Abstract

Objective: The currently available cardiac biomarkers are not sufficient to differentiate between myocardial infarction with non-obstructive coronary arteries (MINOCA) and acute coronary syndrome (ACS) without the use of coronary angiography. In this context, this study aimed to evaluate inducible nitric oxide synthase (iNOS) activity as a potential marker for the differential diagnosis of MINOCA and ACS.

Method: The study population comprised 734 consecutive patients who presented to our hospital with chest pain between July 2022 and January 2023. Leftover plasma samples collected in EDTA vials were sent for troponin T estimation within 24 hours of the onset of chest pain. Patients’ blood samples were collected into tubes for malondialdehyde (MDA), iNOS, and total sialic acid (TSA) measurements and centrifuged at 4000 g, 4 °C for 10 min, and the sera obtained as a result were kept at -25 °C until the analyses were performed.

Results: The mean age of the study population, which consisted of 648 patients [421 (65.6%) males, was 62±12] years. There were no significant difference between the MINOCA and ACS patients in MDA and homocysteine levels. Univariate logistic regression analysis revealed significant correlations between gender, age, diabetes mellitus (DM), glucose, urea, iNOS, smoking, hemoglobin, platelets, lymphocytes, monocytes, neutrophils, triglycerides, LDL-c, HDL-c, creatine, and TSA as significant predictors of MINOCA. Further analysis of these variables using multivariate logistic regression revealed that sex, age, presence of DM, glucose and urea levels, and iNOS were independent predictors of MINOCA. The iNOS level was significantly higher in patients with MINOCA than in those with ACS. The optimal iNOS cut-off value of >1372.9 pg/mL predicted MINOCA with 99.4% sensitivity and 93.7% specificity (area under the curve: 0.99, 95% confidence interval: 0.979-0.996, p<0.001).

Conclusion: iNOS activity may help distinguish between ACS and MINOCA without the need for coronary angiography.