Recent findings have suggested glycosylated apolipoprotein J (ApoJ-Glyc) levels to be a marker for the diagnosis of myocardial ischemia. Analysis of this marker was performed in a cohort of patients with chest pain suggestive of acute coronary syndrome (ACS) (N=404). ApoJ-Glyc serum levels were analyzed with a novel ELISA assay that targets a specific glycosylated variant of ApoJ (ApoJ-GlycA6). It was found that 291 patients were diagnosed as having a nonischemic event, while 113 were classified as having an ischemic event, 33 as STEMI, 48 as non-STEMI, 27 as unstable angina pectoris and 5 as unclassifiable ACS patients.