[New positive inotropic drugs in acute and chronic heart failure]

Beta-adrenergic stimulants (Dobutamine and Dopamine) and recently introduced phosphodiesterase inhibitors (PDI) such as Amrinone, Milrinone, Enoximone and Piroximone are the principal inotropic agents for the treatment of acute cardiac failure. Most of the hemodynamic effects of these drugs are comparable, but peripheral vasodilatation is more marked with PDI. A potential advantage of the latter group is the lack of development tolerance, which occurs within 48 to 72 hours after beta-stimulants. On simultaneous administration, additive effects can be observed. Short term clinical results with PDI are good, especially in patients with postoperative cardiocirculatory failure, including cardiogenic shock. In contrast, long-term oral treatment with Amrinone, Milrinone and Enoximone in recent studies was disappointing. Efficacy was not superior to Digoxin, and unwanted side effects were frequent. Intermittent instead of continuous administration of positive inotropic agents should be evaluated in patients with severe congestive heart failure not responding to vasodilators and diuretics.