Do left ventricular non-compaction findings in special populations reflect a reversible physiological adaptation or a structural cardiomyopathy with clinical implications?

Background: Left ventricular non-compaction (LVNC) describes an imaging phenotype with prominent trabeculations and a thin compacted myocardial layer. Similar appearances occur in athletes, pregnancy, and hemoglobinopathies. Their clinical interpretation requires distinction between isolated morphology and cardiomyopathy. Methods: A systematic review with narrative synthesis examined nine observational imaging reports. Imaging frequency, ventricular function, serial trabecular change and clinical events were distinguished. During revision, all nine full texts underwent design-specific JBI reassessment. Heterogeneous definitions precluded pooling. Results: Gati and Dorobantu reported fulfillment of imaging criteria in 8.1% and 6.5% of athletes; Caselli reported prominent trabeculation in 1.4%. Di Gioia reported isolated trabeculations in 435/1,492 athletes (29.1%); follow-up was available in 61.3%, limiting prognostic inference. In 102 pregnant women, 26 developed trabeculations and eight met both echocardiographic criteria. Postpartum regression was observed, although participant-flow discrepancies limit final proportions. In sickle cell disease, increased trabeculation occurred in 28/99 patients; 8.1% met both criteria. Likely overlapping thalassemia reports described frequencies of 13.3% and 7.9%, with stability reported over 5.1 years in the latter. Conclusions: Isolated LVNC-like morphology can occur without clinically evident cardiomyopathy in these populations. Pregnancy provides limited longitudinal evidence of reversibility; reversibility in athletes and hemoglobinopathies is not demonstrated by the nine analyzed reports. Preserved function and reported event-free follow-up support contextual assessment but do not establish absence of long-term risk.