Neutrophil-Lymphocyte Ratio: Prognostic Significance in Patients Undergoing Cardiac Surgery- Early Results and Long-Term Survival

Introduction:
Neutrophil-to-lymphocyte ratio (NLR) is an inflammatory marker associated with poor outcomes in a variety of clinical settings. We sought to determine the prognostic significance of preoperative elevated NLR in patients undergoing cardiac surgery.

Methods:
We retrospectively examined 1000 consecutive patients who underwent cardiac surgery, 989 had preoperative neutrophil and lymphocyte count. ROC was used to determine the cutoff value for elevated NLR. Univariate analysis was used to compare patients with elevated NLR to those with low NLR. Multivariate regression was used to determine the predictive value of preoperative NLR on clinical outcomes.

Results:
By Univariate analysis, patients with elevated NLR were older (p<0.0001), had a higher incidence of LV dysfunction (p=0.0003), had a higher incidence of mitral regurgitation (p=0.0008), higher pulmonary pressure (p<0.0001), and higher EuroSCORE (p<0.0001). By multivariate analysis, elevated NLR emerged as an independent predictor of operative mortality (HR 2.46, CI 1.4-4.4, p=0.002); pleural effusion (HR 1.8, CI 1.33-2.44, p=0.0001); low output syndrome (HR 2.41, CI 1.65-3.54, p=<0.0001); prolonged ventilation (HR 1.8, CI 1.34-2.45, p=0.0001) or any of the above complications (HR 1.84, CI 1.38-2.46, p<0.0001). Follow-up for survival up to 5 years was available in 845 (93%). NLR emerged as a predictor of late mortality (p<0.0001).

Conclusions:
Preoperative elevated NLR is associated with a higher incidence of adverse events after cardiac surgery, as well as decreased late survival. Further studies are warranted in order to determine whether prophylactic treatment with anti-inflammatory agents can prevent such outcomes. It may be warranted to include the baseline NLR as a parameter in risk stratification of patients about to undergo cardiac surgery.