© 2016 Canadian Cardiovascular Society Background The role of acute arterial hypertension in acute pulmonary edema (APE) as an associated or triggering phenomenon has been poorly investigated and is relevant to patient management. Methods This was a prospective observational study of clinical, electrocardiographic, and echocardiographic characteristics of patients with APE. Potential triggers, including acute coronary syndrome (ACS), rapid atrial fibrillation (AF) (≥ 120 bpm in AF), fever > 38°C or volume overload, isolated acute hypertension (systolic blood pressure ≥ 170 mm Hg), and unknown factors were investigated. Results There were 742 patients, 578 with coronary artery disease (78%), 116 with valvular heart disease or cardiomyopathy (16%), and 47 without identifiable heart disease (6%). ACS was present in 482 (65%) patients (silent in 154 of them), AF was present in 76 (10%) patients, fever/volume overload was present in 62 (8%) patients, acute hypertension was present in 50 (7%) patients, and no apparent trigger was seen in 72 (10%) patients. Admission hypertension occurred in 260 patients (35%): 155 (60%) with ACS (silent in 49 [32%]), 36 (14%) with AF, 19 (7%) with fever/volume overload, and 59 (19%) as an isolated trigger. Similar results were obtained when analyzing patients using coronary angiography (467 patients [63%]). Acute hypertension was present more frequently in patients with severe hypoventilation (arterial PCO2 > 60 mm Hg) than in those without (57% vs 29%; P < 0.001) and in those without moderate-severe mitral regurgitation than in those with (51% vs 30%; P < 0.001). Conclusions In patients with APE, with or without ACS, acute hypertension is often present but mainly as an associated/reactive phenomenon and seems favoured by severe hypoventilation. Silent myocardial ischemia/necrosis deserves systematic investigation because it is not rare that it may be the underlying cause of APE.