<i>TRPM4</i> Mutation in Patients With Ventricular Noncompaction and Cardiac Conduction Disease

Abstract

eft ventricular noncompaction (LVNC) is characterized by abnormally prominent trabeculations and deep intertrabecular recesses in the left ventricle. 1 LVNC can range from asymptomatic to end-stage heart failure and lethal arrhythmias, which lead to sudden cardiac death. Mutations associated with sarcomere proteins, ion channels, and developmental transcription factors have been identified in patients with LVNC. At 16 years old, he was diagnosed with complete right bundle branch block and frequent premature ventricular contraction. At 25 years old, he was diagnosed with complete atrioventricular block and left ventricular dysfunction, and a permanent pacemaker was implanted. His echocardiogram exhibited prominent trabeculations and deep intertrabecular recesses in the apical to midventricular lateral wall. The noncompacted zone/compacted zone ratio was 2.3 (Figure Subsequently, symptoms of left ventricular dysfunction became progressively more severe despite medication and cardiac resynchronization therapy, and he eventually died of heart failure. The autopsy findings showed dilated ventricular lumen, whitish and filamentous prominent trabeculations in the ventricle, and thin compacted myocardium (Figure Microscopic findings showed displacement of the atrioventricular node by a fatty tissue (Figure Thickened endocardium and subendocardial fibrosis were seen, and fibrosis of trabeculae and interventricular septum were more prominent than previously reported cases. 2 Mild anastomosing broad trabeculae and staghorn-like endocardial lined spaces were seen (Figure A fibrous band was not apparent. These findings were consistent with LVNC and progressive cardiac conduction defects. His younger brother and sister (II-2 and II-3 in Figure Several years after diagnosis of LVNC, both of them developed complete atrioventricular block and received permanent pacemaker implantation. However, their parents (I-1 and I-2 in Figure