BackgroundThe early identification of patients with acute heart failure (AHF) is challenging as many other diseases lead to a clinical presentation with dyspnea.AimThe aim of the study was to evaluate the impact of natriuretic peptides at common HF study cut‐offs on the diagnosis of patients with dyspnea at admission.Methods and resultsFor this post hoc analysis, we analysed n = 726 European Union (EU) patients from the prospective BACH (Biomarkers in Acute Heart Failure) study. Cut‐offs were 350 ng/L (BNP), 300 pmol/L [pro‐atrial natriuretic peptide (proANP)], and 1800 ng/L (NT‐proBNP). These cut‐offs had equivalent 90 days' mortality in the EU cohort of BACH. We analysed the effect of selection using these cut‐offs on the prevalence of the gold standard diagnoses made in the BACH study and the respective mortality. The prevalence of AHF is increased from 47.5 to 75.6% (NT‐proBNP criteria) up to 79.7% (BNP criteria). With the use of the proANP criteria, 90 days' mortality of patients with AHF rose from 14 to 17% (P = 0.029). In the group with no‐AHF diagnoses, mortality rose from 10 to 25% (P < 0.001).ConclusionsThe prevalence of patients with the gold standard diagnoses of AHF among those presenting with dyspnea to the emergency department is significantly increased by the use of natriuretic peptides with common cut‐offs used in prospective HF studies. Nevertheless, in the selected groups, patients with no AHF diagnosis have the highest mortality, and therefore, the addition of a natriuretic peptide alone is insufficient to start specific therapies.