The use of neutrophil lymphocyte ratio to predict complications post cardiac surgery

Cardiac surgery remains the gold standard treatment for select cohorts of patients with coronary artery and valvular heart diseases. It induces an acute systemic inflammatory response due to cardiopulmonary bypass (CPB), myocardial arrest, and surgical trauma. There is growing evidence that increased inflammation leads to greater complications and poorer outcomes for patients post cardiac surgery. Neutrophil/lymphocyte ratio (NLR) is a promising marker of inflammation. This study assessed if NLR could predict postoperative atrial fibrillation and acute kidney injury after cardiac surgery. A retrospective review of patients undergoing first-time on-pump cardiac surgery was performed. Postoperative atrial fibrillation and acute kidney injury within 7 days of surgery was recorded. Preoperative, day 1, and day 2 NLR were recorded. Potential confounders such as age, sex, comorbidities, and operative factors were included in univariate analysis. Backwards stepwise multivariate regression analysis was performed to identify independent predictors of these complications. Nine hundred and six patients were included for analysis. Higher preoperative NLR was significantly associated with postoperative atrial fibrillation. Day 1 and day 2 NLR were associated with postoperative atrial fibrillation in analyses including all patients. Older age, male gender, preexisting atrial arrhythmias, and higher EuroSCORE II also had a significant association. Diabetes mellitus was protective for postoperative arrhythmias. Preoperative NLR was not significantly associated with acute kidney injury. Day 2 NLR, older age, higher EuroSCORE II, and longer CPB time were independently associated with acute kidney injury post cardiac surgery. Higher preoperative and postoperative NLRs are associated with higher rates of complications post cardiac surgery.