Plasma levels of melatonin in dilated cardiomyopathy

BACKGROUND: Melatonin is a multifunctional indolamine and has a cardioprotective role in a variety of cardiovascular processes via antioxidant, anti‐inflammatory, antihypertensive, antithrombotic, and antilipemic effects. It has been reported that lower levels of circulating melatonin are significantly associated with a higher risk of acute myocardial infarction (AMI) and later cardiac remodeling. However, levels of melatonin in patients with dilated cardiomyopathy (DCM) and associations between melatonin levels and cardiac function remain unclear. METHODS AND RESULTS: We measured and compared plasma levels of melatonin in 61 control subjects, 81 AMI patients, and 77 DCM patients. Plasma levels of melatonin were progressively decreased from 71.9 pg/mL in the control group to 52.6 pg/mL in the DCM group and 21.9 pg/mL in the AMI group. Next, we examined associations of melatonin levels with parameters of laboratory data, echocardiography, and right‐heart catheterization. In the DCM patients, circulating melatonin showed significant correlations with both high‐sensitivity troponin T (R = −0.422, P < 0.001) and cardiac output (R = 0.431, P = 0.003), but not with B‐type natriuretic peptide (BNP), left ventricular ejection fraction (LVEF), pulmonary artery wedge pressure, or pulmonary artery pressure. CONCLUSION: Patients with not only AMI but also DCM had lower circulating melatonin levels. Circulating melatonin levels appear to correlate with myocardial injury and cardiac output in DCM patients.