The predictive value of GH and IGF-1 burdens for ischaemic heart disease and cardiomyopathy in patients with treated acromegaly.
H Clarke, CN Jayasena, A Comninos, M Donaldson, K Meeran, WS Dhillo
Imperial Centre for Endocrinology
BACKGROUND: Patients with acromegaly require lifetime monitoring due to the excess mortality and morbidity associated with untreated disease, and the propensity for disease relapse following treatment. There is controversy whether growth hormone (GH) or insulin-like growth factor-1 (IGF-1), better predicts the onset of cardiovascular complications such as cardiomyopathy and ischaemic heart disease (IHD) in acromegalic patients.
AIM: To examine associations of overall GH and IGF-1 exposure with IHD and cardiomyopathy, in patients with treated acromegaly.
METHODS: Records of 116 patients with treated acromegaly attending a single Endocrine centre were examined retrospectively. GH and IGF-1 burdens were calculated by multiplying the overall mean basal GH and mean IGF-1 index during patient follow-up, by the number of years since diagnosis of acromegaly. IGF-1 index was defined as serum IGF-1 divided by the upper limit of reference range. Mean GH and IGF-1 burdens were compared between patients with and without cardiomyopathy and IHD.
RESULTS: IHD was present in 11.2% of treated acromegalic patients. GH burden was significantly higher in patients with IHD when compared with patients without IHD (mean GH burden in years.mcg/L: 94.6 ± 32.8, IHD; 56.7 ± 7.4, no IHD; p = 0.009). Mean IGF-1 burden was not significantly different between patients with and without IHD. Evidence of cardiomyopathy was recorded in 20% of treated acromegalic patients. Mean IGF-1 burden was significantly higher in patients with cardiomyopathy when compared with patients without cardiomyopathy (mean IGF-1 burden in years: 23.5 ± 4.4, cardiomyopathy; 16.2 ± 1.6, no cardiomyopathy; p = 0.011). Mean GH burden was not significantly different between patients with and without cardiomyopathy.
CONCLUSION: These results suggest that both GH burden and IGF-1 burden are useful markers of cardiovascular morbidity in treated acromegalic patients. This study highlights the importance of monitoring both serum GH and IGF-1 in treated acromegalic patients.