Left Atrial Function Correlates With Fibrosis in Pediatric Heart Transplant Recipients

PURPOSE: Pediatric heart transplant patient (PHT) surveillance for chronic graft failure (CGF) remains challenging. Novel echo parameters such as left atrial strain (LAS) has shown to correlate with diastolic dysfunction (DD). However, its role in CGF surveillance in the absence of significant DD has not been well studied in PHT especially in the presence of left atrial anastomosis. METHODS: Left atrial reservoir, conduit and contractile strain (LAS-r, LAS-cd, LAS-ct), segmental LAS-r (septal wall, lateral wall, and roof), mitral valve (MV) E/A, average E/e', and indexed LA volume were measured on PHT echocardiograms performed within 3 months of surveillance cardiac catheterization at a single center (01/01/21-12/31/21); those with acute rejection on EMB were excluded. EMB was reviewed for qualitative fibrosis (graded on a scale of 0-5) as a histopathological surrogate of CGF. Correlation was studied between echo variables versus fibrosis and pulmonary capillary wedge pressure (PCWP) on cath. RESULTS: Eighty-four PHT (mean age 11 years, SD: 6.2 years) with median time since transplant of 4.0 years [IQR: 2.0-8.0]) were studied. Mean LV EF was 65% (SD = 5.7%). Mean LAS-r was 23.4% (SD = 8.7%) which was significantly decreased compared to age-matched normative data. Decreased septal and lateral wall LAS-r correlate with elevated PCWP. Median fibrosis score was 3.0 (IQR 2-3.8) and correlated with MV E/A (r = 0.32, p = 0.009) and LAS-ct (r = -0.22, p = 0.043). CONCLUSIONS: LAS in PHT is decreased compared to age normative values, even in the setting of normal LV systolic function. Left atrial function assessed by global and segmental strain show correlations with EMB fibrosis and PCWP on cardiac catheterization in the absence of rejection. Longitudinal follow up is needed to further study the relationship of these diastolic function measures to CGF outcomes.