Abstract Background An appropriate diagnostic process is crucial for managing patients with acute heart failure (AHF) in emergency department (ED). Our study aims to describe the characteristics and therapeutic management of patients admitted to the ED for dyspnea suspected to have AHF, their in-hospital pathway of care and their in-hospital outcome. Methods Consecutive patients admitted in 26 French ED for dyspnea suspected to be the consequence of AHF, prior to in hospital diagnostic test, were prospectively included at the time of their admission in the DeFSSICA Survey. Clinical characteristics at admission were recorded by the ED physicians. At discharge from ED, patients were categorized as AHF or non-AHF based on the final diagnosis reported in the discharge summary. The completeness of the data was controlled by the local investigator. Results From 16/6/2014 to 7/7/2014, 699 patients were included, of whom 537 (77 %) had a final diagnosis of AHF at discharge. Patients with AHF were older (median 83 vs 79 years, p = 0.0007), more likely to have hypertension (71 % vs 57 %, p = 0.002), chronic HF (54 % vs 37 %, p = 0.0004), atrial fibrillation (45 % vs 34 %, p = 0.02) and history of hospitalization for AHF in the previous year (40 % vs 18 %, p 90 % in DeFSSICA. Similarly, BNP or pro-BNP was measured in 93 % of patients, compared with 82 % of patients in the OFICA study. Although BNP may be helpful when the diagnosis of HF is in doubt, ultrasound remains the gold standard. The use of ultrasound in the ED has been reported to accelerate the diagnosis of HF and the initiation of treatment, and shorten the length of stay. In-hospital mortality of HF patients in DeFSSICA was 6.4 %, slightly lower than in the OFICA study (8.2 %). Improved interdisciplinary cooperation has been highlighted as a key factor for the improvement of HF patient care. Conclusions DeFSSICA shows that patients admitted for dyspnea suspected to be the consequence of AHF are mostly elderly. The diagnosis of AHF is difficult to ascertain based on clinical presentation in patients with dyspnea. Novel diagnostic techniques such as thoracic ultrasound are warranted to provide the right treatment to the right patients in the ED as early as possible.