Congenital Complete Atrioventricular Block Associated with QT Prolongation: Description of a Patient with an Unusual Outcome

The association of a complete atrioventricular block with long QT syndrome is relatively common and carries a high risk of torsades de pointes (TdP) and sudden death. It is probably due to a downregulation of potassium channel currents (IKs and IKr) that impairs ventricular repolarization, prolongs the QT interval and increases susceptibility to TdP, so it must be considered a channelopathy. This report describes a 6 year-old boy, with a complete atrioventricular block diagnosed at 5 months of age, who at the age of 1 year started having episodes of TdP associated with a prolonged QT interval. He was treated successfully with propranolol and with a pacemaker implant. At age 3 the complete atrioventricular block reversed spontaneously to a first degree atrioventricular block.