Objectives: To investigate the characteristics of the acute coronary syndromes underlying acute pulmonary oedema and their 30 day prognosis. Patients: 185 consecutive patients with acute coronary syndromes and acute pulmonary oedema admitted to a tertiary care centre. Main outcome and measures: Clinical, ECG, echocardiographic, enzymatic, and angiographic features were prospectively investigated. Results: Non-ST segment elevation myocardial infarction(NSTEMI) was the most frequent cause of acute pulmonary oedema(61%) followed by unstable angina(UA; 21%) and ST segment elevation myocardial infarction(STEMI; 18%). In each group, mean age was ≥70 years, but NSTEMI patients were the oldest and ≥65%of patients had chronic hypertension. Moreover, patients with NSTEMI and UA were older and had a higher incidence of diabetes, previous myocardial infarction, and moderate to severe mitral regurgitation but a similarly reduced ejection fraction(NSTEMI, 41%; UA, 39%; and STEMI, 39%) and increased incidence of diastolic dysfunction and rate of multivessel disease(94%, 87%, and 86%, respectively). However, patients with STEMI had a higher creatine kinase MB peak concentration(158 v 76 μg/l in the NSTEMI group, p< 0.001) and 30 day mortality(26%v 9%in the NSTEMI group and 8%in the UA group, p< 0.024). Multivariate analysis identified ejection fraction< 40%and a peak creatine kinase MB concentration >100 μg/l as the main prognostic markers(p< 0.03). Conclusions: Acute pulmonary oedema is mostly a complication of elderly hypertensive patients with NSTEMI or UA(82%) and with multivessel disease often associated with mitral regurgitation. On the other hand, the larger infarct size and higher mortality in patients with STEMI with a similarly reduced ejection fraction suggest a more extensive acute systolic loss. Objectives: To investigate the characteristics of the acute coronary syndromes underlying acute pulmonary odema and their 30 day prognosis. Patients: 185 consecutive patients with acute coronary syndromes and acute pulmonary oedema admitted to a tertiary care center. Main outcome and measures: Clinical, ECG, Results: Non-ST segment elevation myocardial infarction (NSTEMI) was the most frequent cause of acute pulmonary oedema (61%) followed by unstable angina (UA; 21%) and ST segment elevation Myocardial infarction (STEMI; 18%). In each group, mean age was ≥70 years, but NSTEMI patients were the oldest and ≥65% of patients had chronic hypertension. of diabetes, previous myocardial infarction, and moderate to severe mitral regurgitation but significantly reduced ejection fraction (NSTEMI, 41%; UA, 39%; and STEMI, 39%) and increa sed incidence of diastolic dysfunction and rate of multivessel disease (94%, 87%, and 86%, respectively). However, patients with STEMI had a higher creatine kinase MB peak concentration (158 v 76 μg / l in the NSTEMI group, p <0.001) and 30 day mortality (26% v 9% in the NSTEMI group and 8% in the UA group, p <0.024) Multivariate analysis identified ejection fraction <40% and a peak creatine kinase MB concentration> 100 μg / l as the main prognostic markers (p <0.03). Conclusions: Acute pulmonary oedema is mostly a complication of elderly hypertensive patients with NSTEMI or UA (82%) and with multivessel disease often associated with mitral regurgitation. On the other hand, the larger infarct size and higher mortality in patients with STEMI with very reduced ejection fraction suggest a more extensive acute systolic loss.