Amrinone in cardiac surgical patients with left-ventricular dysfunction. A prospective, randomized placebo-controlled trial.
OBJECTIVE
To evaluate the efficacy of amrinone for facilitating weaning from cardiopulmonary bypass (CPB).


METHODS
Prospective, randomized, double-blind, placebo-controlled trial with epinephrine as "rescue" therapy.


METHODS
Operating room of a large, metropolitan tertiary-care center.


METHODS
Thirty-nine patients with preoperative left ventricular dysfunction undergoing cardiac surgery. Thirty-three patients underwent aortocoronary bypass grafting; six patients underwent valve replacement for severe mitral or aortic regurgitation.


METHODS
Patients received either amrinone (1.5 mg/kg loading dose plus 10 micrograms/kg/min maintenance infusion; n = 20) or placebo (n = 19) in a randomized double-blind fashion shortly (median, 10.5 min; range, 2 to 24 min) before separation from CPB. Inotropic drugs (other than the study drug) were withheld prior to separation from CPB unless safety considerations demanded that the protocol be broken. Patients who could not be weaned from CPB, as well as those with a cardiac index of 2.2 L/min/m2 or less after weaning from CPB, received epinephrine (60 to 120 ng/kg/min) by infusion.


RESULTS
Fourteen of 19 patients receiving placebo but only 1 of the 20 patients receiving amrinone (p = 0.00001) required epinephrine infusion to separate from bypass. The cardiac index of 4 patients receiving placebo (but no patients with amrinone) failed to exceed 2.2 L/min/m2 despite epinephrine infusion, requiring the protocol to be broken (p < 0.08). Blood concentrations of amrinone determined (only in the amrinone group) after separation from CPB confirmed that the dosage of amrinone produced an effective blood concentration. Fourteen of 19 patients receiving placebo and 17 of 20 patients receiving amrinone required an infusion of phenylephrine titrated to maintain systolic blood pressure less than 90 mm Hg. Seven patients (four with amrinone and three with placebo) required antiarrhythmic drug therapy. The outcome at 3 months was similar in the 2 groups.


CONCLUSIONS
Amrinone by itself is an effective agent to facilitate weaning from CPB, and therapy with amrinone reduced the need for individualized titration of epinephrine. Amrinone is as effective as individualized titration of epinephrine (after CPB) to improve cardiac function. Patients in the group receiving amrinone had no greater need for vasoconstricting agents than did patients in the group receiving placebo; however, proactive administration of amrinone before separation from CPB appears to offer no greater benefit to high-risk patients than selective administration of drugs (epinephrine) only to those patients who demonstrate the need for drug support at the time of weaning.
Butterworth
J F
JF
Department of Anesthesia, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, NC 27157.
Royster
R L
RL
Prielipp
R C
RC
Lawless
S T
ST
Wallenhaupt
S L
SL
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000676:Amrinone / Q000493:pharmacokinetics / Q000627:therapeutic use*; D002303:Cardiac Output, Low / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass / Q000009:adverse effects; D004311:Double-Blind Method; D004837:Epinephrine / Q000627:therapeutic use; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000187:drug effects; D011446:Prospective Studies; D016277:Ventricular Function, Left / Q000187:drug effects
D000676:Amrinone; D004837:Epinephrine