Plasma was obtained at the time of EMB from pediatric patients ? year old. N-terminal pro-brain natriuretic peptide was measured in fresh plasma at the time of biopsy, and cTnT was measured from frozen, stored samples using the highly sensitive assay for troponin T. Biomarker data were correlated with EMB results. Cellular AR was defined as an International Society for Heart and Lung Transplantation biopsy score of grade ?R.
Fifty-three blood samples were obtained from 42 patients (mean age 11 years). Seven episodes of AR occurred in 5 patients. Biopsies with vs without AR were associated with higher cTnT (median [interquartile range {IQR}] 66 [45-139] vs 7 [2-13] pg/mL, P = .001) and NT-proBNP (median [IQR] 11,169 [280-23,317] vs 334 [160-650] pg/mL, P < .01). After successful treatment of AR in 5 patients, cTnT fell markedly (median [IQR] 53.5 [44.8-66.5] to 10.7 [1.5-16.4], P = .05).
In this pilot study, we found marked elevation of cTnT and NT-proBNP among children with AR. Moreover, reduction in cTnT levels after treatment paralleled improvement in EMB results. If these findings are confirmed in larger prospective studies, monitoring with these biomarkers may obviate surveillance EMB.