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

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