Objective: To study the relationship between carbon dioxide combining power(CO₂-CP) and contrast-induced acute kidney injury (CI-AKI) in patients with ST segment elevation myocardial infarction and undergoing percutaneous coronary intervention.
Methods: We retrospectively analyzed 174 patients admitted to our hospital from March 2012 to August 2013 with ST segment elevation myocardial infarction and underwent emergency percutaneous coronary intervention. Patients were divided into three tertiles according to pre-operative CO₂-CP: T1 (CO₂-CP < 22.62 mmol/L), T2(CO₂-CP 22.62-24.30 mmol/L), T3(CO₂-CP > 24.30 mmol/L). Baseline clinical data, CI-AKI incidence, in-hospital mortality and dialysis rate were compared among groups. An increase in serum creatinine of >26.4 µmol/L and/or >50% from baseline within 48 hours after contrast exposure was defined as CI-AKI. Univariate logistic regression analysis was used to identify the risk factors of CI-AKI. The relationship between CO₂-CP and CI-AKI was assessed by multivariate logistic regression analysis. Receiver operating characteristic curve was used to identify the optimal cutoff of the CO₂-CP for predicting CI-AKI.
Results: CI-AKI occurred in 25 (14.4%) patients, and lower CO₂-CP was related to higher incidence of CI-AKI (27.6% (16/58) in group T1, 5.3% (3/57) in group T2, 1.7 % (1/59) in group T3, P = 0.002) and higher in-hospital mortality (10.3% (6/58) vs. 0 and 1.7% (1/59), P = 0.010). Dialysis rate was similar among 3 groups (5.2% (3/58) vs. 0 and 1.7% (1/59), P = 0.168). The incidence of CI-AKI was significantly associated with CO₂-CP < 22.00 mmol/L in univariate analyses (OR = 6.767, 95% CI 2.731-16.768, P < 0.001). After adjusting for potential confounding risk factors, CO₂-CP < 22.00 mmol/L remained significantly associated with the incidence of CI-AKI (OR = 5.835, 95%CI 1.800-18.914, P = 0.003) in multivariate logistic regression. ROC analysis revealed that the optimal cutoff of CO₂-CP to predict CI-AKI was 22.00 mmol/L (sensitivity 64.0%, specificity 79.1%, AUC = 0.714).
Conclusions: Pre-percutaneous coronary intervention CO₂-CP in patients with ST segment elevation myocardial infarction undergoing percutaneous coronary intervention is related to CI-AKI. CO₂-CP < 22.00 mmol/L predicts higher risk of CI-AKI in this patient cohort.