Anne-Marie Koop

286 RESULTS Clinical and echocardiographic characteristics One-hundred and twenty-five children with (a history of) RV overload were included in this study. Anatomical diagnoses included tetralogy of Fallot (TOF) (61%), PH (20%), and atrial septal defect (ASD) (5%). Diagnosis with TOF embodied TOF, corrected TOF, pulmonary atresia and pulmonary stenosis. Children with PH had either PH associated with CHD (n=14) or PH not associated with CHD (n=11) and were classified according to the most recent Nice classification. 26–28 Fourteen percent of the children had other diagnoses (e.g. RV-pulmonary artery (PA) conduit stenosis) ( table 1 ). Fifty-six children (44%) were assigned to the group of RV pressure overload, 25 children (20%) to the group of RV volume overload and 28 children (23%) to the group of combined overload of the RV (predominantly volume overload, n=11; predominantly pressure overload, n=2; type of loading equally distributed n=15). Sixteen children (13%)with correctedCHDhadno residual RVoverload and formed the reference. Patient characteristics, including functional status and echocardiographic parameters, stratified for the type of RV overload are summarized in table 1 . Biomarker plasma levels in relation to the type of RV overload Plasma levels of NT-proBNP and ET-1 were significantly higher in the children with RV pressure overload compared to the reference group. Plasma ET-1 levels were also significantly higher when compared to the combined RV overload group ( table 2 ). Biomarker plasma levels in relation to the severity of RV overload By expressing plasma levels of each biomarker as a ratio to the respective values in the reference group, we obtained multi-biomarkers profiles for patients according to type and degree of RV overload ( figure 1 ). Biomarker plasma levels were most pronouncedly increased in children with RV pressure overload, and less in those with RV volume overload or those with combined RV overload. Plasma levels of NT-proBNP and ET-1 increased with the severity of RV pressure overload, while hsTnT and GDF-15 were significantly increased only in children with severe RV pressure overload. GDF-15 serum levels showed a trend of increase in children with mild-moderate RV pressure overload ( figure 1a ). Children exposed to RV volume overload showed a different multi- biomarker profile, characterized by smaller differences in biomarker plasma levels in relation to the degree of overload, that failed to reach statistical significance ( figure 1b ). The plasma level of neprilysin in children with abnormal RV loading in contrast to other investigated biomarkers, tended to decrease, independent of the type of overload. Plasma levels of NT-proBNP and ET-1 increased with the severity of RV pressure overload.