NLR and PLR as an indicator of outcomes following uneventful cardiac surgery

Background: Patients with coronary artery disease and valvular heart diease continue to be referred for cardiac surgery after medical management fails or in cases where it isn’t feasible. These patients are susceptible to infection and inflammation due to previous MI, cardiopulmonary bypass and the stress associated with surgery itself. Most of these patients also have associated co-morbidities that further increases the risk of post-operative complication. Neutrophil/lymphocyte ratio (NLR) and Platelet/lymphocyte ratio (PLR) is a gaining popularity as a marker of inflammation. Hence we conducted this study to see if NLR and PLR can be used as indicators of outcomes following uneventful cardiac surgery. Methods: A retrospective study was performed on patients undergoing off-pump CABG, on-pump CABG and valve surgeries. Demographic details was noted of all the patients. Postoperative outcomes such as ST-T changes, other arrhythmias, acute kidney/liver injury, wound infection or LRTI within 7 days of surgery was noted and documented. Surgery related factors- cross clamp time, bleeding, challenges in weaning off bypass and operative time were also recorded. Preoperative, day 1, and day 2 NLR and PLR was recorded. Results: Two hundred and six patients in the study. Elevated Pre-op and post-op NLR and reduced PLR values was significantly associated with post-operative ST-T changes and LRTI, with a weak positive correlation between NLR and wound discharge. Additionally, we found that NLR and PLR showed a weak negative correlation with type II diabetes mellitus, pump time/ surgery time > 120 minutes and patients with history of recent MI. Higher preoperative NLR and reduced PLR was significantly associated with postoperative acute liver injury. Conclusions: Higher preoperative and postoperative NLR and reduced PLR is associated with higher rates of complications post-cardiac surgery.