Use of Postoperative Peak Arterial Lactate Level to Predict Outcome After Cardiac Surgery.

OBJECTIVES In the present study, the authors investigated the predictive value of postoperative peak arterial lactate levels for early and late mortality after cardiac surgery. DESIGN Retrospective analysis of prospectively collected data. SETTING Single-center study in an academic hospital. PARTICIPANTS Adult patients who underwent cardiac surgery between 2004 and 2014 (n = 16,376). INTERVENTIONS Different cardiac surgical procedures. MEASUREMENTS AND RESULTS Patients were classified according to the peak arterial lactate level (PALL) within 3 days postoperatively. Logistic regression analysis and Cox regression analysis were performed to identify postoperative peak arterial lactate level as a predictor for early and late mortality respectively. In 8460 patients (51.7%), lactate was not measured postoperatively because these patients were managed according to the fast-track protocol. These patients constituted group 1 in our population but were excluded from the regression analysis. The remaining patients (n = 7,916; 48.3%) were divided according to the postoperative peak arterial lactate level (PALL): PALL<5 mmol/L (group 2), PALL 5 to 10 mmol/L (group 3), and PALL of>10 mmol/L (group 4). Early mortality was 3.7%, 20.4%, and 62.9% in groups 2, 3, and 4 respectively (p<0.0001). This mortality rate was significantly higher than that of group 1 (1.6%); p<0.0001. Multivariate regression analyses revealed postoperative peak arterial lactate as a significant predictor of 30-day mortality (odds ratio = 1.44 [1.39-1.48], p<0.001) as well as for late mortality (hazard ratio = 1.05 [1.01-1.10], p<0.025). CONCLUSIONS Postoperative peak arterial lactate level in patients undergoing cardiac surgery is an independent predictor for both early and late mortality.