A Comparison of AlloMap versus Echocardiographic Doppler Tissue Imaging in Assessing the Presence of Rejection in Orthotopic Heart Transplant Recipients

Abstract

Purpose Cardiac allograft rejection is a significant concern amongst individuals who have undergone orthotopic heart transplantation. Currently, surveillance is performed through routine endomyocardial biopsy (EMB). While relatively safe in experienced hands, the invasive nature of the procedure lends itself to occasional complications. Several non-invasive techniques for evaluation of cardiac allograft rejection have been evaluated. In this study, we aim to compare the efficacy of two non-invasive methods of detecting rejection against the gold standard of EMB; gene expression profiling with AlloMap and echocardiographic doppler tissue imaging (DTI). Methods This was a single-center, retrospective analysis. Electronic medical records of all patients who underwent orthotopic heart transplant at our institution and had at least two concomitant measurements of AlloMap, echocardiogram DTI and endomyocardial biopsy from January 1st, 2015 to December 31st, 2017 were reviewed. Statistical analyses were performed to calculate sensitivity, specificity, negative predictive value (NPV) and positive predictive value. Rejection for EMB was defined using ISHLT guidelines and was considered present with either acute cellular rejection of 1R or greater or antibody mediated rejection pAMR1 or greater. For non-invasive studies, we considered an AlloMap score of > 34 and a DTI Results A total of 107 patients with available data were reviewed. 77% were male. Mean age was 57 years old ± 13 years with a range of 22-77 years. AlloMap and DTI performed similarly in our cohort and had NPV of 92% and 88%, respectively when compared to similarly timed EMB. Positive predictive value was 9% for AlloMap and 8% for DTI. Sensitivity was 37% for AlloMap and 18% for DTI and specificity was 65% for AlloMap and 74% for DTI. Conclusion In our cohort, AlloMap and DTI performed similarly and demonstrated excellent NPV in ruling out rejection. AlloMap has known excellent NPV and has been well-validated for this purpose. The NPV of DTI has been less studied, but performed similarly and is highly cost effective. This could have implications on future screening protocols. This study is limited by the inherent errors of a single-center, retrospective analysis. Further prospective studies to validate this data are ongoing.