Characterisation of plasma proteins and circulating microRNAs in out-of-hospital cardiac arrest patients - approaches for predicting outcome

Abstract Rationale: Early prognostication after out-of-hospital cardiac arrest (OHCA) is an unmet clinical need. There is limited data on serial release kinetics of cardiac, brain and systemic biomarkers such as Neuron Specific Enolase (NSE) and S-100B. miRNAs are sensitive biomarker candidates in acute myocardial infarction (MI). Objective The objective was to characterise circulating biomolecules in the early release kinetics after OHCA, compared with a STEMI control group and assessed with clinical outcome. Methods and Results Serial blood samples of patients with OHCA with STEMI (n=20) and STEMI control (n=20) were collected at baseline and at 6, 12, 24 and 48h after admission. Untargeted plasma proteomics were performed using data-independent acquisition–mass spectrometry (DIA–MS). Candidate proteins and miRNAs were quantified. Proteomics returned n=156 proteins with significantly different kinetics between OHCA and STEMI. Six clusters, depicting distinct biological pathways, with characteristic differences between OHCA and STEMI were identified. The most distinct and significant differences between OHCA and STEMI patients were seen for acute phase reactants LBP, AACT, CRP and the lipid metabolite A2GL as well as endothelial and platelet miR-126 and cardiomyocyte-apoptosis/ischemia-reperfusion related miR-320a. Cardiogenic shock was best characterised by differential kinetics of coagulation and complement related proteins FA9, HRG, FHR1 and inflammation related miR-146. The primary endpoint was poor neurological recovery at 30-days. Individuals with good outcome showed distinct differences in adaptive immune response, complement and coagulation cascades and hemostasis. Circulating plasma levels of hypoxia-associated miR-101, miR-210 and S-100B protein were significantly elevated at baseline in OHCA patients. These molecules further showed higher baseline values in patients with poor outcome. For current prognosis marker NSE, this difference only develops after 48h. Cardiac/muscle miRNAs followed an early release-pattern similar to high-sensitivity cardiac troponin-T (hs-cTnT). Machine learning models were used to calculate the AUC for the prediction of poor neurological outcome at baseline. This was highest for hypoxia-induced miR-210 (AUC: 0.854), which performed significantly better than the protein biomarkers NSE (AUC: 0.646) and S-100B (AUC:0.656). Conclusions Untargeted mass spectrometry reveals distinct biological pathways and candidate biomolecules affected in patients suffering from OHCA compared with STEMI controls, in patients developing cardiogenic shock and in those with adverse versus good neurological outcome. Platelet-, inflammation and hypoxia associated miRNAs are associated with OHCA, cardiogenic shock and prognostication of adverse neurological outcome. Pronounced differences in early release kinetics of RNA and protein biomarkers may improve identification of OHCA patients at risk of poor outcome.