A case and review of acromegaly-induced cardiomyopathy and the relationship between growth hormone and heart failure: cause or cure or neither or both?

Cardiac resynchronization therapy improves heart failure in one patient with acromegaly-induced cardiomyopathy: a case report

Background

Congestive heart failure is rarely observed in patients with acromegaly. Excessive growth hormone secretion and elevation of insulin-like growth factor 1 contribute to pathological changes in myocyte growth and structure, cardiac contractility, vascular function, and in later stage may progress to cardiac dysfunction. Early recognition of the condition is paramount, though the insidious progression of the disease commonly results in late diagnosis. Current standard regimens of pharmacological therapy, surgical treatment, radiotherapy are designed to normalize serum levels of both insulin-like growth factor 1 and growth hormone. In patients with late-stage heart failure due to acromegalic cardiomyopathy, cardiac resynchronization therapy might be a desirable treatment to help cardiac synchronization, improve symptoms, and eventually reduce hospital admissions together with mortality rates.

Case presentation

We describe a case of a 49-year-old man with a history of acromegaly who presented to our hospital with a diagnosis of decompensated systolic heart failure. Serial electrocardiograms showed wide (160–200 ms) QRS duration with left bundle branch block. Echocardiography showed severe left ventricular dysfunction that simultaneously achieved a left ventricular ejection fraction of 16%. Surgical indication was rarely assessed by neurosurgeons. Given that the stereotactic radiosurgery together with pharmacotherapy produced infinitesimal effects, cardiac resynchronization therapy was performed. Owing to biventricular synchronization and holding back reverse remodeling, the patient’s symptoms were successfully alleviated, and he was discharged from the hospital.

Conclusions

Congestive heart failure is a rare complication in acromegaly-induced cardiomyopathy (occurs in only 3% of patients). Early diagnosis and treatment with curative drugs more than cardiovascular implantable electronic devices might lead to better surgical outcomes in this group of patients.

Acromegalic cardiomyopathy: Epidemiology, diagnosis, and management

Acromegalic cardiomyopathy is the leading cause of morbidity and all-cause mortality in patients with acromegaly. Though acromegaly is a rare condition, the associated derangements are vast and severe. Stemming from an increase in circulating growth hormone (GH) and insulin-like growth factor-1 levels (IGF-1), acromegalic cardiomyopathy results in pathological changes in myocyte growth and structure, cardiac contractility, and vascular function. These molecular changes manifest commonly as biventricular hypertrophy, diastolic and systolic dysfunction, and valvular regurgitation. Early recognition of the condition is paramount, though the insidious progression of the disease commonly results in a late diagnosis. Biochemical testing, based on IGF-1 measurements, is the gold standard of diagnosis. Management should be centered on normalizing serum levels of both IGF-1 and GH. Transsphenoidal resection remains the most cost-effective and permanent treatment for acromegaly, though medical therapy possesses benefit for those who are not surgical candidates. Ultimately, achieving control of hormone levels results in a severe reduction in mortality rate, underscoring the importance of early recognition and treatment.

Elevated systolic blood pressure in male GH transgenic mice is age dependent

Acromegaly is associated with an increased incidence of cardiovascular disease. Transgenic mice expressing bovine GH (bGH) gene have previously been used to examine the effects of chronic GH stimulation on cardiovascular function. Results concerning systolic blood pressure (SBP) in bGH mice are conflicting. We hypothesized that these discrepancies may be the result of the various ages of the mice used in previous studies. In the current study, SBP was assessed monthly in male bGH mice from 3-12 months of age. Factors known to alter blood pressure were assessed during this time and included: levels of brain natriuretic peptide (BNP) and glucose homeostasis markers, and renal levels of angiotensin-converting enzyme 2 and endothelial nitric oxide synthase. Beginning at 6 months of age bGH had increased SBP compared with wild-type controls, which remained elevated through 12 months of age. Despite having increased blood pressure and cardiac BNP mRNA, bGH mice had decreased circulating levels of BNP. Additionally, bGH mice had an age-dependent decline in insulin levels. For example, they were hyperinsulinemic at 3 months, but by 11 months of age were hypoinsulinemic relative to wild-type controls. This decrease in insulin was accompanied by improved glucose tolerance at 11 months. Finally, both angiotensin-converting enzyme 2 and endothelial nitric oxide synthase expression were severely depressed in kidneys of 11-month-old bGH mice. These results indicate that elevated SBP in bGH mice is dependent on age, independent of insulin resistance, and related to alterations in both the natriuretic peptide and renin-angiotensin systems.

Ghrelin and cardiovascular diseases

Ghrelin, a newly discovered bioactive peptide, is a natural endogenous ligand of the growth hormone (GH) secretagogue receptor and initially identified as a strong stimulant for the release of GH. Subsequent research has shown that ghrelin and its various receptors are ubiquitous in many other organs and tissues. Moreover, they participate in the regulation of appetite, energy, bodyweight, metabolism of glucose and fat, as well as modulation of gastrointestinal, cardiovascular, pulmonary, immune functions and cell proliferation/apoptosis. Increasing evidence has demonstrated that ghrelin has a close relationship with cardiovascular system. Ghrelin and its receptors are widely distributed in cardiovascular tissues, and there is no doubt that the effects of ghrelin in the cardiovascular system are mediated not only via its growth-hormone-releasing effect but also by its direct effects on the heart. Exogenous administration of ghrelin can dilate peripheral blood vessels, constrict coronary artery, improve endothelial function, as well as inhibit myocardial cell apoptosis. So, ghrelin may have cardiovascular protective effect, including lowering of blood pressure, regulation of atherosclerosis, and protection from ischemia/reperfusion injury as well as improving the prognosis of myocardial infarction and heart failure. Some of these new functions of ghrelin may provide new potential therapeutic opportunities for ghrelin in cardiovascular medicine. In this paper, we will review the existing evidence for cardiovascular effects of ghrelin, including the cardiovascular function, the variations in ghrelin plasma levels in pathophysiologicalogical conditions, the possible protective mechanisms of ghrelin, as well as its future potential therapeutic roles.