ABCC9 Associated Symptomatic Advanced Atrioventricular Block in a Patient with Significant Family History of Sudden Cardiac Death: A Case Report

Sudden cardiac arrest (SCA) and its consequence sudden cardiac death (SCD) are the common cardiac pathway for death. Often, the cause is not found and the inability to delineate the underlying process presents a major public health challenge. Although CAD represents the most common cause of SCD, arrhythmias are an important cause of the same as these patients present with fewer premonitory symptoms and often go undetected. Inherited arrhythmia syndromes represent a challenge due to limited availability of widespread genetic testing and known pathogenic genetic mutations. One such gene is ABCC9 gene, which encodes the SUR2 subunit of the ATP sensitive potassium channel or KATP channel. Mutations in KATP channel are associated with wide range of inherited diseases. Gain-of-function mutations are associated with Cantu syndrome characterized by hypertrichosis and acromegaloid facial features. Loss-of-function mutations are associated with Brugada syndrome and dilated cardiomyopathy. Here, we report a patient with a likely pathogenic mutation in the ABCC9 gene, identified by whole exome sequencing. The male proband came with multiple episodes of syncopal events and palpitations found to have advanced atrioventricular block. This case highlights the consequences of KATP channel dysfunction in the cardiovascular system.