Prediction of 6-Month Mortality Using Pre-Extracorporeal Membrane Oxygenation Lactate in Patients with Acute Coronary Syndrome Undergoing Veno-Arterial-Extracorporeal Membrane Oxygenation

Abstract

Background: The effectiveness of extracorporeal membrane oxygenation (ECMO) for patients with refractory cardiogenic shock or cardiac arrest is being established, and serum lactate is well known as a biomarker of end-organ perfusion. We evaluated the efficacy of pre-ECMO lactate for predicting 6-month survival in patients with acute coronary syndrome (ACS) undergoing ECMO.

Methods: We reviewed the medical records of 148 patients who underwent veno-arterial (VA) ECMO for ACS between January 2015 and June 2020. These patients were divided into survivors and non-survivors based on 6-month survival. All clinical data before and during ECMO were compared between the 2 groups.

Results: Patients' mean age was 66.0±10.5 years, and 116 (78.4%) were men. The total survival rate was 45.9% (n=68). Cox regression analysis showed that the pre-ECMO lactate level was an independent predictor of 6-month mortality (hazard ratio, 1.210; 95% confidence interval [CI], 1.064-1.376; p=0.004). The area under the receiver operating characteristic curve of pre-ECMO lactate was 0.64 (95% CI, 0.56-0.72; p=0.002; cut-off value=9.8 mmol/L). Kaplan-Meier survival analysis showed that the cumulative survival rate at 6 months was significantly higher among patients with a pre-ECMO lactate level of 9.8 mmol/L or less than among those with a level exceeding 9.8 mmol/L (57.3% vs. 31.8%, p=0.0008).

Conclusion: A pre-ECMO lactate of 9.8 mmol/L or less may predict a favorable outcome at 6 months in ACS patients undergoing VA-ECMO. Further research aiming to improve the accuracy of predictions of reversibility in patients with high pre-ECMO lactate levels is essential.

Keywords: Acute coronary syndrome; Cardiogenic shock; Extracorporeal membrane oxygenation; Lactic acid.

Fig. 1

Receiver operating characteristic (ROC) curve of pre-extracorporeal membrane oxygenation (ECMO) lactate levels for the prediction of 6-month mortality. The area under the ROC curve of pre-ECMO lactate levels was 0.64 (standard error=0.05; 95% confidence interval, 0.56–0.72; p=0.002, cut-off value=9.8 mmol/L). AUC, area under ROC curve.

Fig. 2

Comparison of receiver operating characteristic (ROC) curves between pre-extracorporeal membrane oxygenation (ECMO) lactate levels and Survival After Veno-Arterial Extracorporeal Membrane Oxygenation (SAVE) scores for the prediction of 6-month mortality with and without extracorporeal cardiopulmonary resuscitation (ECPR). (A) Comparison of ROC curves in all patients (difference between areas=0.06; standard error [SE]=0.06; 95% confidence interval [CI], 0.06–0.17; p=0.342). (B) Comparison of ROC curves in non-ECPR patients (difference between areas=0.03; SE=0.08; 95% CI, 0.13–0.20; p=0.643). (C) Comparison of ROC curves in ECPR patients (difference between areas=0.2; SE=0.09; 95% CI, 0.02–0.38; p=0.031). AUC, area under ROC curve.

Fig. 3

Survival analysis with cumulative mortality incidence from the time of extracorporeal membrane oxygenation (ECMO) initiation. Patients with pre-ECMO lactate levels of more than 9.8 mmol/L had a lower survival probability (p<0.0008) than patients with pre-ECMO lactate levels of less than 9.8 mmol/L.