Original article Usefulness of NT-proBNP in assessment of right ventricular function in children after tetralogy of Fallot correction – a preliminary study

Abstract

Background: Although surgical treatment for tetralogy of Fallot (TOF) has been used with considerable success, right ventricular function may remain altered after repair. The NT-proBNP assessment has been shown to be a reliable parameter for the heart failure assessment.
Aim: To determine NT-proBNP values in assessment of right ventricular function in children after TOF correction.
Methods: In 20 patients after TOF correction aged from 10 to 17 years (follow-up period ranged from 7 to 16 years) NT-proBNP level at rest and after exertion, treadmill test and echocardiography were performed. In the control healthy children NT-proBNP level at rest was assessed.
Results: The mean values of NT-proBNP level in the TOF patients were significantly higher than in controls (11.0 ± 12.0 fmol/l and 5.4 ± 7.5 fmol/l, p < 0.05). In patients repaired with a transannular patch the mean value of NT-proBNP level was higher than in children operated on without a transannular patch (18.3 ± 16.5 vs. 6.8 ± 7.9 fmol/l, p < 0.05). In children in whom physiological shortening of QRS complex during treadmill test was observed, NT-proBNP level was lower (mean values at rest 5.0 ± 4.8 fmol/l and after exertion 7.3 ± 6.3 fmol/l) compared to patients with prolongation of QRS duration (mean values at rest 17.7 ± 15.6 fmol/l and after exertion 20.3 ± 17.8 fmol/l) (p < 0.05). Significant differences in NT-proBNP levels between children with severe pulmonary regurgitation and mild/moderate pulmonary regurgitation were detected (mean values at rest 18.6 ± 15.0 vs. 4.2 ± 3.9 fmol/l and after exertion 20.0 ± 18.6 vs. 5.7 ± 4.6 fmol/l) (p < 0.05). The NT-proBNP levels were also higher in children with severe tricuspid valve insufficiency compared to children with mild/moderate tricuspid valve regurgitation (mean values at rest 19.5 ± 15.0 vs. 4.9 ± 3.7 fmol/l and after exertion 22.5 ± 17.1 vs. 7.0 ± 4.6 fmol/l).
Conclusions: The NT-proBNP level in patients after TOF correction is higher than in healthy children. The NT-proBNP level is higher and exertion tolerance is lower in children repaired with rather than without transannular patch. In patients with severe pulmonary regurgitation and/or severe tricuspid valve insufficiency NT-proBNP level is higher than in patients without right ventricular volume overload. The measurement of NT-proBNP level might be helpful in order to separate those patients after TOF correction who are at increased risk of heart failure and arrhythmia.