Indirect detection of cardiac markers for assessing acute myocardial infarction

Assay systems and methods are provided for detecting a target antigen in a physiological fluid (e.g., blood, serum, or urine). The method includes linking via a first antibody a magnetic microparticle to the target antigen in the physiological fluid; linking via a second antibody a glucose molecule to the target antigen; utilizing a magnetic field to separate the magnetic microparticle-linked antigen from the physiological fluid to form a test sample; and detecting the glucose in the test sample to determine the concentration of target antigen in the physiological fluid. The target antigen can be a protein or marker resulting from cardiac tissue injury, which can be used to assess acute myocardial infarction. An exemplary target antigen is myoglobin. The glucose detection preferably is one that can be done rapidly, e.g., with a conventional glucometer, and may include measuring the electrical resistance, color, or pH of the test sample.