Background: INVM is characterized by a left ventricle with prominent trabecular meshwork, which has been thought to be due to an arrest of myocardial morphogenesis during fetal life. However, increasing number of juvenile or adult cases, with longer clinical course have been also reported recently.
Methods: We analyzed the clinical features and anatomical properties of infantile INVM (< 2 years: 43 cases) in comparison with juvenile (2-15 years: 45 cases). We developed a new echocardiographic criteria “noncompaction score” to estimate the severity of noncompacted myocardium add to N/C ratio.
Results: Although most of patients in infantile type had clinically signs or symptoms of heart failure such as dyspnea at initial presentation (63%), a greater number of asymptomatic patients were identified because of such as abnormalities on screening ECG in juvenile type (60%). The incidence of WPW syndrome was higher (16.4%), in contrast, the incidence of LBBB and VT was rarer than those reported among adults. In echocardiographic findings, the maximum N/C ratio was observed in the apex in both types. Noncompaction score and N/C score were not significant difference in both groups. Therefore LVEF at initial presentation in infantile type was lower than juvenile type significantly (45.8 ±4.0 vs. 61.6 ±2.0 : p < 0.001). Although the survival analysis showed poor prognosis in infantile type, the significant risk factor was below 50% LVEF (p=0.008, HR=18.8), and heart failure at diagnosis (p=0.008, HR=13.4).
Conclusions: INVM in both type showed poor prognosis correlated with depressed LVEF and heart failure
at diagnosis.