Mid-regional pro-adrenomedullin is an independent predictor of cardiovascular outcomes in cardiac surgery, a prospective cohort study in 500 patients
Authors: Baumer U , Kazem N , Hammer A , Steinacher E , Hofer F , Koller L , Marculescu R , Laufer G , Hengstenberg C , Niessner A , Sulzgruber P 
Published: October 2024

Abstract

Background
MR-proADM (mid-regional pro-adrenomedullin) is a stable pro-peptide of Adrenomedullin, which is expressed in various cell types such as heart, lung, and renal tissue. It is a prognostic parameter for heart failure (HF) and sepsis as well as all-cause and cardiovascular (CV) mortality.

Purpose
Considering the characteristics of MR-proADM as a reliable biomarker for adverse events, we aimed to investigate the prognostic impact of MR-proADM in patients undergoing elective cardiac surgery.

Methods
We prospectively enrolled patients undergoing elective cardiac bypass and/or valve surgery at the department of cardiac surgery between May 2013 and August 2018. Blood samples were taken one day prior to surgery. MR-proADM was measured using an automated immunofluorescence assay. Patients were followed prospectively until endpoints were reached. The primary endpoint was the composite of hospitalization for heart failure (HHF) or CV mortality, the secondary endpoint was postoperative atrial fibrillation (POAF). The multivariate regression model was adjusted for age, sex, NT-proBNP, type of surgery, and CRP-level at baseline.

Results
A total of 500 patients (146 female [29.2%]; median age 69.8 years [IQR 60.6-75.5]) were followed over a median of 4.6 years (IQR 3.0–5.8). Valve surgery was performed in 214 (42.8%) patients, 160 (32%) underwent a bypass operation and 126 (25.2%) a combined valve and bypass surgery. The median MR-proADM value of the entire study population was 0.58 nmol/L (IQR: 0.44-0.79 nmol/L). Patients were stratified in risk categories based on their MR-proADM values (Low Risk ≤0.63nmol/L, Intermediate Risk 0.63-0.83nmol/L, High Risk &gt;0.84nmol/L). Patients in the highest category presented with higher rates of diabetes mellitus (p &lt;0.001), COPD (p &lt;0.001), HF (p=0.009) and either bypass surgery (p=0.039) or the combination of bypass and valve surgery (p=0.008), compared to patients in the lowest tertile. We observed a significant increase in 5-year’s event rates for HHF/ CV Mortality in patients in higher risk groups (Low Risk 8.6% vs High Risk 37.7%, p &lt;0.001, Figure 1). The adjusted Cox regression model found that MR-pro ADM was independently associated with a risk increase for HHF/ CV Mortality (adjusted HR of 4.45, 95% CI 2.55-8.09; p&lt;0.001, Figure 2) comparing the High Risk to the Low Risk Group. A comparable risk increase could be observed in POAF, with an adjusted HR of 2.61 (High Risk Group vs Low Risk Group, 95% CI 1.46-4.67, p&lt;0.001).

Conclusion
Within the prospective investigation, MR-pro ADM was found to be an independent predictor for HHF and CV mortality in patients undergoing cardiac bypass and/or valve surgery. Furthermore, there was a consistent predictive potential for POAF. In the era of personalized medicine, preoperative MR-pro ADM levels could help to identify patients at risk for serious adverse events, in order to apply intensified secondary prevention and reduce mortality and morbidity.