Left Ventricular Noncompaction Cardiomyopathy: Left Ventricular Dilation and Dysfunction at Baseline Portend the Risk of Death or Heart Transplantation.

Background: Left ventricular noncompaction (LVNC) is associated with genetic and phenotypic variability that influences outcomes. We aimed to identify risk factors for death or heart transplantation (HTx) in a paediatric LVNC cohort.

Methods: We reviewed patients < 18 years of age (2001-2018) with LVNC, either isolated (I-LVNC) or with dilated phenotype (D-LVNC), and at least mildly reduced left ventricular ejection fraction (EF). Patients with dilated cardiomyopathy (DCM) were included as control subjects. Descriptive statistics, multivariate analysis, and time-to-event analysis were used.

Results: We included 188 patients, 34 (18%) with I-LVNC, 37 (20%) with D-LVNC, and 117 (62%) with DCM. Overall median age at diagnosis was 1.08 years (interquartile range [IQR] 0.22-10.65) and median follow-up was 1.4 years (IQR 0.2-5.2) years. I-LVNC patients' median baseline LVEF was 47%, compared with 33% for D-LVNC, and 21% for DCM (P < 0.0001); 62% of I-LVNC patients developed moderate to severe LV dysfunction during follow-up. The incidence of death or transplantation was 43.6% in the overall cohort. Freedom from death or HTx at 10 years after diagnosis was 88.6% (95% CI 76%-100%) for I-LVNC, 47% (95% CI 29%-65%) for D-LVNC, and 42.3% (95% CI 33%-52%) for DCM. On multivariable analysis, baseline LVEF and LV end-diastolic diameter (LVEDD) z-score were associated with death or transplantation. Patients with a baseline LVEDD z-score > 4 and moderate to severe LV dysfunction had a transplantation-free survival of 38%.

Conclusions: Baseline LV dilation and systolic dysfunction were independently associated with progression to death or HTx in LVNC patients.