Background: Delirium is a common, life-threatening, typical clinical syndrome with the main clinical manifestations of temporary organic mental disorder without specific drug treatment. The aim of the study was to explore the benefits of melatonin for the treatment of delirium after acute heart failure in elderly patients.

Methods: This was a randomized, double-blind, and placebo-controlled trial. This study enrolled patients aged more than 60 years after acute heart failure. A computer-generated randomization sequence (in a 1:1 ratio) was used to randomly assign patients to receive either melatonin (3 mg/day, 7 days) or placebos. The primary endpoint was the incidence of delirium, assessed twice daily with the Confusion Assessment Method during the first 7 days. Analyses were performed by intention-to-treat and safety populations.

Results: Between October 2015 and October 2019, 584 patients were assessed. A total of 497 patients randomly were assigned to receive either placebo (N = 249) or melatonin (N = 248). The incidence of delirium was significantly lower in the melatonin group than in the placebo group (27.0% vs. 36.9%, P = 0.021). Regarding safety, the occurrence of rhabdomyolysis and abnormal hepatic function did not differ between the two groups.

Conclusion: The current study (clinical trial registered number: CHWX-904-201511) suggests that acute melatonin treatment can reduce the incidence of delirium for elderly acute heart failure. It also can reduce the time of hospital stays and hospitalization costs. The therapy was safe and worth spreading.