left ventricle non - compaction ( lvnc ) or persistence of spongy myocardium is a rare form of congenital cardiomyopathy which presents with cardiac failure , thromboembolic events , arrhythmia and sudden death . we report a family with two deceased children and two alive offspring diagnosed with left ventricular ( lv ) non - compaction . a 9-year - old boy and a 16-year - old girl of our reported family suddenly died following exercise and emotional provocation . both had a history of convulsion and syncope , with the latter taking anticonvulsant medication . the remaining two offsprings , one boy and one girl were diagnosed as having isolated lvnc . syncope and convulsion can be first manifestations of lvnc and heralding signs for sudden death in patients with lvnc . isolated left ventricular non - compaction ( lvnc ) is one of the rare genetic heart diseases recently known , and characterized by heterogeneous defects in endocardium accompanied by increased trabeculation due to abnormal embryogenesis of the normal myocardium . in this disease , the myocardium is composed of two layers : spongy or non - compacted and normal or compacted ones . the clinical manifestations include symptoms and signs of left ventricular failure ( common ) , those of right ventricle ( rare ) , ventricular arrhythmias , sudden death , mural thrombi and embolic events with cardiac origin . we report a family having the history of two offspring deaths , at the ages of 9 and 16 , with two live ones suffering from lvnc . we reported sudden death of a 9-year old boy with a history of two episodes of unprovoked convulsion and syncope in school and his 16-year old sister due to sudden death while she was getting back home after a feast . a 12year - old boy and a 7-year - old girl were referred to pediatric cardiology clinic for cardiac evaluation following occurrence of sudden death in their siblings . the first pregnancy of the mother ended in abortion at the age of two months of gestation , and the second offspring was a girl who died one week after birth following an operation to repair esophageal atresia . the first victim of suspected lvnc in this family was a nine year old boy with a history of two episodes of unprovoked convulsion and syncope in school . the first attack was in break time with spasm of neck and body , ended uneventfully . the next one was during exercise , with sudden fall but no urinary incontinence , eye deviation or sialorrhea . the electrocardiogram ( ecg ) , electroencephalography and lab tests showed no abnormalities at that time . the family lost their 16-year old daughter due to sudden death while she was getting back home after a feast . she also had experienced two seizure episodes associated with loss of consciousness , one at the age of 9 during exercise at school and the other at the age of 10 on vacation . both episodes had ended uneventfully , and brain ct scan with contrast demonstrated no pathologic finding . the 12-year - old boy had no history of seizure , syncope , easy fatigability , exertional dyspnea or hospitalization . on 2d transthorasic echocardiography , the parasternal short axis and four chamber views demonstrated increased left ventricular ( lv ) wall thickness accompanied by trabeculations and deep recesses that were indicative of lv non - compaction . four chamber and short axis views demonstrating the ratio of non - compacted to normally compacted segments the coronary arteries were normal and no pericardial effusion and intracavitary thrombi were detected . the 7-year - old girl also had no positive history of hospitalization , seizure , easy fatigue . her ecg was normal , however , her 2d echocardiograms were compatible with the diagnosis of lv non - compcation , based on the diagnostic criteria already reported by frischknecht et al , with increased lateral , inferior and apical wall thickness and deep recesses and trabeculations . the coronary arteries were normal and no pericardial effusion and intracavitary thrombi were detected ( fig . parasternal long axis view and m - mode echocardiography showing abnormal trabeculation and spongy pattern of left ventricle the parents were evaluated clinically and by echocardiography . this case report highlights the importance of syncope and seizure as heralding signs for sudden death in two deceased children of a family with two offspring having documented lv non - compaction . although syncope and sudden death have been previously reported in adults with lvnc but to date , as to best of our knowledge , sudden death with prior heralding sign of syncope and seizure has not been reported in children with lv non - compaction . in our reported family , both of the unexpected deaths occurred after previous episodes of uneventful seizure and syncope . considering the common embryologic origins of central nervous system and myocardium , occurrence of syncope and seizure in lvnc could be explained . lv non - compaction or persistence of spongy myocardium , first described in 1984 , is a rare form congenital cardiomyopathy with a prevalence of 0.05 - 0.24/year . the limitation of our report is lack of echocardiographic evidence for confirmation of diagnosis in the two deceased and not timely - referred and timely - diagnosed children . we suggest careful biannual follow up ( ecg , holter monitoring , echocardiography ) and anticoagulation therapy ( aspirin , dose : 3 - 5mg/ kg / daily ) for alive sibling . unexplained seizure and syncope in a child , particularly in a familial pattern , may warrant further echocardiographic evaluation for early diagnosis of left ventricular non - compaction to prevent catastrophic events . although the numbers of our patients are limited , but it seems that seizure and syncope can be considered as warning signs in those patients with lvnc who are at high risk for sudden death .