Israel Medical Association Journal

Background: Cardiac patients express elevated levels of B-type natriuretic peptide and the amino terminal segment of its prohormone (NT-proBNP). However, there are non-cardiac causes of NT-proBNP level elevation.

Objectives: To determine the upper limit of NT-proBNP for pediatric patients with acute non-cardiac disease.

Methods: We compared NT-proBNP concentrations in healthy children and children with acute non-cardiac, mostly febrile, and acute cardiac disease. We used the Student t-test and Mann-Whitney test for group comparisons, and Pearson's and Spearman's correlation coefficients to test relationships between variables. 

Results: In 138 patients with acute non-cardiac diseases (mean age 3.7 years, 53% male), median NT-proBNP concentration was 162 pg/ml, upper limit (95% percentile) 1049 pg/ml. The level did not vary significantly by disease category; was negatively correlated with weight, weight percentile, age and hemoglobin level; and positively correlated with creatinine level. Multivariant analysis showed weight to be the only factor influencing NT-proBNP level. Levels were higher in children with acute non-cardiac diseases versus healthy children (median 88 pg/ml, P < 0.001, n= 59), and lower than levels in patients with acute cardiac disease (median 29,986 pg/ml, P < 0.001, n=29). Receiver operating characteristic analysis showed good NT-proBNP performance for differentiation between children with acute cardiac versus non-cardiac disease (area under the curve 0.958), at a cutoff of 415 pg/ml.

Conclusions: NT-proBNP levels are higher in children with acute non-cardiac diseases than in healthy children, but lower than in children with acute cardiac disease. NT-proBNP negatively correlated with weight and weight percentile.
 

Background: Surgical repair of tetralogy of Fallot may leave the patient with pulmonary regurgitation causing eventual right ventricle dilatation and dysfunction. Predicting clinical deterioration may help to determine the best timing for intervention.

Objectives: To assess whether the clinical and humoral status of patients in the second decade after repair of ToF[1] is worse than that of patients in the first decade after repair.

Methods: Twenty-one patients with repaired ToF underwent clinical assessment, electrocardiogram, echocardiogram and measurement of plasma B-type natriuretic peptide and N-terminal pro-BNP[2] as well as the 6 minute walk distance test. Patients were divided into two groups: group A – less than 10 years after repair (n=10, age < 12 years old), and group B – more than 10 years after repair (n=11, age > 12 years old). The age at repair was similar in both groups.

Results: In all but one patient the distance in the 6 min walk test was less than the minimum for age. RV[3] end-diastolic volume and the 6 min walk test correlated with age. NT-proBNP[4] levels were significantly higher in the ToF group compared to 26 healthy controls (P < 0.0001) and were inversely correlated with RV ejection fraction. Comparison of the two groups showed no difference in RV end-diastolic volume indexed for body surface area, pulmonary regurgitation severity, right or left ventricular myocardial performance index, RV ejection fraction, QRS duration, or 6 min walk indexed to minimum for age.

Conclusions: In this group of patients with similar age at operation and pulmonary regurgitation severity, most clinical, echocardiographic and humoral parameters were not worse in the second decade after repair of ToF. These data suggest that very early pulmonary valve replacement may not be of benefit.