Left Ventricular Noncompaction Syndrome

Left ventricular noncompaction (LVNC) has been classified as a primary cardiomyopathy, predominantly involving the left ventricle, although right ventricular and biventricular involvement have also been reported. The condition may coexist with neuromuscular disorders, congenital cardiac anomalies, and chromosomal abnormalities. Despite its established recognition, LVNC continues to pose a significant challenge, with divergent classifications among major societies: the American Heart Association categorizes LVNC as a primary genetic cardiomyopathy, whereas the European Society of Cardiology and the World Health Organization consider it an unclassified cardiomyopathy. This discordance reflects the condition's marked heterogeneity; while historically attributed to embryogenic arrest, contemporary evidence supports a complex genetic landscape with substantial phenotypic overlap with hypertrophic and dilated cardiomyopathies. Consequently, the traditional classification remains controversial, as diagnostic criteria based on the ratio of trabeculated to compacted myocardium have been identified in up to 20% of individuals without cardiomyopathy and have also been observed in physiological states such as pregnancy and in athletes, likely reflecting adaptive responses to increased preload. Although LVNC is frequently asymptomatic, a subset of patients is at increased risk of thromboembolic events, left ventricular systolic dysfunction, malignant arrhythmias, and sudden cardiac death.