SUN-066 Circulating Irisin and Correlation with Antioxidant Systems in Different Models of Heart Failure

Irisin is a recently discovered myokine, derived from a proteolytic cleavage of the transmembrane protein Fibronectin type III-domain containing 5 (FNDC5), whose expression is induced by physical exercise. This myokine is involved in the browning of white adipose tissue, enhancing energy expenditure, granting a protection against insulin-resistance. Moreover, irisin has been considered a prognostic factor in Chronic Ischemic Cardiomyopathy and Acute Heart Failure. Nevertheless, no data are available on irisin levels in Chronic Heart Failure (CHF), both with preserved (HFpEF) or reduced (HFrEF) ejection fraction. We have evaluated circulating irisin levels, in these two subtypes of Heart Failure (HFpEF: n=22, age range 59-88 ys, mean±SEM BMI 28.9±1.3 kg/m(2), NYHA class 2-3; HFrEF: n=18, age range 42-88 ys, mean±SEM BMI 27.8±1.28 kg/m(2), NYHA class 2-3) and correlated them with echocardiographic features, metabolic parameters (HOMA-index) and Total Antioxidant Capacity (TAC), measured by spectrophotometric method, using the system H(2)O(2)-metmyoglobin, and expressed as LAG, latency time before the appearance of the radical species of the chromogen ABTS. Irisin was significantly higher in HFpEF patients (mean±SEM: 7.72±0.65 ng/ml vs 2.77±0.77 ng/ml), while TAC was higher in HFpEF, but not significantly (77.6±7.3 sec vs 69.6±4.5 sec). An inverse correlation between irisin and TAC was found in the same group (p<0.05). mean±SEM HOMA-index was 2.8±0.54 in HFpEF and 2.4±0.42 HFrEF; no correlation between irisin and HOMA was detected. No correlation between echocardiographic parameters and irisin was found both in HFpEF and HFrEF group. These data may suggest a different pathophysiological mechanism in these two subtypes of CHF, and a possible role of Oxidative Stress in modulation of irisin levels.