Perioperative Hyperlactemia Is a Poor Predictor of Outcome in Patients Undergoing Surgery for Acute Type-A Aortic Dissection

Objective: In patients presenting with acute type-A aortic dissection (aTAAD), lactic acid measurement is a frequently used analysis for diagnosis of acute ischemia, which may have a dismal prognosis. The aim of the current study was to determine the performance of perioperative arterial lactic acid measurements in predicting outcome in aTAAD patients. Design: Retrospective, observational study. Setting: Cardiothoracic surgery unit at a tertiary-level hospital. Participants: The study involved 285 consecutive patients undergoing surgery for aTAAD. Interventions: Preoperative and postoperative lactic acid levels were measured and evaluated together with clinical data related to outcome, including in-hospital and 1-year mortality. Measurements and Main Results: Altogether, 37 patients (13%) died during the index hospital admission, and survival was 84.4 ± 2.2 at 1 year. Preoperative cardiac malperfusion (odds ratio [OR] 3.1; 95% confidence interval [CI] 1.3-7.3) and cerebral malperfusion (OR 2.6; 95% CI 1.2-5.6) were associated significantly with poorer 1-year survival. The area under the curve (AUC) for in-hospital and 1-year mortality in relation to preoperative lactic acid levels was 0.684 and 0.673, respectively, corresponding to a lactic acid cut-off for in-hospital mortality of 2.75 mmol/L (sensitivity 56%; specificity 72%) and a cut-off for 1-year mortality of 2.85 mmol/L (sensitivity 48%; specificity 74%). The AUC for in-hospital and 1-year mortality in relation to lactic acid levels measured postoperatively on arrival at the intensive care unit was 0.582 and 0.498, respectively. Conclusion: Although hyperlactemia in aTAAD indicates an increased risk of postoperative mortality, the sole use of lactic acid levels as a tool for accurate assessment of postoperative mortality is inadvisable due to its poor discriminatory performance.