Oswaldo A. Ángel-Bran, Departamento de Cardiología, Instituto Nacional de Cardiología Ignacio Chávez, Ciudad de México, México
Rodrigo Gopar-Nieto, Unidad de Cuidados Coronarios. Instituto Nacional de Cardiología Ignacio Chávez, Ciudad de México, México
Daniel Manzur-Sandoval, Unidad de Terapia Intensiva Cardiovascular, Instituto Nacional de Cardiología Ignacio Chávez, Ciudad de México, México

Introduction: Cardiovascular diseases are the leading cause of death globally, with a significant burden in low- and middle-income countries. Cardiac surgery, particularly in specialized cardiovascular ICUs, presents challenges in risk stratification. Traditional severity scores often fail to account for postoperative factors, such as inflammation, which can influence outcomes. The neutrophil-to-lymphocyte ratio (NLR) is a low-cost, easily obtainable marker of systemic inflammation that has shown potential as a prognostic tool in various ICU settings, but its utility in post-cardiac surgery patients remains insufficiently studied. Objective: To evaluate the prognostic value of the NLR ratio in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) admitted to a cardiovascular intensive care unit. Methods: This observational, retrospective study included 545 patients who underwent cardiac surgery with cardiopulmonary bypass (CPB) at the Instituto Nacional de Cardiología. NLR was calculated using neutrophil and lymphocyte counts at ICU admission, with a cutoff of NLR > 4 defining the “high NLR” group. We assessed demographic, clinical, and surgical characteristics, and examined associations between abnormal NLR and postoperative complications, including length of hospital stay, acute kidney injury (AKI), and mortality. Results: Among the cohort, 136 patients had an elevated NLR. Those with high NLR exhibited a significantly longer hospital stay (median 13 days vs. 10 days; p = 0.03). Although no differences in mortality or major complications were observed, trends indicated that elevated NLR was associated with higher rates of AKI and blood transfusions. Conclusions: Elevated postoperative NLR in cardiac surgery patients is associated with longer hospital stays and may serve as a cost-effective tool for risk stratification. Further prospective studies are needed to clarify its predictive role and underlying mechanisms in this population.

Keywords: Neutrophil-to-lymphocyte ratio. Cardiac surgery. Prognostic biomarkers.