Inducible Nitric Oxide Synthase Expression is a Potential Marker for Acute Coronary Syndrome: A Preliminary Study

Background: In acute coronary syndrome (ACS), nitric oxide is generated in excess during ischemic attack due to marked activation of the inducible nitric oxide synthase (iNOS) enzyme by different cytokines. Consequently, serious damaging effects result. Objective: To explore the potential role of iNOS mRNA expression as a marker of acute ischemia in ACS patients and as a predictor of the attack outcome. Method: Forty-eight ACS patients and 24 healthy volunteers were enrolled in the study. Cardiac markers were assessed, including creatine kinase (CK), CK-MB and troponin T. RNA was extracted from peripheral blood and iNOS mRNA was quantified by reverse transcription and real-time PCR (RT-PCR). Results: iNOS mRNA relative expression was significantly elevated in ACS patients compared to healthy subjects (p < 0.001) and was lower in patients with good outcome than those with bad outcome (p = 0.029). ROC curve discriminated between ACS patients and controls (AUROC curve: 1; p < 0.001) with 100% sensitivity and specificity at a cutoff value of 38.5. iNOS expression in ACS patients with normal troponin T (66.7%) and those with elevated levels were comparable (p = 0.24). In addition, iNOS expression showed no correlation with CK and CK-MB levels. Conclusion: The estimation of iNOS mRNA expression is an applicable, sensitive and specific assay for ACS diagnosis. Low mRNA levels correlate with good outcome of the acute ischemic attack. However, further study on larger sample size can validate these findings.