ABC | Volume 111, Nº1, July 2018

Original Article Kalkan et al Adropin and Irisin Arq Bras Cardiol. 2018; 111(1):39-47 Figure 2 – Receiver-operating characteristic curve for discriminative value of serum adropin, irisin and BNP levels in systolic heart failure with reduced ejection fraction patients with or without cachexia. 1.0 1.0 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 0.0 0.0 Sensitivity 1 – Specificity Irisin Adropin BNP Reference Line levels and the severity of coronary artery atherosclerosis in diabetic patients. Zhang et al. 25 have presented similar results for patients with stable coronary artery disease. In another study, they have reported an important association between decreased adropin levels, high SYNTHAX scores and the severity of stable coronary artery disease. 26 Yu et al. 27 have examined the role of adropin in acute myocardial infarction (MI) and have shown that serum adropin levels were reduced in cases of acute MI. By elevating eNOS, adropin may have the potential to improve endothelial dysfunction, which has been widely reported in patients with heart failure with reduced ejection fraction, and decelerate left ventricular dysfunction in heart failure with reduced ejection fraction. 28 Lian et al. 7 have reported that an elevated level of adropin in heart failure with reduced ejection fraction was correlated with the severity of heart failure with reduced ejection fraction according to the NYHA class and BNP levels. The present study revealed similar findings and relations in cachectic patients with heart failure with reduced ejection fraction. Unlike the study by Lian et al., in which adropin levels and BMI were directly correlated with each other, there was an inverse relationship between adropin levels and BMI in cardiac cachexia in the present study, as expected. Although irisin is predominantly expressed in muscle and is directly associated with muscle mass, it can be expressed in different tissues. Brown adipose tissue is known to dissipate energy in the form of heat via activation of uncoupling protein 1. This process increases energy expenditure, reduces body weight and improves metabolic parameters, such as insulin sensitivity. In white tissue, irisin stimulates BAT-like phenotype changes via a process known as browning. Based on the aforementioned properties, irisin has been proposed as a possible novel treatment for diabetes and obesity. 29 Although some studies have reported positive correlations between irisin and BMI, others have reported contradictory results. 6,29 The present study revealed an inverse correlation between irisin and BMI. In addition, AMA, TST Table 3 – Receiver-operating characteristic curve analysis of adropin, irisin and brain natriuretic peptide (BNP) for predicting cachexia Variable AUC SE CI (95%) P value Sensitivity Specificity PPV NPV Adropin 0.770 0.052 0.668-0.872 0.0001 %77.3 %64.3 %69.4 %73.0 Irisin 0.705 0.056 0.596-0.815 0.001 75.0 %52.4 %62.3 %66.7 BNP 0.700 0.056 0.590-0.811 0.001 %72.7 %61.9 66.7 %68.4 AUC: area under the curve; SE: standard error; PPV: positive predictive value; NPV: negative predictive value. 44