A substance or reactant intended to be used together with a parent IVD to perform a specific function in an assay that is used for the qualitative and/or quantitative detection of one or a combination of cardiac markers in a clinical specimen. These cardiac markers may include B-type natriuretic protein, D-dimer, creatine kinase myocardial isoenzyme (CKMB), myoglobin, myeloperoxidase (MPO), fatty acid binding protein (FABP), glycogen phosphorylase isoenzyme BB (GPBB), troponin I and/or troponin T.