BackgroundAcute coronary syndrome remains the principal cause of death, so the early diagnosis is of great importance. Cardiac troponin is the preferred biomarker for acute myocardial infarction. Cardiac chest pain immediately increased copeptin secretion. The combination of copeptin and cardiac troponin I is being suggested for early diagnosis of acute coronary syndrome. SubjectIt was done to emphasize the importance of association of copeptin, cardiac troponin I and high sensitive C reactive protein to confirm the diagnosis of acute myocardial infarction or unstable angina pectoris in patients with a cardiac chest pain. MethodThe current study enrolled 22 patients with acute myocardial infarction as group i and 33 patients with unstable angina pectoris as group ii. The third group consisted of 23 apparently healthy persons. Patients and controls were subjecting to laboratory investigations, which include the levels of copeptin, high-sensitivity cardiac troponin high sensitive C reactive protein creatine kinase MB fraction, lipid and I profile. ResultsWe found a significant increase of copeptin in group i when compared to group iii (30.01±12.92) (9.54±3.55), respectively, p value=0.000 and group ii (30.01±12.92) (11.16±4.58) respectively, p value 0.000, but a non-significant difference in group ii when compared to group iii (11.16±4.58) (9.54±3.55) respectively, p value=0.160. Also cardiac troponin I showed a significant increase in group i when compared to group ii (136.73±26.07) (11.18±3.79), p value=0.000, and group iii (136.73±26.07) (9.61±3.70) respectively, p value=0.000, but a non-significant difference between group ii (11.18±3.79), and group iii (9.61±3.70), p value=0.129. There was a positive correlation between copeptin and cardiac troponin I within group i, r=0.718, p value=0.000. ConclusionIn suspected acute coronary syndrome, determination of copeptin and cardiac troponin I provides a remarkable negative predictive value, which aids in early and safe ruling out of myocardial infarction.