Acute and long-term hemodynamic response to low-dose enoximone in refractory heart failure

Enoximone possesses both positive inotropic and vasodilatory properties. In heart failure, doses varying between 3 mg/kg and 6 mg/kg produce a beneficial acute hemodynamic response but have been associated with significant side effects. Little is known about the long-term hemodynamic efficacy of this agent. To assess whether a lower dose of enoximone could produce both acute and long-term hemodynamic benefits and be better tolerated, 15 patients with refractory heart failure were given enoximone 100 mg every 8 hours (mean dose, 1.7 mg/kg). The cardiac index, pulmonary capillary wedge pressure, pulmonary artery pressure, right atrial pressure, systemic vascular resistance, pulmonary vascular resistance, and stroke volume index all improved significantly during the first 24 hours. The systemic blood pressure and heart rate did not alter appreciably during this period. Five of six patients remaining on therapy at 6 months had a follow-up hemodynamic study. Sustained improvement was seen in the cardiac index, pulmonary capillary wedge pressure, and pulmonary artery pressure when compared to baseline (all p less than 0.05). A satisfactory trend, which did not reach statistical significance, was noted in the right atrial pressure (p = 0.09) and stroke volume index (p = 0.06). Diarrhea occurred in one patient. These findings indicate that enoximone has a beneficial acute and long-term hemodynamic effect at a low dose that is clinically well tolerated.