To investigate the accuracy of lung and cardiac ultrasound (LuCUS) protocol in diagnosing Acute Heart Failure (AHF) in patients who refer to Emergency Department (ED) with acute dyspnea.

This was an interventional study on adult patients, who were referred with chief complaint of undifferentiated acute dyspnea to the ED of Namazi hospital, the largest referral center in southern Iran. The intervention was LuCUS protocol, which was performed by Emergency Physicians (EPs) at the bedside. All patients' files were reviewed separately by two independent specialists, who were blinded to LuCUS results for final diagnosis as gold standard, then the results of LuCUS were compared with it. All data were analyzed and diagnostic tests were calculated (α = 0.05).

In 100 patients enrolled in the study, 28% had the final diagnosis as AHF. The LuCUS protocol had the sensitivity of 64% (95%CI, 44%–81%), specificity of 97% (95%CI, 90%–100%), positive predicative value of 90% (95%CI, 69%–97%), negative predicative value of 88% (95%CI, 81%–92%), positive likelihood ratio of 23.14 (95%CI, 5.74–93.3), negative likelihood ratio of 0.37 (95%CI, 0.22–0.6), and accuracy of 88% (95%CI, 80%–94%).

LuCUS protocol can be used by EPs as a practical tool to differentiate the cardiac and non-cardiac etiologies of acute dyspnea, specifically AHF, as it is more accurate than clinical diagnosis by itself. Hence, it is recommend that while conducting further studies in order to achieve more generalizable results, EPs can employ it alongside their clinical evaluations to have a faster and more accurate diagnosis.