Mid-regional pro-adrenomedullin and lactate levels for risk stratification in patients with out-of-hospital cardiac arrest

Aims Adrenomedullin (ADM) is a free-circulating peptide that regulates endothelial barrier function and vascular tone. Here, we sought to study the relationship of ADM in combination with lactate and the risk of death in patients with out-of-hospital cardiac arrest (OHCA). Methods and results Mid-regional pro-adrenomedullin (MR-proADM) and lactate concentrations were measured in patients with OHCA who survived at least 24 h after the return of spontaneous circulation. The outcome of interest was all-cause death. Patients were characterized by the quartiles (Q) of MR-proADM and lactate concentrations. Cox models were adjusted for age, sex, shockable rhythm, bystander resuscitation, simplified acute physiology score II (SAPS II), and estimated glomerular filtration rate (eGFR). A total of 232 patients were included in the present study (28% women, 67 years, SAPS II 80). The median MR-proADM and lactate levels at 24 h were 1.4 nmol/L [interquartile range (IQR) 0.8–2.8 nmol/L] and 1.8 mmol/L (IQR 1.3–3.4 mmol/L), respectively. Mid-regional pro-adrenomedullin concentrations correlated weakly with lactate levels (r = 0.36, P < 0.001). High (Q4) vs. low (Q1–Q3) MR-proADM concentrations were significantly associated with an increased rate of death at 28 days (75.9 vs. 45.4%; P < 0.001). After multivariable adjustment (including lactate levels at 24 h), higher MR-proADM levels were significantly associated with an increased risk of death [Q4 vs. Q1–Q3: adjusted hazard ratio (adj-HR) 1.67, 95% confidence interval (CI) 1.12–2.50; adj-HR for a 1-unit increase in a standardized biomarker 1.44, 95% CI 1.19–1.73]. This relationship remained significant even after further adjustment for baseline NT-proBNP and high-sensitivity troponin T levels. The combination of high MR-proADM and high lactate (Q4) concentrations identified patients at a particularly elevated risk (adj-HR 3.50; 95% CI 1.92–6.39). Conclusion Higher MR-proADM concentrations are associated with an increased risk of death in patients with OHCA, and the combination of high MR-proADM and lactate levels identifies patients at a distinctly elevated risk.