Long QT Syndrome With KCNH2/SCN5A Dual Gene Mutation Leading to Electrical Storm

Long QT syndrome (LQTS) is a genetic ion channel abnormality characterized by a long QT interval and torsades de pointes. Torsades de pointes can progress to ventricular fibrillation and sudden cardiac death, and stressful conditions such as infections can be an acquired trigger of malignant arrhythmias. LQTS due to compound genetic mutations are clinically rare, and its diagnosis and therapy are challenging and require a multidisciplinary comprehensive intervention.

A 62-year-old man presented with malignant arrhythmia and shock, triple-vessel coronary artery disease, dual LQT mutations (KCNH2/LQT2 and SCN5A/LQT3), and Gram-negative sepsis. The arrhythmia was successfully controlled by means of emergency defibrillation, temporary pacing, anti-infective therapy, and ultimately the placement of an implantable cardioverter-defibrillator.

In this patient, the double gene mutations KCNH2 and SCN5A caused LQTS, which caused electrical storm and mixed shock under infectious stress. Based on the electrocardiographic changes, the dynamic evolution of troponin levels, and genetic testing, LQTS was a more plausible etiology than acute coronary syndrome. An integrated multimodal strategy was used: anti-infective therapy, temporary pacing to shorten the QT interval, and implantable cardioverter-defibrillator placement. This case highlights the value of genetic diagnosis of complex arrhythmias and the need for acute-phase trigger control and long-term treatment.

When managing malignant arrhythmias, hereditary channelopathies and infections need to be considered as significant causes. Genetic testing plays an important role in diagnosis, risk assessment, and family management.