Milrinone versus dobutamine in heart failure subjects treated chronically with carvedilol

Objective: To compare the efficacy of milrinone and dobutamine in patients chronically treated with carvedilol. Background: Milrinone and dobutamine are used to manage decompensated heart failure, but their efficacy in patients on beta-blocker therapy was unknown. Methods: Twenty patients with decompensated heart failure were prospectively enrolled. Inotropic responses to milrinone (12.5, 25 or 50 μg/kg bolus infusions) or dobutamine (5, 10, 15 or 20 μg/kg/min infusions) were evaluated by right-heart catheterization. Results: Milrinone increased cardiac index (2.0–2.6 l/min/m2, P=0.0001) without significantly altering heart rate (70–75 bpm, P=0.19). Milrinone decreased mean pulmonary artery pressure (36–29 mm Hg, P=0.0001), pulmonary capillary wedge pressure (24–18 mm Hg, P=0.0001) and mean arterial blood pressure (78–75 mm Hg, P=0.0002). Left ventricular stroke volume index increased in the milrinone group (31–35 ml/beat/m2, P=0.0001). Dobutamine produced an increase in cardiac index (2.4–3.3 l/min/m2, P=0.0001) only at doses that are not typically used to treat heart failure (15–20 μg/kg/min). At these doses, dobutamine increased heart rate (68–82 bpm, P=0.008), mean systemic pressure (90–117 mm Hg, P=0.0001) and mean pulmonary artery pressure (21–30 mm Hg, P=0.001). Dobutamine did not alter left ventricular stroke volume index or pulmonary capillary wedge pressure. Conclusions: Dobutamine and milrinone have different hemodynamic effects in patients treated chronically with carvedilol. These differences should be considered when selecting inotropic therapy for decompensated heart failure.