Isolated non-compaction of the ventricular myocardium (INVM), also known as left 
ventricular hypertrabeculation or spongy myocardium, belongs to the 
"unclassified" cardiomyopathies according to the World Health Organization. The 
main characteristic of this entity is a prominent trabeculation of the left 
ventricle with deep intertrabecular recesses communicating with the ventricular 
cavity. The pathomechanism of INVM is thought to be an arrest in cardiac 
myogenesis with persistence of embryonic myocardial morphology. The most 
frequent clinical manifestations include congestive heart failure, ventricular 
arrhythmias and systemic thromboembolic events. The therapy of INVM comprises 
standard medical therapy for heart failure.