Lactate Clearance Is Associated With Improved Survival in Cardiogenic Shock: A Systematic Review and Meta-Analysis of Prognostic Factor Studies

Elevated blood lactate levels are strongly associated with mortality in patients with cardiogenic shock. Recent evidence suggests that the degree and rate at which blood lactate levels decrease after the initiation of treatment may be equally important in patient prognosis. We performed a systematic review and meta-analysis to evaluate the usefulness of lactate clearance as a prognostic factor in cardiogenic shock. We performed searches of Ovid MEDLINE, Elsevier EMBASE, EBM Reviews–Cochrane Central Register of Controlled Trials, and Web of Science to identify studies comparing lactate clearance between survivors and nonsurvivors at one or more timepoints. Both prospective and retrospective studies were eligible for inclusion. Two study investigators independently screened, extracted data, and assessed the quality of all included studies. Twelve studies were included in the meta-analysis. The median lactate clearance at 6–8 hours was 21.9% (interquartile range [IQR] 14.6%–42.1%) in survivors and 0.6% (IQR –3.7% to 14.6%) in nonsurvivors. At 24 hours, the median lactate clearance was 60.7% (IQR 58.1%–76.3%) and 40.3% (IQR 30.2%–55.8%) in survivors and nonsurvivors, respectively. Accordingly, the pooled mean difference in lactate clearance between survivors and nonsurvivors at 6–8 hours was 17.3% (95% CI 11.6%–23.1%, P < .001) at 6–8 hours and 27.9% (95% CI 14.1%–41.7%, P < .001) at 24 hours. Survivors had significantly greater lactate clearance at 6–8 hours and at 24 hours compared with nonsurvivors, suggesting that lactate clearance is an important prognostic marker in cardiogenic shock.