Reversible Dilated Cardiomyopathy Caused by a High Burden of Ventricular Arrhythmias in Andersen-Tawil Syndrome.

Andersen-Tawil syndrome (ATS) is caused by mutations in KCNJ2 (Kir2.1). It remains unclear whether dilated cardiomyopathy (DCM) is a primary feature of ATS. We studied a proband with typical physical features of ATS plus DCM and moderate to severe left ventricular dysfunction (left ventricular ejection fraction = 30.5%). Genetic screening revealed a novel mutation in Kir2.1 (c.665T>C, p.L222S). Functional studies showed that this mutation reduced ionic currents in a dominant-negative manner. Suppression of ventricular arrhythmias with bisoprolol led to normalization of left ventricular size and function. We conclude that DCM is likely a secondary phenotype in ATS and is caused by high ventricular arrhythmia burden.