Association Between Urinary 6-Sulfatoxymelatonin and Cardiac Stress Biomarkers in Patients Scheduled for Coronary Artery Bypass Grafting

Coronary artery bypass grafting (CABG) serves as an essential intervention for patients exhibiting severe coronary artery disease; however, oxidative stress and disturbances in circadian rhythms may adversely affect patient outcomes. This research examined the interrelations among cardiac biomarkers, indicators of oxidative stress, and urinary 6-sulfatoxymelatonin (6-SMT), major urinary metabolite of melatonin, in individuals scheduled for CABG in comparison to healthy control subjects. A total of sixty patients undergoing CABG and thirty control participants were assessed for serum cardiac markers, including troponin, CK-MB, and NT-proBNP, oxidative stress markers such as oxLDL, inflammatory cytokines (IL-6 and CRP), cortisol levels, and urinary 6-SMT concentrations. The results revealed significantly lower levels of 6-SMT and oxLDL, along with elevated levels of cardiac and inflammatory biomarkers among CABG patients. Furthermore, sleep quality exhibited a negative correlation with inflammatory markers and a positive correlation with indicators of oxidative stress. These findings suggest that melatonin deficiency and disrupted circadian rhythms may play a role in myocardial stress and systemic inflammation in patients before CABG, underscoring the potential of 6-SMT as a non-invasive biomarker for assessing cardiovascular risk and guiding therapeutic interventions.