Pre-operative neutrophil-lymphocyte ratio predicts low cardiac output in children after cardiac surgery

Neutrophil-lymphocyte ratio has been associated with clinical outcomes in several groups of cardiac patients, including patients with coronary artery disease, cardiac failure, and cardiac transplant recipients. We hypothesised that pre- and/or post-operative haematological cell counts are associated with clinical outcomes in children undergoing cardiac surgery for CHD. We performed a post hoc analysis of data collected as part of a prospective observational cohort study (n = 83, data available n = 47) of children evaluated for glucocorticoid receptor levels after cardiac surgery (July 2015-January 2016). The association of neutrophil-lymphocyte ratio with low cardiac output syndrome, time to inotrope free, and vasoactive-inotropic score was examined using proportional odds analysis, cox regression, and linear regression models, respectively. A majority (80%) of patients were infants (median/interquartile range 4.1/0.2-7.6 months) with conotruncal (36%) and left-sided obstructed lesions (28%). Two patients required mechanical circulatory support and three died. Higher pre-operative neutrophil-lymphocyte ratio was associated with higher cumulative odds of severe/moderate versus mild low cardiac output on post-operative day 1 (odds ratio 2.86; 95% confidence interval 1.18-6.93; p = 0.02). Pre-operative neutrophil-lymphocyte ratio was not significantly associated with time to inotrope free or vasoactive-inotrope score. Post-operative neutrophil-lymphocyte ratio was also not associated with outcomes. In children after congenital heart surgery, higher pre-operative neutrophil-lymphocyte ratio was associated with a higher chance of low cardiac output in the early post-operative period. Pre-operative neutrophil-lymphocyte ratio maybe a useful prognostic marker in children undergoing congenital heart surgery.