Istaroxime hydrochloride is primarily used in the treatment of acute heart failure. It works by enhancing the heart's contractility and improving its relaxation, which helps in managing symptoms and stabilizing patients during critical episodes. This dual mechanism of action makes it particularly effective in situations where both inotropic (strengthening heart contractions) and lusitropic (improving heart relaxation) effects are needed. Its application is especially beneficial for patients who do not respond adequately to standard therapies, providing a potential option to improve cardiac function and reduce hospitalization rates.