Inotropes and β-blockers:: Is there a need for new guidelines?

beta -Adrenergic blocking agents are standard treatment for patients with mild-to-moderate heart failure. When patients receiving beta -blockers decompensate they often need treatment with a positive inotropic agent. The beta -agonist dobutamine may not produce much increase in cardiac output during full-dose beta -blocker treatment and may increase systemic vascular resistance via a-adrenergic stimulation. In contrast, phosphodiesterase inhibitors (PDEIs) such as milrinone or enoximone retain full hemodynamic effects during complete beta -blockade because the site of action of PDEIs is beyond the beta -adrenergic receptor and because beta -blockade reverses some of the desensitization phenomena that account for the attenuation of PDEI response in heart failure related to upregulation in G(alphai). Inotrope-requiring subjects with decompensated heart failure who are undergoing long-term therapy with beta -blocking agents should be treated with a type III-specific PDEI, not a beta -agonist such as dobutamine.