of approximately 15 %. She suddenly developed torsades de pointes and lost consciousness again, progressing to an electrical storm requiring repeated defibrillation. Emergency coronary angiography showed no stenosis, and right heart catheterization revealed hemodynamic parameters consistent with Forrester classification III. A myocardial biopsy from the right ventricular septum was performed due to suspected myocarditis. Treatment included sedation, mechanical ventilation, catecholamines, and intra-aortic balloon pump, stabilizing her hemodynamics. Pathological findings confirmed inflammatory cell infiltration in the myocardium. Her EF returned to normal within approximately two weeks. This report discusses an unusual case of electrical storm in LQT1 triggered by myocarditis, with a full recovery achieved.

This case emphasizes that careful management is required for patients with type 1 long QT (LQT1) syndrome. Despite guideline-based management, this case developed an electrical storm triggered by myocarditis as a cardiac event. This case suggests the need to re-evaluate the implantable cardioverter defibrillator implantation criteria for high-risk LQT1 cases.