background: performing a coronary angiography in patients with heart failure of unknown etiology is often justified by the diagnostic assessment of ischemic heart disease. however, the clinical benefit of this strategy is not known. objective: to evaluate the prevalence of ischemic heart disease by angiographic criteria in patients with heart failure and reduced ejection fraction of unknown etiology, as well as its impact on therapy decisions. methods: consecutive outpatients with heart failure and systolic dysfunction, who had an indication for coronary angiography to clarify the etiology of heart disease were assessed from 1 january 2009 to december 31, 2010. patients diagnosed with coronary artery disease, positive serology for chagas disease, congenital heart disease, valve disease or patients undergoing cardiac transplantation were excluded from the analysis. the sample was divided into two groups according to the indication for catheterization. group-1: symptomatic due to angina or heart failure. group-2: presence of > 2 risk factors for coronary artery disease results: one hundred and seven patients were included in the analysis, with 51 (47.7%) patients in group 1 and 56 (52.3%) in group 2. the prevalence of ischemic heart disease was 9.3% (10 patients), and all belonged to group 1 (p = 0.0001). during follow-up, only 4 (3.7%) were referred for cabg; 3 (2.8%) patients had procedure-related complications. conclusion: in our study, coronary angiography in patients with heart failure and systolic dysfunction of unknown etiology, although supported by current guidelines, did not show benefits when performed only due to the presence of risk factors for coronary artery disease.