Forty patients (30 men, 10 women) with severe congestive heart failure NYHA III (n = 30) and IV (n = 10) due to coronary heart disease (n = 19) or dilative cardiomyopathy (n = 21) were enrolled in this study. Mean age was 57 years. Eight patients each received 0.25 mg/kg, 0.5 mg/kg, 1.0 mg/kg or 2.0 mg/kg piroximone intravenously or placebo (saline). Measurements were performed before and up to 4 h after drug administration using a Swan-Ganz right-heart thermodilution catheter.
Results: All changes stated were significant (p < 0.05). Pulmonary capillary wedge pressure was lowered by max. 27% (0.25 mg/kg) to 52% (2.0 mg/kg) 30 min after drug injection. Significant effects were seen for 60 (0.25 mg/kg) to 120 min (2.0 mg/kg). Mean pulmonary artery pressure decreased by max. 8% to 24% after 30 min. Effects lasted for 30 to 60 min. Cardiac index increased by max. 26% to 52% after 30 min. Significant changes occurred up to 4 h after 2.0 mg/kg. Systemic vascular resistance fell by max. 16% to 34%. Effect duration was 1 h (0.5 mg/kg up to 4 h) (2.0 mg/kg). Minor changes of arterial blood pressure (minus 7% after 0.5 mg/kg) and heart rate (minus 14% after 2.0 mg/kg) were seen.
Conclusion: Small doses of piroximone i.v. increase cardiac output by about 20% while preload and afterload decrease by about 20%. For most cases no doses higher than 0.5 mg/kg will be needed for the treatment of severe congestive heart failure.