Dose-related beneficial long-term hemodynamic and clinical efficacy of irbesartan in heart failure

OBJECTIVES The primary purpose of this study was to determine the acute and long-term hemodynamic and clinical effects of irbesartan in patients with heart failure. BACKGROUND Inhibition of angiotensin II production by angiotensin-converting enzyme (ACE) inhibitors reduces morbidity and mortality in patients with heart failure. Irbesartan is an orally active antagonist of the angiotensin II AT1 receptor subtype with potential efficacy in heart failure. METHODS Two hundred eighteen patients with symptomatic heart failure (New York Heart Association [NYHA] class II–IV) and left ventricular ejection fraction ≤40% participated in the study. Serial hemodynamic measurements were made over 24 h following randomization to irbesartan 12.5 mg, 37.5 mg, 75 mg, 150 mg or placebo. After the first dose of study medication, patients receiving placebo were reallocated to one of the four irbesartan doses, treatment was continued for 12 weeks and hemodynamic measurements were repeated. RESULTS Irbesartan induced significant dose-related decreases in pulmonary capillary wedge pressure (average change −5.9 ± 0.9 mm Hg and −5.3 ± 0.9 mm Hg for irbesartan 75 mg and 150 mg, respectively) after 12 weeks of therapy without causing reflex tachycardi and without increasing plasm norepinephrine. The neurohormonal effects of irbesartan were highly variable and none of the changes was statistically significant. There was significant dose-related decrease in the percentage of patients discontinuing study medication because of worsening heart failure. Irbesartan was well tolerated without evidence of dose-related cough or azotemia. CONCLUSIONS Irbesartan, at once-daily doses of 75 mg and 150 mg, induced sustained hemodynamic improvement and prevented worsening heart failure.