RESUMEN
Isolated non-compaction of the ventricular myocardium is a rare disorder of endomyocardial morphogenesis characterized by numerous, excessively prominent ventricular trabeculations, probably due to arrest of normal endomyocardial embryogenesis. We report two cases of isolated non-compaction of the ventricular myocardium.The first patient had a brother who died in the first year of life after heart transplantation due to refractory heart failure caused by restrictive biventricular cardiomyopathy associated with a right ventricular diverticulum. This could have been a case of isolated non-compaction of the ventricular myocardium that was not diagnosed. The patient, who is 8 years old, is asymptomatic and echocardiogram (ECG) showed multiple prominent ventricular trabeculations in the apical portion of the left ventricle, slightly depressed systolic and diastolic function and restrictive ventricular filling pattern.The second patient is a 7-year-old boy who presents recurrent syncopes. ECG showed multiple prominent ventricular trabeculations, restrictive ventricular filling pattern and normal systolic function. The Holter ECG recording showed multiple premature ventricular complexes and nonsustained ventricular tachycardia. An implantable subcutaneous Holter recorder was inserted, which was associated with an episode of aborted sudden death and polymorphic ventricular tachycardia followed by asystole. The patient was then treated with an implantable defibrillator.