Association of lactate to albumin ratio and bicarbonate with short-term mortality risk in patients with acute myocardial infarction

BACKGROUND: Previous studies have indicated that the ratio of lactate/albumin (L/A) has predictive value for the prognosis of critically ill patients with heart failure. Some studies have also indicated that a low serum bicarbonate concentration is inversely related to the mortality risk of patients with cardiogenic shock. However, the value of bicarbonate and the L/A ratio for predicting the mortality risk of patients with acute myocardial infarction (AMI) is still unclear. We therefore conducted a retrospective study to research this problem. METHODS: The subjects of this study were patients with AMI, and the data source was the Medical Information Mart for Intensive Care III database. The primary endpoint was 30-day all-cause mortality after admission. The Receiver operating characteristic (ROC) curve was used to compare the predictive value of L/A ratio, lactate and albumin for end-point events. The effects of different L/A ratio levels and different bicarbonate concentrations on 7-day and 30-day all-cause mortality were compared using Kaplan–Meier (K-M) curves. Hazard ratios for different L/A ratio and different bicarbonate concentrations were investigated using COX proportional hazards models. RESULTS: The Area Under Curve (AUC) of L/A ratio, lactate, and albumin were 0.736, 0.718, and 0.620, respectively. (1) L/A ratio: The patients were divided into three groups according to their L/A ratio: tertile T1 (L/A ratio ≤ 0.47), tertile T2 (L/A ratio ≤ 0.97), and tertile T3 (L/A ratio > 0.97). The T2 and T3 groups had higher 30-day all-cause mortality risks than the T1 group. The restricted cubic spline (RCS) model indicated that there was a nonlinear relationship between L/A ratio and 30-day mortality (P < 0.05). (2) Bicarbonate concentration: The patients were also divided into three groups based on their bicarbonate concentration: G1 (22–27 mmol/L), G2 (< 22 mmol/L), and G3 (> 27 mmol/L). The G2 and G3 groups had higher 30-day all-cause mortality risks than the G1 group. The RCS model indicated that there was a nonlinear relationship between bicarbonate concentration and 30-day mortality (P < 0.05). The RCS model indicated that there was a nonlinear relationship between hemoglobin level and 30-day all-cause mortality (P < 0.05). CONCLUSION: L/A ratio and bicarbonate concentration and hemoglobin level have predictive value for predicting 30-day mortality in patients with acute myocardial infarction.