Fetal diagnosis of left-ventricular noncompaction cardiomyopathy in identical twins with discordant congenital heart disease.

Left-ventricular noncompaction (LVNC) is characterized by prominent myocardial trabeculae with deep intratrabecular recesses. Associated with ventricular dysfunction, LVNC can present in isolation or in conjunction with structural heart defects (i.e., "nonisolated" LVNC). Although it was once considered to be difficult and unreliable, successful detection of this condition by way of fetal echocardiography has been well documented. We present what is to our knowledge the first prenatal diagnosis of LVNC in monochorionic-monozygotic twins. Nonisolated LVNC was identified in twins A and B at 23 weeks' gestation. A noncompaction-to-compaction ratio >2 was documented in both cases. Discordance for congenital heart disease was observed in the twins: Twin A presented with pulmonary atresia with an intact ventricular septum, critical tricuspid stenosis, and severe right-ventricular hypoplasia, whereas twin B presented with mild mitral valve dysplasia. Despite an initially complicated postnatal course for twin A, this case shows that it is feasible to achieve good outcomes with accurate prenatal detection and aggressive postnatal management.