NTproBNP as a marker of rejection in pediatric heart transplant recipients

Acute rejection is a major morbidity in heart transplant recipients; diagnosis is difficult, and rejection must often be treated reactively. Various serum biomarkers have been investigated for non-invasive monitoring of the cardiac allograft. NTproBNP is produced by the ventricular myocardium and may increase with evolving rejection allowing earlier diagnosis. Retrospective review of serum NTproBNP levels in pediatric heart transplant recipients has been carried out to evaluate the association with episodes of acute rejection. Repeated measures logistic regression was used to model associations for variables with first rejection and within an individual for change in NTproBNP and first rejection. Odds ratios for rejection risk given an increase in serum NTproBNP were calculated. Correlation of NTproBNP levels with renal function as estimated by modified Schwartz equation was performed to look for confounding. Higher serum NTproBNP level was associated with increased risk of rejection, but intersubject variability was wide. However, increase in an individual subject's serum level showed increased risk of rejection, greater with greater rise. Serum NTproBNP levels appear not greatly affected by renal function. NTproBNP shows promise in surveillance for pediatric heart transplant recipients. The greatest use appears to be in following trends for an individual instead of using an absolute value.