Normalization of N-Terminal Pro-B-Type Natriuretic Peptide After Cardiac Surgery Among Children With Tetralogy of Fallot

Abstract

The aim of this study was to temporally measure N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels over a period of 18 months after corrective surgery among children with tetralogy of Fallot (TOF) and to explore how commonly used pharmaceuticals (i.e., spironolactone and digoxin) might affect the normalization pattern. This retrospective study included 136 children with a median age of 7 months who underwent cardiac surgery for TOF. NT-proBNP level was measured at 1, 3, 6, 12, and 18 months after the surgery. Normalization of NT-proBNP was defined as an NT-proBNP level ≤250 pg/ml. The commonly used pharmaceuticals spironolactone and digoxin after discharge were collected. The normalization pattern, normalization time, and potential influence of the pharmaceuticals were determined. The rate of normalization was 24.2% (95% confidence interval [CI] 8.58% to 68.4%) per 100 person-days. Kaplan-Meier survival analysis showed a median normalization time of 517 (95% CI 429.6 to 604.3) days. The children whose NT-proBNP level did not normalize had a significantly higher readmission rate than those whose NT-proBNP level normalized (19.0% vs 2.8%, p = 0.018). Multivariable logistic regression models confirmed that the regular users of spironolactone, alone (odds ratio = 1.45, 95% CI 1.15 to 1.83) or in combination with digoxin (odds ratio = 1.28, 95% CI 1.03 to 1.58), had markedly faster recovery trajectories for measures of NT-proBNP than the irregular users of both. In conclusion, NT-proBNP normalization after cardiac surgery for TOF is a lengthy process, and irregular use of spironolactone could lead to failure in recovery and hospital readmission.