Diagnostic use of serum deoxyribonuclease I activity as a novel early-phase marker in acute myocardial infarction

Background - The delayed release of serum cardiac markers such as creatine kinase isoenzyme MB and equivocal early electrocardiographic changes have hampered a diagnosis of acute myocardial infarction ( AMI) in the early phase after its onset. Therefore, a reliable serum biochemical marker for the diagnosis of AMI in the very early phase is desirable. Methods and Results - Serum samples were collected from the patients with AMI, unstable angina pectoris, stable angina pectoris, and other diseases. Levels of serum deoxyribonuclease I ( DNase I) activity in the patients were determined. An abrupt elevation of serum DNase I activity was observed within approximately 3 hours of the onset of symptoms in patients with AMI, with significantly higher activity levels (21.7 +/- 5.10 U/L) in this group compared with the other groups with unstable angina pectoris (10.4 +/- 4.41 U/L), angina pectoris (10.8 +/- 3.70 U/L), and other diseases (9.22 +/- 4.16 U/L). Levels of the DNase I activity in serum then exhibited a marked time-dependent decline within 12 hours and had returned to basal levels within 24 hours. Conclusions - We suggest that serum DNase I activity could be used as a new diagnostic marker for the early detection of AMI.