Short stay unit (SSU) is an alternative to conventional hospitalization in patients with acute heart failure (AHF), but the prognosis is not known compared to direct discharge from the emergency department (ED). To determine whether direct discharge from the ED of patients diagnosed with AHF is associated with early adverse outcomes versus hospitalization in SSU. Endpoints, defined as 30-day all-cause mortality or post-discharge adverse events, were evaluated in patients diagnosed with AHF in 17 Spanish EDs with an SSU, and compared by ED discharge vs. SSU hospitalization. Endpoint risk was adjusted for baseline and AHF episode characteristics and in patients matched by propensity score (PS) for SSU hospitalization. Overall, 2358 patients were discharged home and 2003 were hospitalized in SSUs. Discharged patients were younger, more frequently men, with fewer comorbidities, had better baseline status, less infection, rapid atrial fibrillation and hypertensive emergency as the AHF trigger, and had a lower severity of AHF episode. While their 30-day mortality rate was lower than in patients hospitalized in SSU (4.4% vs. 8.1%,p< 0.001), 30-day post-discharge adverse events were similar (27.2% vs. 28.4%,p= 0.599). After adjustment, there were no differences in the 30-day risk of mortality of discharged patients (adjusted HR 0.846, 95% CI 0.637–1.107) or adverse events (1.035, 0.914–1.173). In 337 pairs of PS-matched patients, there were no differences in mortality or risk of adverse event between patients directly discharged or admitted to an SSU (0.753, 0.409–1.397; and 0.858, 0.645–1.142; respectively). Direct ED discharge of patients diagnosed with AHF provides similar outcomes compared to patients with similar characteristics and hospitalized in a SSU.