Congenital Long QT Syndrome, Coinciding With Cavitary Mycobacterium avium Lung Infection, Led to Cardiac Arrest

Congenital long QT syndrome is a cardiac disorder leading to arrhythmias and sudden cardiac death. We present a case of a 55-year-old woman with altered mental status experiencing cardiac arrest caused by congenital long QT syndrome, coincidentally found with Mycobacterium avium complex lung infection. Genetic testing identified a pathogenic mutation in the KCNH2 gene. (Level of Difficulty: Intermediate.).