A double-blind, cross-over comparison of the effects of a loop diuretic and a dopamine receptor agonist as first line therapy in patients with mild congestive heart failure.

We compared the effects of the orally active dopamine agonist ibopamine with the loop diuretic frusemide as first-line therapy in patients with mild congestive heart failure. Fourteen patients with New York Heart Association class II congestive heart failure were enrolled in a double-blind, cross-over study. After baseline measurements of clinical and symptomatic status, modified Bruce exercise time, high-level exercise time, corridor walk time, regional blood flow, pedometer scores, 24 h urine volume and sodium excretion and neurohumoural factors, patients were randomly allocated to receive either frusemide 40 mg o.d. or ibopamine 100 mg t.d.s. for 8 weeks. Assessments were performed at 2 weekly intervals. After 8 weeks, patients crossed over into the alternate treatment arm for a further 8 weeks, with further assessments performed every 2 weeks. There were four exacerbations of heart failure during ibopamine treatment and none during frusemide treatment. After 8 weeks of treatment, modified Bruce exercise time was 901 +/- 73 s with frusemide and 646 +/- 134 s with ibopamine (P < 0.05). Twenty-four hour urinary sodium excretion at weeks 2 and 4 (P < 0.05), and 24 h urinary volume at week 2 (P = 0.0001) were lower during ibopamine treatment. At week 8, supine (P = 0.076) and erect renin (P = 0.05) were lower with ibopamine treatment. In conclusion, ibopamine is ineffective as first line therapy for congestive heart failure, probably because of a lesser diuretic potency than frusemide.