Unfortunately, many EDs are confronted with a large number of patients with suspected ACS that can neither be classified as rule-out nor rule-in and require more observation time for additional troponin testing and diagnostic workup. This observe zone comprises 25-40% of suspected ACS patients and is essentially characterized by stable elevation of hs-cTn indicating underlying structural heart disease, CAD, or both, mirrors other relevant comorbidities and thus reflects increased individual risk. While 30-days´mortality is not very different from patients in the rule-out category, mortality at 12 months is at least as high as mortality in the rule-in category6. Other biomarkers including Copeptin, NT-pro BNP and D-Dimers have been found to provide additional and independent prognostic (all biomarkers) and diagnostic information (NT-pro BNP and D-dimers) that might help to identify the relevant pathomechanism leading to index ED admission and individualize risk assessment.