P0388 - Echocardiographic Predictors of Acute Cellular Rejection in Pediatric Heart Transplant Recipients

Background/Purpose
Surveillance for acute cellular rejection (ACR) among pediatric heart transplant recipients largely relies on invasive endomyocardial biopsy. Echocardiography has the potential for such evaluation but has yet been proven to be as reliable as invasive measures. This study investigates the accuracy of common echocardiographic right and left heart indices for the detection of biopsy proven ACR and their ability to serve as prognostic indicators for long-term graft integrity.

Methods
This retrospective observational study involved review of medical records of all patients with biopsy proven acute cellular rejection. Determination of ACR was based on final pathology report using definitions established by the International Society for Heart and Lung Transplantation grading system. Echocardiographic data was extracted from three time points: (1) baseline: preceding the episode of ACR; (2) during ACR episode; (3) first follow-up data point after treatment of ACR. Echocardiographic measures evaluated included E/e’, fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE), left ventricular posterior wall thickness in diastole (LVPWTd), left ventricular posterior wall thickness in systole (LVPWTs), the ratio of systolic to diastolic duration (S/D ratio), and Tricuspid Valve s’. Percent change from baseline was calculated for each parameter and tested for a difference from zero (no change) using a Wilcoxon sign rank test.

Results
48 patients [56% male] had a total of 84 ACR episodes. During ACR FAC (Mean -17.1% reduction, p<0.001) and TAPSE (Mean – 8.9% reduction, p<0.001) deteriorated and LVPWT in both systole (Mean 8.3% increase, p=0.016) and diastole (Mean 9.0% increase, p=0.012) increased. 31 of 48 patients developed graft failure defined as death or need for re transplant. There was no difference in echocardiographic measures between those whose ACR continued to graft failure as compared to those who recovered from ACR.

Conclusion
Decreases in both FAC and TAPSE and increases in LVPWT in systole and diastole occur in ACR and may be indicated as screening tools to serve as valuable adjuncts to reduce the number of endomyocardial biopsies performed for rejection surveillance. Furthermore, this study demonstrates that such parameters do not have prognostic value for long term graft integrity but are reversible and that any ongoing damage is not detectable by these indices.