Congenital Long QT Syndrome Unmasked by COVID-19 Infection Presenting as Ventricular Tachycardia Storm

BACKGROUND: Congenital long QT syndrome (LQTS) predisposes to torsades de pointes and sudden cardiac death. Although it usually manifests in childhood or early adulthood, external triggers may unmask the disease later in life. COVID-19 has been associated with cardiovascular complications, but its association with ventricular tachycardia storm precipitated by congenital LQTS is rarely reported. CASE SUMMARY: A woman in her 50s presented with recurrent syncope during acute COVID-19. Electrocardiography showed marked QTc prolongation and torsades de pointes requiring cardioversion, deep sedation, and beta-blocker therapy. She received an implantable cardioverter-defibrillator for secondary prevention and was discharged. Genetic testing later identified a pathogenic KCNQ1 variant, confirming LQT1. DISCUSSION: This case illustrates that COVID-19 can unmask latent congenital LQTS even at a late age, underscoring the importance of QT monitoring and genetic evaluation in patients with unexplained arrhythmias. TAKE-HOME MESSAGES: COVID-19 can unmask latent LQTS and trigger ventricular tachycardia storm, even in midlife. QT monitoring, genetic testing, and guideline-based therapy are essential.