Decreasing Endomyocardial Biopsy Frequency in Pediatric Heart Transplantation Using a Rejection Risk Prediction-A Single Center Study

PurposeAcute rejection remains an important cause of morbidity and mortality after pediatric heart transplantation (HT). Endomyocardial biopsy (EMB) is the gold standard for rejection diagnosis but comes with procedural risk. EMB frequency varies significantly across centers. Since 4/2018, our center's surveillance EMB schedule is based on a rejection risk prediction score (Fig 1). We aimed to evaluate outcomes in the 1st year post-HT before and after risk score implementation.MethodsPatients <18 years of age who underwent HT at our center from 1/2015 to 12/2020 were reviewed. Primary endpoint was rejection-free survival at 1 year post-HT. Clinical characteristics were compared for patients transplanted in era 1 (before 4/2018) and era 2 (after 4/2018). Cumulative 1 year, rejection free survival with and or without hemodynamic compromise (HC) was compared between eras using Kaplan Meier survival analysis.ResultsIn total, 115 patients underwent HT during the study period (53 in era 1, 62 in era 2). Significant differences were not seen in clinical characteristics (Fig 2A) or in rejection free survival with or without HC between eras. No significant difference in freedom from rejection with and without HC was identified between eras (Fig 2B, C). There was a 60% reduction in the median number of EMB in the 1st year post-HT after employing the score (5 in era 1, 2 in era 2, p <0.001) (Fig 2D).ConclusionSafe reduction in EMB frequency can be achieved when employing a rejection risk prediction score as depicted by our center's experience decreasing EMB frequency without increasing frequency of early rejection. Acute rejection remains an important cause of morbidity and mortality after pediatric heart transplantation (HT). Endomyocardial biopsy (EMB) is the gold standard for rejection diagnosis but comes with procedural risk. EMB frequency varies significantly across centers. Since 4/2018, our center's surveillance EMB schedule is based on a rejection risk prediction score (Fig 1). We aimed to evaluate outcomes in the 1st year post-HT before and after risk score implementation. Patients <18 years of age who underwent HT at our center from 1/2015 to 12/2020 were reviewed. Primary endpoint was rejection-free survival at 1 year post-HT. Clinical characteristics were compared for patients transplanted in era 1 (before 4/2018) and era 2 (after 4/2018). Cumulative 1 year, rejection free survival with and or without hemodynamic compromise (HC) was compared between eras using Kaplan Meier survival analysis. In total, 115 patients underwent HT during the study period (53 in era 1, 62 in era 2). Significant differences were not seen in clinical characteristics (Fig 2A) or in rejection free survival with or without HC between eras. No significant difference in freedom from rejection with and without HC was identified between eras (Fig 2B, C). There was a 60% reduction in the median number of EMB in the 1st year post-HT after employing the score (5 in era 1, 2 in era 2, p <0.001) (Fig 2D). Safe reduction in EMB frequency can be achieved when employing a rejection risk prediction score as depicted by our center's experience decreasing EMB frequency without increasing frequency of early rejection.