Amrinone and
milrinone are
phosphodiesterase inhibitors with positive inotropic effects useful for the treatment of
ventricular dysfunction after cardiac surgery. Forty-four patients undergoing elective cardiac surgery at four centers received either
amrinone (n = 22) or
milrinone (n = 22) in a randomized, blind fashion. Immediately after separation from
cardiopulmonary bypass (CPB), two bolus doses of either
amrinone 0.75 mg/kg or
milrinone 25 microg/kg were administered over 30 s, separated by 5 min. Hemodynamic measurements were recorded before each dose and at the end of the 10-min study. Both
amrinone and
milrinone increased the cardiac index (48% vs 52%, P = not significant [NS] for
amrinone and
milrinone, respectively). There was a small increase in mean arterial pressure (MAP) after
amrinone administration (from 68 +/- 3 to 72 +/- 3 mm Hg
at 10 min, P < 0.05) with no significant change in MAP after
milrinone administration. Central venous pressure was significantly higher in the
amrinone group at baseline and 5 min (12 vs 10 mm Hg and 11 vs 10 mm Hg, respectively; P < 0.05). Systemic and pulmonary vascular resistances decreased significantly and to a similar extent after either
amrinone or
milrinone administration.
Phenylephrine was required in 11 of 22 patients receiving
amrinone and in 11 of 22 patients receiving
milrinone to maintain arterial blood pressure. The proportion of patients requiring an intravascular volume infusion (15 of 22 vs 17 of 22, P = NS) and the total fluid volume infused were similar (402 +/- 57 vs 350 +/- 49 mL, P = NS for
amrinone and
milrinone, respectively).
Amrinone and
milrinone seem to have similar hemodynamic effects after CPB, with the exception of blood pressure, although the need for vasopressor support of blood pressure did not differ. Selection between these two drugs may include nonhemodynamic considerations such as cost.
IMPLICATIONS:
Amrinone and
milrinone are drugs that improve cardiac contraction. Their effects have never been directly compared in patients. We found that
amrinone and
milrinone produced similar hemodynamic effects in adult patients undergoing cardiac surgery. Choice between the two drugs can be based on nonhemodynamic considerations such as cost.