Amrinone in the treatment of chronic cardiac failure

The efficacy and safety of oral amrinone were examined in 17 patients with moderately severe to severe heart failure that was refractory to standard medical therapy and vasodilators. The short-term and 28 week response to open amrinone therapy was assessed first, followed by a placebo-controlled, double-blind withdrawal study of two 13 week stages in nine patients. Rest and exercise ventricular function were determined before and after 32 hours of amrinone; aerobic capacity was serially assessed. After 2 hours, 1.64 mg/kg amrinone produced a 40% (p less than 0.001) increase in cardiac output and a 32% (p less than 0.02) decrease in pulmonary wedge pressure without altering heart rate or blood pressure. The exercise cardiac index-wedge pressure curve obtained 32 hours after the first oral dose was significantly shifted (p less than 0.05) above control values. A sustained improvement in maximal oxygen uptake was noted during long-term open amrinone therapy. Subsequently, seven of the patients randomized to placebo therapy had a significant deterioration of symptoms or exercise tolerance, or both. After 4 weeks of readministration of amrinone, clinical stability was once again established and exercise tolerance was improved by Weeks 8 to 16. Adverse effects of thrombocytopenia (one patient) and hepatic dysfunction (one patient) attributable to amrinone were observed. It is concluded that amrinone is effective in the long-term treatment of chronic cardiac failure.