The present invention relates to the identification of a novel biomarker for cardiac ischemia: nitrated cardiac troponin I. The present invention also provides methods for the identification and use of a nitrated cardiac troponin as a biomarker for the diagnosis, prognosis and treatment management of myocardial ischemia, with and without necrosis of heart muscle.Diagnosis and prognosis is conducted by determining the amount of nitrated cardiac troponin I in serum samples of subjects and the ratio of nitrated cardiac troponin I to non-nitrated cardiac troponin I in serum samples of subjects. This biomarker can be detected by immunoassay techniques and tandem mass spectrometry. The present invention further relates to peptides, antibodies, compositions, methods, techniques, tests and kits for the identification and quantification of nitrated cardiac troponin I in samples of subjects.