Aims: To investigate the clinical characteristics of obstructive sleep apnea syndrome in patients with heart failure (HF).
 Patients and Methods: From 9/2020 to 9/2021, patients with chronic HF (European Society of Cardiology’s criteria) and obstructive sleep apnea (American Academy of Sleep Medicine’s criteria) were enrolled into the study. Clinical examination, blood test, echocardiography, polysomnography, ventilatory polygraphy were performed in all patients.
 Results: 63 patients were included: 54 male (85.7%), 9 female (14.3%), age 69.57 ± 13.08, BMI 28.63 ± 4.16 kg/m2, neck size >40 cm: 69.3%, 100% male and 88.9% female had waist circumference ≥90 cm, hypertension 78.4%, diabetes 47.6%, HFrEF 12 (18%), HFmrEF 5 (7.9%), HFpEF 46 (73%). 68.3% patients had Epworth ≥10, snoring 92.1%. Compared to patients with apnea-hypopnea index (AHI) <15 and AHI 15-30, patients with AHI>30 had thicker interventricular septum, higher left ventricular mass (LVM) and LVM index, lower e’ velocity, higher E/e’ ratio, higher left atrial volume index, higher systolic artery pulmonary pressure, p<0.05. Multivariate regression showed that age, body mass index, neck size, HbA1C were independent predictors of high AHI, p<0.05.
 Conclusions: Majority of patients with chronic HF and obstructive sleep apnea were male, old age, overweight/obesity, and had large neck size. Hypertension and diabetes and heart failure with preserved ejection fraction were prevalent. Patients with AHI>30 had higher interventricular septal thickness, higher LVM and LVM index, lower e’ velocity, higher E/e’ ratio, higher left atrial volume index, higher systolic artery pulmonary pressure, p<0.05. Age, body mass index, neck size, HbA1C were independent predictors of high AHI, p<0.05.