This advanced quantitative laboratory assay measures serum cardiac troponin I (cTnI) concentration using a new generation of high-sensitivity, high-sensitivity immunoassays. This technique allows for the measurement of troponin levels at very low concentrations (even less than 0.01 ng/mL) that conventional assays cannot detect. It enables early detection of cardiac damage, more reliable exclusion of heart attack within hours, and assessment of long-term cardiac risk even in seemingly healthy individuals.