Preoperative albumin corrected anion gap is associated with in-hospital and long-term mortality in patients undergoing coronary artery bypass grafting in a retrospective cohort study

BACKGROUND: Coronary artery disease remains a global health concern and the leading cause of death. Till today, coronary artery bypass grafting (CABG) is one of the main treatment strategies for coronary artery disease, especially for Multivessel coronary disease or complex coronary lesions. The present study aimed to explore the relationship of preoperative albumin corrected anion gap (ACAG) with mortality in all those patients who undergoing CABG. METHODS: All the patients undergoing CABG were included in the study. All clinical data were collected from CareVue and MetaVision system. The predictive value of ACAG for mortality was determined by receiver operating characteristic (ROC) curves survival curves were estimated using the Kaplan-Meier method. Multivariate regression models were constructed to determine the association of ACAG with mortality. RESULTS: A total of 2,180 patients were identified and divided into a high ACAG group (ACAG ≥16.0 mmol/L) and low ACAG group (ACAG <16.0 mmol/L) according to the ROC analysis. Patients in the high ACAG group were older and presented with more comorbidities and concomitant valvular surgeries. Further more, in the high ACAG group, we observed a higher length of stay in the intensive care unit [3.88 (2.15, 7.09) vs. 2.29 (1.29, 3.94), P<0.001]. Both the in-hospital mortality [28 (4.5%) vs. 11 (0.7%), P<0.001], and the 4-year mortality [125 (27.1%) vs. 111 (12.7%), P<0.001] were also rised in those patients. And it was also showed in the survival curves, patients with ACAG ≥16.0 mmol/L had a significant lower 4-year survival (P<0.001). While in the multivariate regression model, we found ACAG was act as an independent risk factor for both the in-hospital mortality [odds ratio (OR): 1.248 (1.060, 1.470), P=0.008] and the 4-year mortality [hazard ratio (HR): 1.134 (1.063, 1.210), P<0.001]. An ACAG ≥16.0 mmol/L was significantly associated with a 2.7-fold risk of in-hospital mortality [OR: 2.732 (1.129, 6.610), P=0.026]. CONCLUSIONS: Preoperative ACAG is an independent risk factor for in-hospital and long-term mortality in CABG patients. A higher ACAG may relate to severe coronary artery stenosis and cardiac dysfunction, which is more likely to lead to a postoperative systemic inflammatory response, microcirculation disorder, and subsequent complications.