AbstractAimsThe presence of accompanying dyspnoea is routinely assessed and common in patients presenting with acute chest pain/discomfort to the emergency department (ED). We aimed to assess the association of accompanying dyspnoea with differential diagnoses, diagnostic work-up, and outcome.Methods and resultsWe enrolled patients presenting to the ED with chest pain/discomfort. Final diagnoses were adjudicated by independent cardiologists using all information including cardiac imaging. The primary diagnostic endpoint was the final diagnosis. The secondary diagnostic endpoint was the performance of high-sensitivity cardiac troponin (hs-cTn) and the European Society of Cardiology (ESC) 0/1h-algorithms for the diagnosis of myocardial infarction (MI). The prognostic endpoints were cardiovascular and all-cause mortality at two years. Among 6045 patients, 2892/6045 (48%) had accompanying dyspnoea. The prevalence of acute coronary syndrome (ACS) in patients with vs. without dyspnoea was comparable (MI 22.4% vs. 21.9%,P= 0.60, unstable angina 8.7% vs. 7.9%,P= 0.29). In contrast, patients with dyspnoea more often had cardiac, non-coronary disease (15.3% vs. 10.2%,P< 0.001). Diagnostic accuracy of hs-cTnT/I concentrations was not affected by the presence of dyspnoea (area under the curve 0.89–0.91 in both groups), and the safety of the ESC 0/1h-algorithms was maintained with negative predictive values >99.4%. Accompanying dyspnoea was an independent predictor for cardiovascular and all-cause death at two years [hazard ratio 1.813 (95% confidence intervals, 1.453–2.261,P< 0.01)].ConclusionAccompanying dyspnoea was not associated with a higher prevalence of ACS but with cardiac, non-coronary disease. While the safety of the diagnostic work-up was not affected, accompanying dyspnoea was an independent predictor for cardiovascular and all-cause death.Clinical Trial Registrationhttps://clinicaltrials.gov/ct2/show/NCT00470587, number NCT00470587