Objective: To determine the cardiovascular effects of the somatostatin analog octreotide in patients with acromegaly.

Design: Prospective nonrandomized study.

Setting: Referral-based endocrinology clinic.

Patients: Seven patients with active acromegaly, three of whom had refractory congestive heart failure. The other four patients were free of symptoms associated with heart failure.

Interventions: All patients were treated with octreotide, 100 to 500 μg subcutaneously three times daily. The three patients with heart failure continued to receive cardiovascular therapy (angio-tensin converting enzyme inhibitors, digitalis, diuretics).

Measurements and Main Results: During octreotide therapy, patients showed a rapid decrease in growth hormone and insulin-like growth factor 1 (IGF-1): Mean levels (± SD) fell from 28.1 ± 32.7 μg/L to 5.2 ± 8.3 μg/L and 740 ± 126 μg/L to 372 ± 64 ±g/L, respectively (P < 0.025). Plasma volume returned to normal and heart rate decreased significantly. In the four patients without heart failure, right-heart catheterization done before and after 3 months of octreotide therapy showed an 18.3% ± 11% reduction in stroke volume and a return to normal of the cardiac index. The three patients with congestive heart failure, evaluated before and after 40 days and up to 2 years of therapy, showed a dramatic clinical improvement that was associated with an increase in stroke volume (by 24% to 51%). In these patients, the cardiac index remained in the normal range, filling pressures were markedly decreased, and pulmonary wedge pressure returned to normal. This improvement was sustained for up to 3 years in the two patients with heart failure who were receiving long-term treatment.

Conclusion: The rapid and sustained cardiac improvement seen in our patients shows that octreotide therapy for patients with acromegaly may be highly beneficial, even in those patients with advanced cardiac failure.