Administration of an HNO/NO^- donating compound, such as Angeli's salt, increases myocardial contractility while concomitantly lowering left ventricular preload in subjects experiencing heart failure Moreover, administration of the HNO/NO^- donating compound isopropylamine (IPA)/NO (Na(CH₃)₂CHNHN(O)NO) surprisingly exhibited positive inotropic effects in subjects experiencing heart failure that were superior to those caused by the HNO/NO^- donating compound Angeli's salt. Additionally, in contrast to the effects observed with NO^- donors, administration of an HNO/NO^- donor in combination with a positive inotropic agent did not impair the positive inotropic effect of the positive inotropic agent Further, HNO/NO^- exerts its positive inotropic effect independent of the adrenergic system, increasing contractility even in subjects receiving beta-antagonist therapy