The search and development of new drug categories In heart failure, particularly acute decompensation, is still ongoing. RELAX-AHF-2 trial assessed the Use of serelaxin compared with placebo in patients with acute heart failure. Adding this drug to standard medication of the disease did not clinically improve symptoms up to the fifth day of hospitalization nor did it decrease cardiovascular mortality of patients up to 180 days. The decrease in all-cause mortality up to 180 days and the shortening of hospitalization stay was not achieved as well. The drug was well-tolerated, adverse effects were comparable with placebo.