Abstract 2360: Central Sleep Apnea with Nocturnal Hypoxia Promotes Increased Circulating Erythropoietin in Heart Failure
Central sleep apnea (CSA) with nocturnal hypoxia is frequent in heart failure (HF). Hypoxia causes increased circulating erythropoietin (EPO) in healthy normals. EPO promotes increased vasoconstriction and exogenous EPO administration is associated with adverse cardiovascular events. No prior studies have related EPO concentration to apnea or hypoxia due to CSA. EPO is elevated in HF patients with nocturnal hypoxia due to CSA. Ambulatory, non-anemic HF patients (n = 29) with LVEF < 45% and healthy controls (n = 18) underwent polysomnography (PSG). Subjects with obstructive sleep apnea (OSA) were excluded. CSA was defined as apnea-hypopnea index (AHI) ≥ 15. Hypoxia was quantified as the proportion of sleep with arterial oxygen saturation < 90% (T90%). Blood for EPO was drawn post-PSG. Other clinical characteristics were summarized from the medical record. HF subjects and controls were similar age (54 vs 60 y, p = 0.09). CSA was present in 14 HF subjects; 13 were men compared to 8 of 15 without CSA (p = 0.04). HF subjects had 42% higher mean EPO than controls (p < 0.01) despite similar hemoglobin (13.9 vs 14.0 g/dL, p = 0.8). NYHA class III–IV HF subjects had 42% higher mean EPO than class I–II HF subjects (p = 0.05, figure⇓). EPO concentration was correlated with severity of nocturnal hypoxia by simple linear regression (r = 0.4; p = 0.02). By multivariate analysis, elevated EPO was associated with NYHA class III–IV HF and elevated AHI (p = 0.01 and 0.03, respectively; r = 0.6) after adjusting for age, gender, LVEF, renal function and hemoglobin. Nocturnal hypoxia due to CSA promotes increased endogenous EPO concentration in HF patients.