Non-Compaction Cardiomyopathy: Underdiagnosed or Over Diagnosed?

Abstract

Left ventricular non-compaction (LVNC) is a morphologic description of the left ventricle that has genetic, phenotypic, and clinical heterogeneity. The clinical presentation varies from an incidental finding of LVNC in an asymptomatic patient to a patient with a cardiomyopathy with severe left ventricular systolic dysfunction. The diagnosis of LVNC in asymptomatic patients is primarily made by an echocardiogram that is performed either for screening of a first-degree relative of a patient with LVNC. There are no clinical symptoms that are specific for noncompaction. The ECG is abnormal in 87 % of patients with LVNC but there are no pathognomonic findings. Echocardiography is the most frequently used method to diagnose LVNC. The echocardiographic diagnostic criteria for LVNC are well established and it includes the demonstration of a thickened myocardium exhibiting a noncompacted endocardial layer and a compacted epicardial layer. The ratio of the systolic thickness of noncompacted to compacted layer is >2. CMR is well suited to evaluate the layers of myocardium and distinguish the regional characteristic of this disease by the 3-dimensional nature of the technology. This promising imaging modality provides both a high spatial resolution and a good contrast between trabeculations and blood pool. CT similar to CMR possesses inherent high resolution imaging characteristics. It too is well suited to measure the disparity of noncompacted to compacted myocardium. To minimize underdiagnosing or over diagnosing LVNC it is essential to have a sound understanding of the genetics, clinical characteristics and strengths and weaknesses of the imaging modalities used for the evaluation and management of patients with known or suspected LVNC. In this review paper we detail the genetic and clinical background of LVNC, and the added value of echocardiography, CMR and CT for the diagnosis or exclusion of LVNC.