Cardiac effects of growth hormone in physiology and in heart failure

Two-dimensional speckle tracking echocardiography demonstrates no effect of active acromegaly on left ventricular strain

BACKGROUND

Speckle tracking echocardiography (STE) allows for the study of myocardial strain (ε), a marker of early and subclinical ventricular systolic dysfunction. Cardiac disease may be present in patients with acromegaly; however, STE has never been used to evaluate these patients.

OBJECTIVE

To evaluate left ventricular (LV) global longitudinal strain in patients with active acromegaly with normal LV systolic function.

DESIGN

Cross-sectional clinical study.

METHODS

Patients with active acromegaly with no detectable heart disease and a control group were matched for age, gender, arterial hypertension and diabetes mellitus underwent STE. Global LV longitudinal ε (GLS), left ventricular mass index (LVMi), left ventricular ejection fraction (LVEF) and relative wall thickness (RWT) were obtained via two-dimensional (2D) echocardiography using STE.

RESULTS

Thirty-seven patients with active acromegaly (mean age 45.6 ± 13.8; 48.6% were males) and 48 controls were included. The mean GLS was not significantly different between the acromegaly group and the control group (in %, -20.1 ± 3.1 vs. -19.4 ± 2.2, p = 0.256). Mean LVMi was increased in the acromegaly group (in g/m², 101.6 ± 27.1 vs. 73.2 ± 18.6, p < 0.01). There was a negative correlation between LVMi and GLS (r = -0.39, p = 0.01).

CONCLUSIONS

Acromegaly patients, despite presenting with a higher LVMi when analyzed by 2D echocardiography, did not present with impairment in the strain when compared to a control group; this finding indicates a low chance of evolution to systolic dysfunction and agrees with recent studies that show a lower frequency of cardiac disease in these patients.

Congenital hypopituitarism presenting as dilated cardiomyopathy in a child

Congenital hypopituitarism is commonly diagnosed either in infancy with neonatal hypoglycemia, prolonged jaundice and/or microphallus or in early to mid-childhood because of short stature. Replacement of deficient hormones allows the affected children to have a normal and productive life. We describe a 10-year-old boy with congenital hypopituitarism whose parents first sought definitive medical attention when the child developed congestive heart failure due to dilated cardiomyopathy, presumably secondary to prolonged untreated central hypothyroidism and growth hormone deficiency.

Evidence for distinct effects of GH and IGF-I in the metabolic syndrome

AIMS

The metabolic syndrome is a cluster of cardiovascular risk factors which include central obesity, dyslipidaemia, glucose intolerance and hypertension. These risk factors are common in patients with growth hormone (GH) deficiency, suggesting a role for the somatotropic axis in the development of metabolic syndrome.

METHODS

We used factor analysis to investigate the relationships linking serum levels of GH and insulin-like growth factor I (IGF-I) to metabolic syndrome variables (high-density lipoprotein cholesterol, triglycerides, fasting glucose, blood pressure and waist circumference). We studied 359 men and 388 women from the Data from an Epidemiological Study on the Insulin Resistance syndrome (DESIR). Their age range was 30-64 years.

RESULTS

Three independent latent factors explained 61% of the total variance in women and four factors explained 73% in men. In both men and women, IGF-I showed a strong positive correlation with the lipid factor and a negative correlation with the obesity/glucose factor. In women, GH showed a strong negative correlation with the obesity/glucose factor but not the lipid factor. In men, GH was unrelated to the lipid and obesity/glucose factors. The blood pressure factor was not related to GH or IGF-I. In contrast with IGF-I, GH was significantly lower in women with metabolic syndrome (1575 +/- 449 pg/ml) than in the other women (2121 +/- 520 pg/ml, P = 0.002). No significant difference was observed in men for GH or IGF-I.

CONCLUSION

Our results support a link between the somatotropic axis and several features of the metabolic syndrome, and suggest distinct effects of GH and IGF-I on these parameters.