Key Questions relating to left ventricular noncompaction cardiomyopathy - Is the Emperor still wearing any clothes?

Abstract The evidence is increasing that left ventricular noncompaction cardiomyopathy, as it is currently defined, does not represent failure of compaction of pre-existing trabecular myocardium found during embryonic development so as to form the compact component of the ventricular walls. Nor is there evidence, of which we are aware, to favour the notion that the entity is a return to a phenotype as seen in cold-blooded animals. It is also known that, when seen in adults, the presence of excessive ventricular trabeculations does not portend a poor prognosis when ejection fraction is normal, with the risks of complications such as arrhythmia and stroke being rare in this setting. It is also the case that images of “noncompaction” as provided from children, or in autopsy studies, are quite different from the features observed clinically in the asymptomatic adults with excessive trabeculation. Our review suggests that the presence of an excessively trabeculated left ventricular wall is not, in itself, a clinical entity. It is equally possible that the excessive trabeculation is no more than a bystander in the presence of additional lesions, such as dilated cardiomyopathy, with the additional lesions being responsible for the reduced ejection fraction bringing a given patient to clinical attention. We, therefore, argue that the term “noncompaction cardiomyopathy” is misleading, as there is neither failure of compaction nor a cardiomyopathic process in most individuals that fulfil widely used diagnostic criteria.