Cardiovascular Function in Acromegaly

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Abstract
Even with modern treatment, acromegaly is associated with a 2- to 3-fold increase in mortality, mainly from vascular dis- ease, which is probably a result of the long exposure of tissues to excess GH before diagnosis and treatment. There is accu- mulating evidence that effective treatment to lower serum GH levels to less than 1-2 ng/ml (glucose suppressed or random, respectively) and normalize IGF-I improves long-term out- come and survival. In addition to recognized cardiovascular risk factors of hypertension, type 2 diabetes mellitus, and dyslipidemia, there is accumulating evidence of specific structural and functional changes in the heart in acromegaly. Along with endothelial dysfunction, these changes may con- tribute to the increased mortality in this disease. There are specific structural changes in the myocardium with increased myocyte size and interstitial fibrosis of both ventricles. Left ventricular hypertrophy is common even in young patients with short duration of disease. Some of these structural changes can be reversed by effective treatment. Functionally, the main consequence of these changes is impaired left ven- tricular diastolic function, particularly when exercising, such that exercise tolerance is reduced. Diastolic function im- proves with treatment, but the effect on exercise tolerance is more variable, and more longitudinal data are required to assess the benefits. What scant data there are on rhythm changes suggest an increase in complex ventricular arrhyth- mias, possibly as a result of the disordered left ventricular architecture. The functional consequences of these changes are unclear, but they may provide a useful early marker for the ventricular remodeling that occurs in the acromegalic heart. Endothelial dysfunction, especially flow-mediated di- latation, is an early marker of atherosclerosis, and limited data imply that this is impaired in active acromegaly and can be improved with treatment. Similarly, early arterial struc- tural changes, such as thickened intima media layer, appear more common in acromegalics, and there are hints that this may diminish with effective treatment, although more studies are required for a definite conclusion on this topic. In con- clusion, impaired cardiac and endothelial structure and func- tion in acromegaly are risk factors for vascular mortality and should be regarded as legitimate therapeutic targets in the overall management of this condition. (Endocrine Reviews 24: 272-277, 2003)

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