CARDIOPULMONARY PERFORMANCE DURING EXERCISE IN ACROMEGALY, AND THE EFFECTS OF ACUTE SUPPRESSION OF GROWTH-HORMONE HYPERSECRETION WITH OCTREOTIDE

We studied 10 adult patients with active acromegaly (4 men and 6 women , mean age 55 +/- 5 years and mean body mass index 27.9 +/- 1.1 kg/m(2 )) Control values for the echocardiographic and exercise studies were obtained from 10 normal subjects matched for sex and age (5 men and 5 women, age 51.1 +/- 3.7 years and body mass index 25.3 +/- 1 kg/m(2)). Each patient underwent: (1) blood sampling for growth hormone (GH) as say every 3 hours; (2) a 2-dimensional, guided M-mode echocardiographi c study; and (3) a cycloergometric exercise test at baseline and after treatment with a portable pump infusing octreotide, 500 mu g/24 hours subcutaneously. All patients had left ventricular hypertrophy. Systol ic function indexes did not significantly differ among normal subjects , whereas baseline Doppler studies showed abnormalities in left ventri cular diastolic filling in acromegalic patients. At anaerobic threshol d and at maximal exercise, acromegalic subjects sustained a significan tly (p < 0.05) decreased workload (54 +/- 23 vs 94 +/- 11 and 87 +/- 3 7 vs 152 +/- 15 W) compared with control subjects. After octreotide, b aseline heart rate (79 +/- 7 vs 87 +/- 8 beats/min, p < 0.05) and seru m GH levels significantly decreased compared with levels before admini stration of octreotide, Systolic and diastolic functional indexes at r est significantly improved after octreotide in acromegalic patients. B oth at anaerobic threshold and at maximal exercise, workload and oxyge n consumption were significantly increased after octreotide administra tion. Exercise capacity at anaerobic threshold was not significantly d ifferent in acromegalic subjects after octreotide infusion when compar ed with normal subjects. We hypothesize that elevated circulating GH l evels in acromegaly may have a functional negative effect on cardiovas cular function at baseline and during exercise. This functional altera tion is promptly reversible if GH levels are sustainedly decreased for 24 hours by continuous octreotide infusion.