ABSTRACT: AIMS:This study aims to evaluate the incidence and impact of cardiorenal anaemia syndrome (CRAS) on all-cause mortality in acute heart failure (AHF) patients stratified by left ventricular ejection fraction (LVEF) status in the Middle East. METHODS AND RESULTS:Data were analysed from 4934 consecutive patients admitted to 47 hospitals in seven Middle Eastern countries (Saudi Arabia, Oman, Yemen, Kuwait, United Arab Emirates, Qatar, and Bahrain) with AHF from February to November 2012. CRAS was defined as AHF with estimated glomerular filtration rate of <60 mL/min and low haemoglobin (<13 g/dL for men or <12 g/dL for women). Analyses were performed using univariate and multivariate statistical techniques. The overall mean age of the cohort was 59 ± 15 years, 62% (n = 3081) were men, and 27% (n = 1319) had CRAS. Co-morbid conditions were common including hypertension (n = 3014; 61%), coronary artery disease (n = 2971; 60%), and diabetes mellitus (n = 2449; 50%). A total of 79% (n = 3576) of the patients had AHF with reduced ejection fraction (HFrEF) (LVEF < 50%). CRAS patients were associated with major bleeding (1.29% vs. 0.6%; P = 0.017), blood transfusion (10.1% vs. 3.0%; P < 0.001), higher re-admission rate for AHF at 3 months' follow-up (27.6% vs. 18.8%; P < 0.001) and at 12 months' follow-up (34.3% vs. 26.2%; P < 0.001). Multivariate logistic regression demonstrated that patients with CRAS were associated with higher odds of all-cause mortality during hospital admission [adjusted odds ratio (aOR), 2.10; 95% confidence interval (CI): 1.34-3.31; P = 0.001], at 3 months' follow-up (aOR, 1.48; 95% CI: 1.07-2.06; P = 0.018), and at 12 months' follow-up (aOR, 1.45; 95% CI: 1.12-1.87; P = 0.004). Stratified analyses showed that CRAS patients with HFrEF were associated with higher odds of all-cause mortality during hospital admission (aOR, 2.03; 95% CI: 1.20-3.45; P = 0.009) and at 12 months' follow-up (aOR, 1.42; 95% CI: 1.06-1.89; P = 0.019) but not at 3 months' follow-up (aOR, 1.43; 95% CI: 0.98-2.09; P = 0.063). However, in AHF patients with preserved ejection fraction (LVEF ? 50%), CRAS was not associated with higher odds of all-cause mortality not only during hospital admission (aOR, 2.15; 95% CI: 0.84-5.55; P = 0.113) but also at 3 months' follow-up (aOR, 1.87; 95% CI: 0.93-3.76; P = 0.078) and at 12 months' follow-up (aOR, 1.59; 95% CI: 0.91-2.76; P = 0.101). CONCLUSIONS:The incidence of CRAS was 27%. CRAS was associated with higher odds of all-cause mortality in AHF patients in the Middle East, especially in those with HFrEF.