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.