The present invention relates to the administration of nitroxyl donating compounds, such as Angeli's salt for increasing myocardial contractility while concomitantly lowering left ventricular preload in subjects experiencing heart failure. Moreover, administration of the nitroxyl donating compound, isopropylamine, surprisingly exhibits positive inotropic effects in subjects experiencing heart failure that were superior to those caused by Angeli's salt. Additionally, in contrast to the effects observed with nitric oxide donors, administration of a nitroxyl donating compound in combination with a positive inotropic agent does not impair the positive inotropic effect of the positive inotropic agent. Furthermore, nitroxyl donating compounds exert its positive inotropic effect independent of the adrenergic system, increasing contractility even in subjects receiving beta-antagonist therapy.