The hemodynamic and neurohonnonal effects of low doses of tezosentan (an endothelih A/B receptor antagonist) in patients with acute heart failure

Background: In, previous studies (the RITZ project), tezosentan, an intravenous (i.v.)-balanced dual endothelin (ET-A/B) antagonist, in doses of 50 and 100 mg/h improved the hemodynamics but not the clinical outcome of patients with acute heart failure (AHF). Objective: To evaluate the effect of lower doses of tezosentan in patients with AHF. Subjects and methods: Included were 130 patients hospitalized due to AHF with dyspnea at rest, despite initial treatment, and were in need of hemodynamic monitoring with cardiac index (CI) < 2.5 1/min/m(2) and wedge pressure greater than or equal to 20 mm Hg. Patients were randomized in a double-blind fashion to receive placebo or tezosentan: 0.2, 1, 5, or 25 mg/h for 24 It. Results: The primary endpoint of the study, CI increase at 6 It of treatment, was significant in the 5 and 25 mg/h groups. Tezosentan induced a dose-dependent increase in CI and a decrease in wedge pressure, peaking after 3 h in the 5 and 25 mg/h groups. In the 1-mg/ h group, this effect was smaller during the first 6 h and increased gradually, becoming significant at 24 h and beyond treatment discontinuation. There was no hemodynamic effect in the 0.2 mg/h arm. Type-B natriuretic,peptide (BNP) decreased in the 1, 5, and 25 mg/h groups but not on placebo. Endothelin levels were significantly increased by the 5 and 25 mg/h groups but not in the lower (less than or equal to 1 mg/h) tezosentan doses. Urine output decreased on the 25-mg/h dose. There was a trend towards improvement in patients' subjective dyspnea score and worsening heart failure events, mainly in the 1 mg/h group. Conclusions: In patients admitted with AHF, tezosentan doses of 1-25 mg/h are efficacious in improving the hemodynamics and reducing BNP. Tezosentan doses beyond 1 mg/h increased plasma endothelin levels and reduced urine output, probably limiting their clinical efficacy, as compared to tezosentan 1 mg/h. (C) 2004 European Society of Cardiology. Published by Elsevier B.V.