Abstract Funding Acknowledgements None. Introduction Patients admitted due to acute coronary syndrome (ACS) are stratified using Killip class for the severity of the post myocardial infarction (MI) heart failure (HF). Killip class classification is mainly based on clinical examination and overt signs and symptoms are usually needed to be present. Purpose To evaluate subclinical congestion with lung ultrasound (LUS) in patients presenting with acute coronary syndrome. Methods For a period of 4 years, we recorded the patients presented to the emergency department of our hospital due to acute coronary syndrome (HF) and no symptoms or signs of heart failure (Killip class I). LUS was performed on admission and patients were classified as having either "wet lung" (>3 b-lines in at least 3 lung fields) or "dry lung". Baseline characteristcs, laboratory findings as well as the result of the coronary angiogram were alse recorded. Results 286 patients were recorded, with mean age 71,2 years, 43,35% were female and 56,6% male. 36.01% of the patients presented with ST elevation MI (STEMI) and 63.98% with non ST elevation MI (NSTEMI). 34.2% of patients were classified as having "wet lung". Of them, 63.98% were STEMI patients and 36.1% NSTEMI. 27.2% were males and 72.8% females and 64.6% older than 60 years old. 10.7% had on admission left ventricular ejection fraction (LVEF) >50% whereas 89.3 % had LVEF <50%.Finally, 12,7% were found to have 1 vessel disease, 23.4% 2 vessel disease and 63.9% 3 vessel disease. Compared to patients classified as having "dry lung", patients with "wet lung" stayed in the hospital 74 days (vs 3.2, p<0.01), and their mean troponin levels were 10721 pg/ml (vs 3254 pg/ml, p<0.01). "Wet lung" patients were found to have mean GFR 56,2 mL/min/1.73 m² (vs 86.7 mL/min/1.73 m² , p<0.05). Conclusion 34.2% of the patients admitted due to ACS Killip 1, were classified as having "wet lung" when examined with LUS, suggesting a status of subclinical congestion. These patients were most often STEMI patients, female and of older age and were found to have reduced LVEF. Compared to the "dry lung" patients had higher troponin levels and most oftenly impaired renal function. LUS could help identify these patients, that although they seem to be asymptomatic in terms of HF, they probably need closer monitoring.