High lactate levels are predictors of major complications after cardiac surgery

Abstract

Objective: Although hyperlactatemia after cardiac surgery is common, the implications of raised levels remain controversial. The aim of this study was to evaluate whether high lactate levels after cardiac surgery are predictors of major complications including mortality.

Patients and methods: This was a substudy of TRACS (Transfusion Requirements After Cardiac Surgery), which was designed as a prospective, randomized, controlled trial evaluating the effects of a transfusion strategy on morbidity and mortality.

Results: Of the 502 patients enrolled, 52 (10%) had at least 1 major complication. Patients with complications were older, had a higher EuroSCORE, lower left ventricular ejection fraction, lower preoperative hemoglobin, a higher prevalence of renal disease, and received more blood transfusions than the group without complications. Lactate levels were higher in the group with complications at the end of surgery (3.6 mmol/L [2.8-5.1] vs 3.3 mmol/L [2.2-4.8]; P = .018), immediately after intensive care unit (ICU) admission (0 hour) (4.4 mmol/L [3.1-8.4] vs 4 mmol/L [2.6-6.4]; P = .048); 6 hours (4 mmol/L [2.7-5.8] vs 2.6 mmol/L [2-3.6], P < .001), and 12 hours after admission (2.3 mmol/L [1.8-3.2] vs 1.7 mmol/L [1.3-2]; P < .001). In a multivariate model, higher age (odds ratio [OR], 1.048, 95% confidence interval [CI], 1.011-1.086; P = .010), left ventricular ejection fraction (LVEF) lower than 40% (OR, 3.03; 95% CI, 1.200-7.510; P = .019 compared with LVEF of 40%-59%; OR, 3.571; 95% CI, 1.503-8.196; P = .004 compared with LVEF higher than 60%), higher EuroSCORE (OR, 1.138; 95% CI; 1.007-1.285; P = .038), red blood cell transfusion (OR, 1.230; 95% CI, 1.086-1.393; P = .001), and lactate levels 6 hours after ICU admission (OR, 3.28, 95% CI; 1.61-6.69; P = .001) are predictors of major complications.

Conclusions: Hyperlactatemia 6 hours after ICU admission is an independent risk factor for worse outcomes in adult patients after cardiac surgery.

Trial registration: ClinicalTrials.gov NCT01021631.

Keywords: 16; 18; 21; 23; ARDS; CI; CPB; ICU; LVEF; OR; RIFLE; ROC; TRACS; Transfusion Requirements After Cardiac Surgery; adult respiratory distress syndrome; cardiopulmonary bypass; confidence interval; intensive care unit; left ventricular ejection fraction; odds ratio; receiver operating characteristic; renal risk, injury, failure, loss, end-stage kidney disease.