Increased arterial intima-media thickness by B-M mode echodoppler ultrasonography in acromegaly

Can signal peptide-CUB-EGF domain-containing protein 1 (SCUBE-1) be used as an indicator of endothelial dysfunction in acromegaly patients?

PURPOSE

Acromegaly is closely related to increased oxidative stress and endothelial dysfunction (ED). This study aimed to evaluate, for the first time in the literature, signal peptide-CUB-EGF domain-containing protein 1 (SCUBE-1) and endothelial nitric oxide synthase e(NOS) levels in the setting of acromegaly.

METHOD

A total of 56 acromegaly patients and a control group composed of 30 healthy volunteers were included in this study. In the postoperative follow-up, patients were grouped as active or in-remission according to their GH and IGF-1 levels in oral glucose stimulation test (OGST). After detailed physical examination of acromegaly patients and the control subjects, 8-hour fasting blood samples were collected to evaluate biochemical parameters including lipid profile, anterior pituitary hormones, and SCUBE-1 and e(NOS) levels.

RESULTS

Inactive and active acromegaly was noted in 78.6% and 21.4% of patients, respectively. The median (min-max) SCUBE-1 levels were significantly higher in the inactive acromegaly and active acromegaly groups than in the control group (1.6(0.4-2.4) and 1.8(1.1-2.5) vs. 0.4(0.2-1.0) ng/mL, respectively, p < 0.001 for each). The median (min-max) e(NOS) levels were significantly higher in the inactive acromegaly and active acromegaly groups than in the control group (132.7 (26.8-602.9) and 137.3 (69.7-488.7) vs. 83.9 (16.4-218.7) pg/mL, p = 0.018 and p = 0.048, respectively). We have also detected positive correlations of e(NOS) with leukocyte (r = 0.307, p = 0.021) and neutrophil counts (r = 0.309, p = 0.021).

CONCLUSION

Our study revealed for the first time in literature that SCUBE-1 levels, being a novel marker for ED, were significantly higher in acromegaly patients than in control subjects. When supported with clinical studies, SCUBE-1can be used as an early indicator of endothelial damage in acromegaly patients.

Capillary microarchitectural changes are independent of disease activity in acromegaly

OBJECTIVE

Although atherosclerosis-related macrovascular complications are well known in acromegaly, studies on endothelial function and arteriolar level are contradictory. In order to test the hypothesis, microvascular changes associated with macrovascular changes in acromegaly, we aimed to evaluate microvascular changes in nailfold capillaries and carotid intima-media thickness (CIMT) in patients with acromegaly.

DESIGN

In this cross-sectional observation study, of total 70 patients with acromegaly [ten (14.3 %) were active acromegaly (AA), 60 (85.7 %) were controlled acromegaly (CA)] and 74 healthy controls were enrolled. Microvascular structure was evaluated using the nailfold video capillaroscopy, and CIMT was measured using ultrasonography.

RESULTS

The median number of capillaries was less [10 no./mm (min-max: 5-16) vs. 11 no./mm (min-max: 9-15); p = 0.001] in the acromegaly group than in the controls. Capillaries below 6-8 per/mm was more common in the acromegaly patients [six (8.6 %) vs. one (1.4 %); p = 0.046]. All capillaroscopic parameters were similar among the patients with CA or AA. CIMT levels were higher in the acromegaly group than in the control group [0.60 mm (0.43-0.86) vs. 0.38 mm (0.27-0.59); p < 0.001], and AA patients had higher CIMT than CA patients (p = 0.037). None of the clinical or laboratory parameters including growth hormone and IGF-1 were related to capillaroscopic parameters or CIMT.

CONCLUSION

Decreased capillary number was the major capillaroscopic finding in acromegaly and there was no significant difference between active and controlled cases, but CIMT was found to be higher in the active group. Increased CIMT levels in acromegaly were not associated with capillary changes. Large-scale, prospective studies are needed to make a definite conclusion about the effect of the disease activity on nailfold capillaries and its association with macrovascular changes.

Genetic Etiology of Ichthyosis in Turkish Patients: Nextgeneration Sequencing Identified Seven Novel Mutations

Objective:

Acromegaly is a rare disease associated with increased mortality. Reports on coronary artery disease in acromegaly are controversial. This study aimed to investigate the possible association of epicardial adipose tissue thickness with cardiovascular risk in patients with acromegaly.

Methods:

The study included 38 patients followed up with the diagnosis of acromegaly and 29 healthy controls. Patients with acromegaly were divided into controlled and uncontrolled acromegaly groups based on insulin-like growth factor-1 levels. Epicardial adipose tissue thickness measurements were obtained from chest computed tomography, and laboratory data were extracted from patient files.

Results:

Twenty-nine patients (76.3%) had controlled acromegaly. Eleven patients with acromegaly had diabetes mellitus (28.9%), 18 (47.4%) had hypertension, and 27 (71%) had a concomitant chronic disease. Epicardial adipose tissue thickness was significantly increased in the acromegaly group (p<0.001). No significant difference was observed between the controlled and uncontrolled acromegaly groups in terms of the epicardial adipose tissue thickness. Age was the only parameter that was significantly correlated with the epicardial adipose tissue thickness. When the Framingham risk score was calculated, the 10-year cardiovascular risk of patients with acromegaly was 5.63%.

Conclusions:

The epicardial adipose tissue thickness is increased in acromegaly. However, this increase may not have clinical relevance in terms of cardiovascular risk.

"Subclinical atherosclerosis in acromegaly: Possible association with cardiovascular risk factors rather than disease activity"

OBJECTIVE

Cardiovascular (CV) disease is still a major cause of excessive morbidity and mortality in patients with active acromegaly, which may be attributed to a high prevalence of associated pro-atherosclerotic risk factors. However, a direct effect of GH/IGF-1 excess on the vasculature has been previously suggested, warranting further investigation. The present study was designed to investigate whether chronic GH/IGF-1 excess is associated with an increased prevalence of subclinical atherosclerosis in patients with acromegaly.

DESIGN

We measured carotid intima-media thickness (cIMT) and assessed carotid plaques by ultrasonography along with classical CV risk factors in 54 acromegaly patients (34 females, 50 ± 12 years and compared those with 62 (42 females, 53 ± 13 years) age-, sex- and CV risk factors- matched controls. In order to compare cIMT measurements between patients and controls we analyzed common carotid artery far wall data as well as a combined measurement result, which consisted of the mean value of the six different measurements, three at each side.

RESULTS

mean ± SD serum GH and IGF-1 levels were 2.76 ± 4.65 ng/mL and 1.7 ± 1.25 x ULN, respectively, in all acromegaly patients. Age, body mass index, blood pressure, lipid levels, fasting glucose and Framingham's global cardiovascular risk score classification were similar comparing patients and controls. Combined median [IQR] cIMT measurements were similar in acromegaly patients and matched controls (0.59 [0.52-0.66] mm vs. 0.59 [0.52-0.69] mm; P = 0.872) as well as in acromegaly patients with active and controlled disease (0.59 [0.51-0.68] mm vs. 0.60 [0.54-0.68] mm; P = 0.385). No significant correlations were observed between cIMT measurements and GH (Spearman r = 0.1, P = 0.49) or IGF-1 (Spearman r = 0.13, P = 0.37) levels in patients with acromegaly. Carotid atherosclerotic plaques prevalence was similar in patients and controls (26% vs. 32%; P = 0.54) as well as in patients with active and controlled acromegaly (22% vs. 30%; P = 0.537).

CONCLUSIONS

Our data suggest that GH/IGF-1 excess itself is not one of the main drivers of subclinical morphological atherosclerosis changes in patients with acromegaly and that optimal control of acromegaly-associated CV risk factors may preserve vasculature structure even when strict biochemical control is not achieved.

Effects of Long-Acting Somatostatin Analogues on Lipid Metabolism in Patients with Newly Diagnosed Acromegaly: A Retrospective Study of 120 Cases

The short-term effects of long-acting somatostatin analogues (SSAs) on lipid profiles in patients with acromegaly are not well studied. We retrospectively analyzed the effects of SSAs on lipid profiles and associated cardiovascular risk factors in a cohort of 120 newly diagnosed acromegaly patients. In this study, 69 females and 51 males were included. These patients were treated with either octreotide LAR (OCT) or lanreotide SR (LAN) for 3 months. After SSAs treatment, both GH and IGF-1 significantly decreased (p<0.001). Triglyceride (TG), total to high-density lipoprotein cholesterol (HDL-C) ratio, and lipoprotein (a) [Lp(a)] levels were significantly decreased, while HDL-C levels were increased (p<0.05). The reduction of mean serum GH (GH_m) was positively associated with the decrease of TG (r=0.305, p=0.001) and Lp(a) (r=0.257, p=0.005), as well as the increase of HDL-C (r=-0.355, p<0.001). The changes of lipid profiles were observed only in OCT group, but not in LAN group. In addition, systolic blood pressure (SBP) had significantly declined after SSAs treatment, with an average reduction of 4.4 mmHg (126.7±1.28 vs. 122.3±1.44 mmHg, p=0.003), while no change was observed regarding diastolic blood pressure (DBP) (p>0.05). Fasting insulin, fasting C-peptide, and HOMA-IR were significantly decreased after SSAs treatment. In conclusion, our current study revealed that short-term SSAs treatment improves lipid profiles and other cardiovascular risk factors in patients with acromegaly.

Endothelial dysfunction in patients with acromegaly and It's association with Endocan

OBJECTIVE

This study aims to assess endocan levels in patients with acromegaly who have active disease or disease in remission and to investigate a relation between endocan levels and endothelial dysfunction in these patients.

DESIGN

The study is a case-control study. Study was conducted at Istanbul Medeniyet University Goztepe Training and Research Hospital between 2013 and 2019. Patients who were older than 18 years with acromegaly diagnosis were recruited if they agreed to participate. Patients with uncontrolled diabetes (DM), hypertension (HT), hyperlipidemia, decompensated heart failure, immune or infectious diseases, moderate-severe valve disease and stage 3 or more advanced chronic kidney disease were excluded. There were 30 healthy control subjects who agreed to participate to the study. Patients with acromegaly were divided into two groups as: disease active patients and patients in remission. Serum endocan levels were measured with enzyme linked immunosorbent assay (ELISA) method endothelial function was assessed with flow mediated dilatation (FMD).

RESULTS

There were 85 patients included to the study. Twenty-three patients had active disease, 31 were in remission and 31 were healthy controls. FMD was higher in controls compared to patients in active disease and patients in remission (p < 0.001). There was no difference between patients with active disease for FMD and patients in remission (p = 0.088). There was statistically significant correlation between FMD and endocan and insulin like growth hormone-1 (IGF-1) levels of patients with acromegaly. As FMD increased endocan and IGF-1 decreased. A moderate negative relation between FMD and endocan was identified (p < 0.001, r:-0.409) as well as FMD and IGF-1 levels (p:0.011, r:-0.377). Along with endocan and IGF-1, DM, HT, sex, body mass index, age and uric acid were associated with changes in FMD.

CONCLUSIONS

Endocan levels and endothelial function measured with FMD have an inverse relationship. Endocan may prove to be a marker for endothelial dysfunction in acromegaly.

Acromegaly, inflammation and cardiovascular disease: a review

Acromegaly is characterized by Growth Hormone (GH) and Insulin-like Growth Factor 1 (IGF-1) excess. Uncontrolled acromegaly is associated with a strongly increased risk of cardiovascular disease (CVD), and numerous cardiovascular risk factors remain present after remission. GH and IGF-1 have numerous effects on the immune and cardiovascular system. Since endothelial damage and systemic inflammation are strongly linked to the development of CVD, and have been suggested to be present in both controlled as uncontrolled acromegaly, they may explain the presence of both micro- and macrovascular dysfunction in these patients. In addition, these changes seem to be only partially reversible after remission, as illustrated by the often reported presence of endothelial dysfunction and microvascular damage in controlled acromegaly. Previous studies suggest that insulin resistance, oxidative stress, and endothelial dysfunction are involved in the development of CVD in acromegaly. Not surprisingly, these processes are associated with systemic inflammation and respond to GH/IGF-1 normalizing treatment.

Cardiometabolic Risk in Acromegaly: A Review With a Focus on Pasireotide

Acromegaly is a disease due to chronic GH excess and a consequent rise in IGF-1 levels. This rare endocrine condition is associated with metabolic alterations such as hyperglycaemia, dyslipidaemia, and systemic arterial hypertension, which, in addition to GH excess-related cardiovascular changes, play critical roles in increasing cardiovascular risk and mortality rates. Biochemical control of acromegaly, achieved by means of surgical, and/or medical treatment, positively impacts on cardiovascular risk factors and metabolic alterations, reducing overall patient mortality. However, treatment modalities of acromegaly and disease control differently impact on glucose homeostasis and lipid changes, and consequently on cardiometabolic risk. In this regard, pasireotide was shown to significantly influence glucose metabolism. This review summarizes the cardiometabolic consequences of acromegaly and its treatment, focusing on available data around the effects of medical therapy with pasireotide on factors that influence cardiometabolic risk.

Changes in metabolic parameters and cardiovascular risk factors after therapeutic control of acromegaly vary with the treatment modality. Data from the Bicêtre cohort, and review of the literature

CONTEXT

Untreated acromegaly is associated with increased morbidity and mortality due to malignant, cardiovascular, and cerebrovascular disorders. Effective treatment of acromegaly reduces excess mortality, but its impact on cardiovascular risk factors and metabolic parameters are poorly documented.

AIM

We analyzed changes in cardiovascular risk factors and metabolic parameters in patients receiving various treatment modalities.

PATIENTS AND METHODS

We retrospectively studied 96 patients with acromegaly, both at diagnosis and after IGF-I normalization following surgery alone (n = 51) or medical therapy with first generation somatostatin analogues (SSA, n = 23), or pegvisomant (n = 22). Duration of follow-up was 77 (42-161) months, 75 (42-112) months, and 62 (31-93) months, in patients treated with surgery alone, SSA, and pegvisomant, respectively. In all the cases except four, patients treated medically had underwent previous unsuccessful surgery.

RESULTS

IGF-I normalization was associated with increased body weight, decreased systolic blood pressure (SBP) in hypertensive patients, decreased fasting plasma glucose (FPG) and HOMA-IR and HOMA-B levels, increased HDL cholesterol (HDLc); whereas, LDL cholesterol (LDLc) was not significantly different. Plasma PCSK9 levels were unchanged in patients with available values. Cardiovascular and metabolic changes varied with the treatment modality: surgery, but not pegvisomant, had a beneficial effect on SBP; FPG decreased after surgery but increased after SSA; the decline in HOMA-IR was only significant after surgery; pegvisomant significantly increased LDLc and total cholesterol; whereas SA increased HDLc and had no effect on LDLc levels.

CONCLUSION

Treatments used to normalize IGF-I levels in patients with acromegaly could have differential effects on cardiovascular risk factors and metabolic parameters.

The Endothelium in Acromegaly

Growth hormone (GH) and insulin like growth factor-1 (IGF-1) excess induce well-known deleterious effects on the cardiovascular system, especially after long-term exposition. Acromegaly, a condition of chronic GH and IGF-1 hypersecretion, is frequently associated to cardiovascular complications, although recent studies have shown a reduction in the prevalence of these comorbidities in well-controlled patients and a mortality risk similar to normal aging population. Many factors could contribute to the increased cardiovascular risk of acromegaly patients. Among these factors, the endothelium plays a key role in the pathogenesis of atherosclerotic plaques and could be considered an early marker of atherosclerosis and cardiovascular dysfunction. In this review we examined the relationship between GH/IGF-1 excess and the endothelium, from basic studies to clinical evidence. Many studies involving various arterial districts (microvascular arteries of retina, kidney and brain, and major vessels as carotid and aorta) showed that GH/IGF-1 excess promotes endothelial dysfunction via several different mechanisms. Increased endothelial proliferation, dysfunction of endothelial progenitor cells, increased oxidative stress, and compromised oxidative defenses are the main factors that are associated with endothelial dysfunction. In the general population, these alterations are associated with the development of atherosclerosis with an increased incidence of coronary artery disease and cerebrovascular complications. However, in acromegaly this is still a debated issue, despite the presence of many pro-atherogenic factors and comorbidities, such as hypertension, diabetes, sleep apnoea, and metabolic syndrome. Preclinical markers of atherosclerosis as arterial intima media thickness, pulse wave velocity and flow mediated dilation seem to be impaired in acromegaly and partly mediated by the endothelium dysfunction. In conclusion, the pathophysiology of endothelial dysfunction in the condition of GH and IGF-1 excess remains a crucial area of investigation to fully dissect the association of acromegaly with cardiovascular disease complications.

Insulin Resistance in Patients With Acromegaly

Acromegaly is characterized by chronic overproduction of growth hormone (GH) that leads to insulin resistance, glucose intolerance and, ultimately, diabetes. The GH-induced sustained stimulation of lipolysis plays a major role not only in the development of insulin resistance and prediabetes/diabetes, but also in the reduction of lipid accumulation, making acromegaly a unique case of severe insulin resistance in the presence of reduced body fat. In the present review, we elucidate the effects of GH hypersecretion on metabolic organs, describing the pathophysiology of impaired glucose tolerance in acromegaly, as well as the impact of acromegaly-specific therapies on glucose metabolism. In addition, we highlight the role of insulin resistance in the development of acromegaly-associated complications such as hypertension, cardiac disease, sleep apnea, polycystic ovaries, bone disease, and cancer. Taken together, insulin resistance is an important metabolic hallmark of acromegaly, which is strongly related to disease activity, the development of comorbidities, and might even impact the response to drugs used in the treatment of acromegaly.

Bringing Cardiovascular Comorbidities in Acromegaly to an Update. How Should We Diagnose and Manage Them?

Patients with acromegaly frequently develop cardiovascular comorbidities, which significantly affect their morbidity and contribute to an increased all-cause mortality. In this regard, the most frequent complications that these patients may encounter include hypertension, cardiomyopathy, heart valve disease, arrhythmias, atherosclerosis, and coronary artery disease. The specific underlying mechanisms involved in the pathophysiology of these comorbidities are not always fully understood, but uncontrolled GH/IGF-I excess, age, prolonged disease duration, and coexistence of other cardio-vascular risk factors have been identified as significant influencing predisposing factors. It is important that clinicians bear in mind the potential development of cardiovascular comorbidities in acromegalic patients, in order to promptly tackle them, and avoid the progression of cardiac abnormalities. In many cases, this approach may be performed using straightforward screening tools, which will guide us for further diagnosis and management of cardiovascular complications. This article focuses on those cardiovascular comorbidities that are most frequently encountered in acromegalic patients, describes their pathophysiology, and suggests some recommendations for an early and optimal diagnosis, management and treatment.

Preclinical markers of atherosclerosis in acromegaly: a systematic review and meta-analysis

OBJECTIVE

Multiple studies investigated preclinical markers of peripheral vascular damage in acromegaly (ACRO) reporting discordant results. The aim of this study was to run a meta-analysis to examine whether intima media thickness (IMT), flow mediated dilation (FMD) and arterial pulse wave velocity (PWV) are affected in acromegalic patients and to assess the impact of effective treatment of growth hormone excess on these outcomes.

STUDY SELECTION

Twenty-seven studies comparing ACRO vs control (CON) populations and active (ACT) vs inactive (INACT) ACRO were included in the meta-analysis.

DATA SYNTHESIS

ACRO compared to CON have higher IMT (ES = 0.83, 95% C.I. 0.35-1.30), p = 0.001, impaired FMD (ES = - 1.59, 95% C.I. - 2.33 to - 0.85, p < 0.0001) and higher PWV (ES = 0.76 95% C.I. 0.37-1.16, p = 0.0001). When patients with ACT vs INACT disease were considered IMT was higher (ES = 0.43, 95% C.I. 0.02-0.84, p = 0.041) and FMD was impaired (ES = - 0.66, 95% C.I. - 1.28 to 0.04, p = 0.038) in ACT patients. Meta-regression analysis of studies comparing IMT in ACT vs INACT acromegalic patients showed a significant and inverse association between the effect size and the percent of hypertensive (p = 0.025) and diabetic (p = 0.041) patients.

CONCLUSIONS

IMT, FMD and arterial stiffness are impaired in acromegaly showing that these patients may be at increased risk of atherosclerosis. In patients with active disease these preclinical markers of atherosclerosis are worse compared to patients with inactive disease but the role of diabetes and hypertension is prevailing on growth hormone excess.

CARDIOVASCULAR COMPLICATIONS OF ACROMEGALY

Acromegaly is associated with increased mortality and decreased life expectancy. Cardiovascular disease is the principal cause of premature mortality in patients with acromegaly, accounting for about 60% of deaths. GH and/or IGF-I exert direct cardiac effects: enhance cardiac contractility, stimulate cardiomyocyte growth, influence calcium influx in cardiomyocytes. Cardiac remodelling is influenced by hypertension and insulin resistance. Among cardiovascular risk factors arterial hypertension, reported in 35% of patients with acromegaly, ranks among most important negative prognostic factors for mortality. Hypertension plays significant role in the development of cardiac hypertrophy, especially in older acromegalic patients and diastolic blood pressure is best predictive factor for cardiac hypertrophy. Therefore, early and aggressive hypertension treatment is essential for prognosis in acromegaly. Other important risk factors are: valvular defects, arrhythmias, endothelial dysfunction, heart failure, lipid abnormalities and coronary artery disease. Numerous studies suggest that patients with acromegaly are under threat of arrhythmias, especially those with structural heart abnormalities. Congestive heart failure as end-stage acromegalic cardiomyopathy occurs usually in older patients, with long-term uncontrolled disease and other cardiovascular and metabolic complications. Relation between acromegaly and coronary artery disease is controversial as it seems to be connected rather with classical cardiovascular risk factors than GH and IGF-1 overexpresion.

Persistent Reduction of Circulating Myeloid Calcifying Cells in Acromegaly: Relevance to the Bone-Vascular Axis

CONTEXT

Acromegaly is a systemic disease characterized by persistent bone pathology and excess cardiovascular mortality. Despite multiple concomitant risk factors, atherosclerosis does not seem to be accelerated in acromegaly.

OBJECTIVE

To compare the levels of circulating myeloid calcifying cells (MCCs), which promote ectopic calcification and inhibit angiogenesis, in individuals with and without acromegaly.

DESIGN

Cross-sectional case-control study.

SETTING

Tertiary ambulatory referral endocrinology center.

PATIENTS

44 acromegalic patients (25 active; 19 inactive), 44 control subjects matched by age, sex, risk factors, and medications, and 8 patients cured of acromegaly.

INTERVENTION

MCCs were measured using flow cytometry based on the expression of osteocalcin (OC) and bone alkaline phosphatase (BAP) on monocytes and circulating CD34+ stem cells.

MAIN OUTCOME MEASURE

Differences in MCCs between patients and controls.

RESULTS

OC+BAP+ MCCs were severely reduced in acromegalic compared with control patients (0.17% ± 0.02% vs 1.00% ± 0.24%; P < 0.001), as were the total OC+ and BAP+ monocytic cells. Patients with inactive acromegaly and those cured of acromegaly displayed persistently reduced levels of MCCs. In the controls, but not acromegalic patients, MCCs were increased in the presence of diabetes or cardiovascular disease. A direct correlation was noted between MCCs and parathyroid hormone (r = 0.61; P < 0.0001), supporting a link between bone biology and MCCs.

CONCLUSIONS

In patients with acromegaly, the levels of MCCs are reduced and remain low, even years after a complete cure. This finding might be related to low atherosclerotic calcification and the persistence of bone pathology after acromegaly remission or cure.

ASSESSMENT OF DIASTOLIC DYSFUNCTION, ARTERIAL STIFFNESS, AND CAROTID INTIMA-MEDIA THICKNESS IN PATIENTS WITH ACROMEGALY

OBJECTIVE

Early diagnosis and treatment of cardiovascular diseases, the most frequent cause of morbidity and mortality in acromegaly, may be an efficient approach to extending the lifespan of affected patients. Therefore, it is crucial to determine any cardiovascular diseases in the subclinical period. The study objectives were to determine markers of subclinical atherosclerosis and asses heart structure and function.

METHODS

This was a cross-sectional, single-center study of 53 patients with acromegaly and 22 age- and sex-matched healthy individuals. Carotid intima-media thickness (CIMT), pulse-wave velocity (PWV), and echocardiographic data were compared between these groups.

RESULTS

CIMT and PWV were higher in the acromegaly group than in the healthy group (P = .008 and P = .002, respectively). Echocardiography showed that left ventricular diastolic dysfunction was present in 11.3% of patients. Left ventricular mass index and left atrial volume index were higher in the patients (P = .016 and P<.001, respectively). No differences in the CIMT, PWV, or echocardiographic measurements were identified between the patients with biochemically controlled and uncontrolled acromegaly and the control group.

CONCLUSION

Our results showed that subclinical atherosclerosis (i.e., CIMT and PWV markers) and heart structure and function were worse in patients with acromegaly than in healthy individuals. Because there were no differences in these parameters between patients with controlled and uncontrolled acromegaly, our results suggest that the structural and functional changes do not reverse with biochemical control.

ABBREVIATIONS

AA = active acromegaly BSA = body surface area CA = biochemically controlled acromegaly CH = concentric hypertrophy CIMT = carotid intima-media thickness DBP = diastolic blood pressure DM = diabetes mellitus ECHO = echocardiography EDV = enddiastolic volume EF = ejection fraction ESV = endsystolic volume GH = growth hormone HC = healthy control HL = hyperlipidemia HT = hypertension IGF-1 = insulin-like growth factor 1 LA = left atrial LAV = left atrial volume LAVI = left atrial volume index LV = left ventricular LVDD = left ventricular diastolic dysfunction LVEF = left ventricular ejection fraction LVH = left ventricular hypertrophy LVMI = left ventricular mass index PWV = pulse-wave velocity RWT = relative wall thickness.

Complications of acromegaly: cardiovascular, respiratory and metabolic comorbidities

Acromegaly is associated with an enhanced mortality, with cardiovascular and respiratory complications representing not only the most frequent comorbidities but also two of the main causes of deaths, whereas a minor role is played by metabolic complications, and particularly diabetes mellitus. The most prevalent cardiovascular complications of acromegaly include a cardiomyopathy, characterized by cardiac hypertrophy and diastolic and systolic dysfunction together with arterial hypertension, cardiac rhythm disorders and valve diseases, as well as vascular endothelial dysfunction. Biochemical control of acromegaly significantly improves cardiovascular disease, albeit completely recovering to normal mainly in young patients with short disease duration. Respiratory complications, represented mainly by sleep-breathing disorders, particularly sleep apnea, and respiratory insufficiency, frequently occur at the early stage of the disease and, although their severity decreases with disease control, this improvement does not often change the indication for a specific therapy directed to improve respiratory function. Metabolic complications, including glucose and lipid disorders, are variably reported in acromegaly. Treatments of acromegaly may influence glucose metabolism, and the presence of diabetes mellitus in acromegaly may affect the choice of treatments, so that glucose homeostasis is worth being monitored during the entire course of the disease. Early diagnosis and prompt treatment of acromegaly, aimed at obtaining a strict control of hormone excess, are the best strategy to limit the development or reverse the complications and prevent the premature mortality.

Cardiovascular comorbidities in acromegaly: an update on their diagnosis and management

Comorbidities related to the cardiovascular system are one of the most prevalent in patients with acromegaly, and contribute to an increased risk of morbidity and all-cause mortality. Specifically, hypertension, cardiomyopathy, heart valve disease, arrhythmias, atherosclerosis, coronary artery disease, and cardiac dysfunction may be frequent findings. Although the underlying physiopathology for each comorbidity may not be fully elucidated, uncontrolled growth hormone/insulin-like growth factor 1 excess, age, prolonged disease duration, and coexistence of other cardio-vascular risk factors are significant influencing variables. A simple diagnostic approach to screen for the presence of these comorbidities may allow prompt treatment and arrest the progression of cardiac abnormalities. In this article, we revise the most prevalent cardiovascular comorbidities and their pathophysiology in acromegalic patients, and we address some recommendations for their prompt diagnosis, management and treatment. Strengths and pitfalls of different diagnostic techniques that are currently being used and how different treatments can affect these complications will be further discussed.

Challenges in the diagnosis and management of acromegaly: a focus on comorbidities

INTRODUCTION

Acromegaly is a rare, insidious disease resulting from the overproduction of growth hormone (GH) and insulin-like growth factor 1 (IGF-1), and is associated with a range of comorbidities. The extent of associated complications and mortality risk is related to length of exposure to the excess GH and IGF-1, thus early diagnosis and treatment is imperative. Unfortunately, acromegaly is often diagnosed late, when patients already have a wide range of comorbidities. The presence of comorbid conditions contributes significantly to patient morbidity/mortality and impaired quality of life.

METHODS

We conducted a retrospective literature review for information relating to the diagnosis of acromegaly, and its associated comorbidities using PubMed. The main aim of this review is to highlight the issues of comorbidities in acromegaly, and to reinforce the importance of early diagnosis and treatment.

FINDINGS AND CONCLUSIONS

Successful management of acromegaly goes beyond treating the disease itself, since many patients are diagnosed late in disease evolution, they present with a range of comorbid conditions, such as cardiovascular disease, diabetes, hypertension, and sleep apnea. It is important that patients are screened carefully at diagnosis (and thereafter), for common associated complications, and that biochemical control does not become the only treatment goal. Mortality and morbidities in acromegaly can be reduced successfully if patients are treated using a multimodal approach with comprehensive comorbidity management.

Arterial properties in acromegaly: relation to disease activity and associated cardiovascular risk factors

PURPOSE

Acromegaly is associated with increased cardiovascular morbidity and mortality when inadequately treated, which may be secondary to associated comorbidities or to direct IGF-1 effects on the cardiovascular system. By using a control group carefully matched for traditional cardiovascular risk factors, we aimed to assess the direct contribution of disease activity and IGF-1 levels to arterial damage as assessed by measurements of arterial stiffness and endothelial function.

METHODS

Twenty-nine subjects with acromegaly (11 males, 52 ± 14 year; 15 active acromegaly) and 24 matched controls underwent evaluation of large and small artery compliance using applanation tonometry, pulse wave velocity (PWV), augmentation index (Alx), carotid ultrasonography intima-media thickness, (IMT) and flow-mediated dilatation (FMD).

RESULTS

IGF-1 expressed as times the upper limit of the normal range (x ULN) was 2.2 ± 1.1 in patients with active disease versus 0.7 ± 0.2 in patients in remission. Irrespective of disease activity, FMD was lower in patients with acromegaly than in control subjects, (3.4 ± 2.7 % in active acromegaly, 4.4 ± 3.3 % in controlled acromegaly and 7.5 ± 3.8 % in controls; p = 0.004). There were no significant differences in PWV, Alx, and IMT between groups. A positive correlation was found between IGF-1× ULN and IMT (r = 0.4; P = 0.02). Asymmetric dimethylarginine (ADMA), a novel cardiovascular risk factor, was positively correlated to arterial stiffness (r = 0.46; p = 0.017) and negatively with small vessel compliance (r = -0.44, p = 0.02).

CONCLUSIONS

Patients with acromegaly have significantly impaired endothelial function as assessed by FMD, but other tested vascular parameters were similar to a control group that was adequately matched for cardiovascular risk factors.

Prevalence of lung structure abnormalities in patients with acromegaly and their relationship with gas exchange: cross-sectional analytical study with a control group

CONTEXT AND OBJECTIVE

Different functional respiratory alterations have been described in acromegaly, but their relationship with pulmonary tissue abnormalities is unknown. The objective of this study was to observe possible changes in lung structure and explain their relationship with gas exchange abnormalities.

DESIGN AND SETTING

Cross-sectional analytical study with a control group, conducted at a university hospital.

METHODS

The study included 36 patients with acromegaly and 24 controls who were all assessed through high-resolution computed tomography of the thorax (CT). Arterial blood gas, effort oximetry and serum growth hormone (GH) and insulin-like growth factor I (IGF-1) were also assessed in the patients with acromegaly.

RESULTS

The abnormalities found in the CT scan were not statistically different between the acromegaly and control groups: mild cylindrical bronchiectasis (P = 0.59), linear opacity (P = 0.29), nodular opacity (P = 0.28), increased attenuation (frosted glass; P = 0.48) and decreased attenuation (emphysema; P = 0.32). Radiographic abnormalities were not associated with serum GH and IGF-1. Hypoxemia was present in seven patients; however, in six of them, the hypoxemia could be explained by underlying clinical conditions other than acromegaly: chronic obstructive pulmonary disease in two, obesity in two, bronchial infection in one and asthma in one.

CONCLUSION

No changes in lung structure were detected through thorax tomography in comparison with the control subjects. The functional respiratory alterations found were largely explained by alternative diagnoses or had subclinical manifestations, without any plausible relationship with lung structural factors.

Three noninvasive methods in the evaluation of subclinical cardiovascular disease in patients with acromegaly: epicardial fat thickness, aortic stiffness and serum cell adhesion molecules

CONTEXT

Several studies have reported increased risk of cardiovascular disease due to early development of endothelial dysfunction and structural vascular changes in patients with acromegaly.

OBJECTIVE

The aim of this study was to evaluate subclinical cardiovascular disease with epicardial fat thickness (EFT), aortic stiffness and serum levels of cell adhesion molecules (CAMs) in patients with acromegaly.

DESIGN

Cross-sectional study.

PATIENTS

Twenty-seven patients with active acromegaly (AA), 13 patients with remission acromegaly (RA) and 37 age- and sex-matched healthy controls were studied.

MEASUREMENTS

Epicardial fat thickness was evaluated by transthoracic echocardiography (TTE). Aortic stiffness (β) index, aortic strain (AoS) and aortic distensibility (AoD) were calculated from the aortic diameters measured by TTE. Serum levels of CAMs such as intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1 and E-selectin were measured.

RESULTS

Epicardial fat thickness was significantly increased in patients with RA and AA as compared to controls 9·71 ± 1·54 and 10·08 ± 1·95 mm vs 5·74 ± 0·92 mm, P < 0·001, respectively). A significant positive correlation was found between the EFT and growth hormone (GH) levels (r = 0·365, P = 0·024). β-index was similarly higher in patients with RA and AA than controls (15·68 ± 7·27 and 11·90 ± 8·24 vs 6·85 ± 2·87, P < 0·001, respectively). AoS and AoD were significantly decreased in patients with RA and AA as compared to the control group (3·81 ± 1·94 and 3·68 ± 1·99 vs 8·19 ± 4·19%, P < 0·001, respectively; and 1·21 ± 0·66 and 1·18 ± 0·63 vs 2·58 ± 1·50, 10(-6) cm(2) /dyn, P < 0·001, respectively). Serum ICAM-1 and VCAM-1 levels were significantly higher in patients as compared to the control group (P < 0·001 vs P = 0·032, respectively). There were no significant differences in EFT, AoD, AoS, β-index and serum CAMs between two patients groups (AA vs RA, P > 0·05). There was a significant negative correlation between E-selectin and AoD (r = -0·45, P = 0·008). In multiple linear regression analysis, EFT was found to be associated with GH levels (β-coefficient = 0·575, P = 0·008).

CONCLUSION

This study suggests that EFT and risk of subclinical cardiovascular disease are increased in patients with acromegaly. Serum GH level is an independent risk factor for EFT.

Pathology, pathophysiology, and treatment strategies of endocrine disorders and their cardiac complications

The cardiovascular system is affected by a multitude of endocrine disorders, including dysfunction of the thyroid, calcium, glucocorticoids, insulin/glucose, and growth hormone axes. Since most of these changes in the cardiovascular system are reversible when treated, early diagnosis is important, as if left untreated, they may become fatal. This review focuses on the pathophysiology, clinical presentation, pathology, and treatment of patients with these endocrine diseases who present with a variety of cardiovascular manifestations. Neuroendocrine tumors presenting with the carcinoid syndrome and their cardiovascular manifestations are also discussed.

The cardiovascular system in growth hormone excess and growth hormone deficiency

The clinical conditions associated with GH excess and GH deficiency (GHD) are known to be associated with an increased risk for the cardiovascular morbidity and mortality, suggesting that either an excess or a deficiency in GH and/or IGF-I is deleterious for cardiovascular system. In patients with acromegaly, chronic GH and IGF-I excess commonly causes a specific cardiomyopathy characterized by a concentric cardiac hypertrophy associated with diastolic dysfunction and, in later stages, with systolic dysfunction ending in heart failure if GH/IGF-I excess is not controlled. Abnormalities of cardiac rhythm and anomalies of cardiac valves can also occur. Moreover, the increased prevalence of cardiovascular risk factors, such as hypertension, diabetes mellitus, and insulin resistance, as well as dyslipidemia, confer an increased risk for vascular atherosclerosis. Successful control of the disease is accompanied by a decrease of the cardiac mass and improvement of cardiac function and an improvement in cardiovascular risk factors. In patients with hypopituitarism, GHD has been considered the under- lying factor of the increased mortality when appropriate standard replacement of the pituitary hormones deficiencies is given. Either childhood-onset or adulthood-onset GHD are characterized by a cluster of abnormalities associated with an increased cardiovascular risk, including altered body composition, unfavorable lipid profile, insulin resistance, endothelial dysfunction and vascular atherosclerosis, a decrease in cardiac mass together with an impairment of systolic function mainly after exercise. Treatment with recombinant GH in patients with GHD is followed by an improvement of the cardiovascular risk factors and an increase in cardiac mass together with an improvement in cardiac performance. In conclusion, acromegaly and GHD are associated with an increased risk for cardiovascular morbidity and mortality, but the control of GH/IGF-I secretion reverses cardiovascular abnormalities and restores the normal life expectancy.

Procalcitonin can be used as a marker of premature atherosclerosis in acromegaly

The objective of the study was to evaluate arterial morphologic changes of early atherosclerosis and changes in procalcitonin (PCT) levels in patients with acromegaly according to disease activity. Thirty-three active and 20 inactive acromegaly patients followed at Endocrinology-Metabolism out-patient clinic of Cerrahpasa Medical Faculty between 2004 and 2008 were included in the study. Twenty gender and age matched healthy subjects were included as the control group. Intima-media thickness (IMT) of the carotid arteries was measured by ultrasonography. Blood was drawn for biochemical tests and the serum concentrations of C-reactive protein (CRP) and PCT. Intergroup analysis revealed no significant differences between Growth hormone (GH), insulin like growth factor-1 (IGF-1), and IMT (P = 0.42, P = 0.47 respectively). No significant differences were found in the fibrinogen, CRP and PCT levels of the acromegaly patients and the subjects in the control group (P = 0.57, P = 0.84, P = 0.68 respectively). In the patients with IMT ≥ 1 mm, PCT (0.4 [IQR: 0.4-0.55]) levels were significantly different from the patients without atherosclerosis (0.06 [IQR: 0.05-0.12], P < 0.001). The correlation between IMT and PCT (P = 0.001, r = 0.47) was more significant than the correlation between IMT and CRP (P = 0.01, r = 0.28). There was a positive correlation between IMT and atherosclerotic risk factors such as age (P = 0.01, r = 0.27) and body mass index (BMI; P = 0.005, r = 0.32). Our results showed that PCT increases before CRP and it can be useful for the assessment of premature atherosclerosis in acromegaly as well.

Growth hormone and the cardiovascular system

Growth hormone (GH) exerts its effects through insulin-like growth factor-1, and although ubiquitous in human tissues, it has a significant role in cardiovascular function. In recent years, there has been a great deal of interest in GH as an etiologic factor in many cardiovascular disease states. Acromegaly, a state of endogenous GH excess, results in myocardial hypertrophy and decreased cardiac performance with increased cardiovascular mortality. Additional insight into the role of excess GH on the cardiovascular system has been gained from data collected in athletes doping with GH. Likewise, GH deficiency is associated with increased mortality, possibly from the associated increase in atherosclerosis, lipid abnormalities, and endothelial dysfunction. However, further research is required to clarify the benefit of GH treatment in both deficient states and in heart failure patients.

Adolescent acromegaly and decreased arterial distensibility despite successful treatment

OBJECTIVE

Cardiovascular complications that are probably related to the loss of arterial elasticity, such as secondary hypertension, occur frequently in patients with acromegaly and may persist after the condition has been treated. The aim of the study was to determine arterial compliance in adolescent patients with acromegaly who had undergone surgery to remove the adenoma in the pituitary gland. This is thought to be the first study on such patients.

PATIENTS

Sixteen patients (nine male, seven female; mean age at diagnosis, 17·6 ± 1·3 years; mean age at time of study, 23·3 ± 3·7 years) who had undergone surgery for acromegaly that was caused by a pituitary adenoma.

MEASUREMENTS

Arterial stiffness was measured by the standardized noninvasive QKd(100-60) method. In addition, blood pressure at rest was measured, ambulatory blood pressure was monitored over a 24-h period and transthoracic echocardiography was performed.

RESULTS

Adolescent patients who had been operated upon for acromegaly showed disadvantageous differences in 24-h ambulatory blood pressure monitoring (systolic blood pressure, P < 0·001; diastolic blood pressure, P < 0·02; mean blood pressure, P < 0·01) and in QKd(100-60) value (194 ± 4 vs 205 ± 5 ms, P < 0·03) compared with controls.

CONCLUSION

Despite successful treatment, the patients showed significantly decreased arterial distensibility as compared with controls, which might explain the observed differences in blood pressure. The findings show that such patients are at increased risk of developing cardiovascular diseases, despite their being youth and the restoration of normal secretion of growth hormone/insulin growth factor.

Enhanced oxidative stress in GH-transgenic rat and acromegaly in humans

BACKGROUND

Excessive oxidative stress plays a causal role in various diseases such as diabetes, hypertension, atherosclerosis, and heart failure. Acromegaly is a pathological condition associated with excess growth hormone (GH) and insulin-like growth factor-I (IGF-I) and a high prevalence of diabetes, hypertension, atherosclerosis, and heart failure; resulting in premature death. We hypothesized that these conditions may be associated with increased oxidative stress.

OBJECTIVE AND METHODS

We explored the oxidative stress levels in the serum and tissues of GH-transgenic rats as an animal model for acromegaly. We also measured the oxidative stress levels in the serum of patients with acromegaly and age-, sex-, and BMI-matched control subjects. We examined the effects of GH and IGF-I on reactive oxygen species (ROS) production in C2C12 myocytes.

RESULTS

The levels of an oxidative stress marker, serum thiobarbituric acid reactive substances (TBARS) were increased in the GH-transgenic rats. Further, tissue oxidative stress damage was enhanced in the cardiomyocytes and vascular smooth muscle cells in the aorta of the GH-transgenic rats. In addition, serum TBARS levels and 8-hydroxy-2-deoxyguanosine (8-OHdG) levels were increased in acromegaly in humans. IGF-I but not GH induced ROS production in C2C12 myocytes in vitro.

CONCLUSIONS

These data indicate that the increased levels of IGF-I are associated with enhanced oxidative stress in rats and humans. In addition, increased ROS may play an important role in the complications and premature death in acromegaly.

Atherosclerotic Risk Factors and Premature Atherosclerosis in Acromegaly Before and After 48 Months of Octreotide-LAR Treatment

We studied premature atherosclerosis with carotid Doppler ultrasonography in active acromegaly before and after treatment. Patients (n = 27) with active acromegaly and 12 age-, gender-, and body mass index-matched healthy individuals were included in the study. Carotid intima–media thickness was decreased significantly in the inactive group after treatment (median: 0.6 mm, interquartile range [IQR]: 0.55-0.80]) when compared with the active group (median: 0.9 mm [IQR: 0.75-1.15], P < .0001), but there was no significant difference between the inactive and control groups. There was a correlation between homeostasis model of assessment–insulin resistance ( P = .01, r = .41) and growth hormone (GH; P < .0001, r = .46). In conclusion, premature atherosclerosis was demonstrated in active acromegaly patients probably as a consequence of insulin resistance and direct vascular effects of GH and/or insulin-like growth factor 1.

Clinical manifestations and diagnosis of acromegaly

Acromegaly and gigantism are due to excess GH production, usually as a result of a pituitary adenoma. The incidence of acromegaly is 5 cases per million per year and the prevalence is 60 cases per million. Clinical manifestations in each patient depend on the levels of GH and IGF-I, age, tumor size, and the delay in diagnosis. Manifestations of acromegaly are varied and include acral and soft tissue overgrowth, joint pain, diabetes mellitus, hypertension, and heart and respiratory failure. Acromegaly is a disabling disease that is associated with increased morbidity and reduced life expectancy. The diagnosis is based primarily on clinical features and confirmed by measuring GH levels after oral glucose loading and the estimation of IGF-I. It has been suggested that the rate of mortality in patients with acromegaly is correlated with the degree of control of GH. Adequately treated, the relative mortality risk can be markedly reduced towards normal.

The effects of long-term growth hormone and insulin-like growth factor-1 exposure on the development of cardiovascular, cerebrovascular and metabolic co-morbidities in treated patients with acromegaly

BACKGROUND

Acromegaly is characterized by the hypersecretion of growth hormone (GH) and insulin-like growth factor-1 (IGF-1). This leads to an increased cardiovascular, cerebrovascular and metabolic morbidity resulting in excess mortality. There is controversy over which biomarker, GH or IGF-1, better predicts this increased morbidity and mortality. The relationship between the cumulative exposure to GH and IGF-1 with co-morbidities in acromegaly has not previously been reported.

OBJECTIVE

To investigate the relationship between the cumulative exposure to GH and IGF-1 with cardiovascular, cerebrovascular and metabolic co-morbidities.

METHODS

Records of 116 acromegalic patients were retrospectively examined. Cardiovascular and cerebrovascular histories, serum GH and IGF-1, fasting glucose and oral glucose tolerance test results, were reviewed for the duration of follow-up. IGF-1 index was calculated by dividing each serum IGF-1 value by the upper limit of reference range for IGF-1. GH and IGF-1 burdens were calculated for each patient by multiplying known disease duration (in years) by mean level of basal GH or IGF-1 index recorded during the patients' entire follow-up.

RESULTS

Patients with abnormal glucose tolerance had a significantly higher mean GH burden compared with euglycaemic patients (P = 0·005). Ischaemic heart disease was also associated with a higher GH burden (P = 0·009) whereas cerebrovascular disease and cardiomyopathy were associated with a significantly higher mean IGF-1 burden (P = 0·018, P = 0·011 respectively).

CONCLUSION

This study identifies associations of raised GH and IGF-1 burden with cardiovascular, cerebrovascular and metabolic complications of acromegaly. Results from this study therefore suggest that consideration of the overall level of GH and IGF-1 exposure may provide important information for the management and surveillance of patients with treated acromegaly.

DNA microarray profiling identified a new role of growth hormone in vascular remodeling of rat ductus arteriosus

The ductus arteriosus (DA), a fetal arterial connection between the pulmonary artery and the aorta, has a character distinct from the adjacent arteries. We compared the transcriptional profiles of the DA and the aorta of Wistar rat fetuses on embryonic day 19 (preterm) and day 21 (near-term) using DNA microarray analyses. We found that 39 genes were expressed 2.5-fold greater in the DA than in the aorta. Growth hormone (GH) receptor (GHR) exhibited the most significant difference in expression. Then, we found that GH significantly promoted migration of DA smooth muscle cells (SMCs), thus enhancing the intimal cushion formation of the DA explants. GH also regulated the expression of cytoskeletal genes in DA SMCs, which may retain a synthetic phenotype in the smooth muscle-specific cytoskeletal genes. Thus, the present study revealed that GH-GHR signal played a role in the vascular remodeling of the DA.

The treatment with growth hormone receptor antagonist in acromegaly: effect on vascular structure and function in patients resistant to somatostatin analogues

BACKGROUND

Acromegaly is known to be associated to vascular damage characterized by an increase of vascular wall thickness and an impairment of vascular function.

AIM

The aim of this study was to evaluate the effect of medical treatment with the GH receptor antagonist pegvisomant on vascular structure and function in acromegalic patients resistant to somatostatin analogues.

PATIENTS

Ten patients (4 males and 6 females, 28-58 yr) and 20 sex-, age-, and body mass index-matched healthy controls entered the study. All patients were treated for 18 months with pegvisomant at doses ranging from 10 to 40 mg/day.

OUTCOME MEASURES

Primary outcome measures were measurement of carotid arteries intima-media thickness (IMT), and brachial arteries flow mediated dilation (FMD); secondary outcome measures were blood pressure, blood glucose and lipids levels.

RESULTS

Carotid arteries maximal IMT was significantly higher in patients than in controls at baseline (1.18±0.59 vs 0.69±0.13, p=0.001) and slightly, but not significantly, decreased after treatment (0.97±0.17). Brachial arteries FMD was significantly lower in patients than controls at baseline (7.5±2.5 vs 13.1±1.4, p<0.001) and significantly increased after treatment (8.8±3.7, p=0.016). Systolic (SBP) and diastolic (DBP) blood pressure values, serum glucose and insulin levels and homeostasis model assessment (HOMA) index were higher, whereas HDL-cholesterol levels were lower in patients than controls at baseline. After treatment, SBP and DBP, as well as serum glucose and insulin levels and HOMA index significantly decreased whereas no significant change was found in serum lipid profile.

CONCLUSIONS

The results of the current study suggested that long-term treatment with pegvisomant induced a slight reduction of carotid arteries wall thickness and a significant improvement of brachial arteries vascular function in patients with acromegaly resistant to somatostatin analogues.

Acromegaly per se does not increase the risk for coronary artery disease

CONTEXT

Information about the risk and course of coronary artery disease (CAD) in acromegaly is limited.

OBJECTIVE

To evaluate CAD risk in acromegalic patients at diagnosis and after successful treatment during follow-up.

SUBJECTS AND METHODS

Twenty-five consecutive patients (age 45.1+/-10.6 years, 15 women) were studied at the time of diagnosis, and 19 patients were re-evaluated after 4.6+/-1.1 years. The European Society of Cardiology (ESC) risk score was calculated, and a cardiac computed tomography was performed for detection and quantification (Agatston score (AS)) of coronary artery calcium (CACs). Fifty age-, sex-, and CAD risk-matched subjects and CAC data from the population-based Heinz Nixdorf Recall (HNR) study served as controls.

RESULTS

In 21 of the 25 patients, the 10-year risk of developing CAD according to the ESC risk score was low (<10%) and high (>20%) in four patients. The AS was lower than in controls (2.6+/-7.9 vs 66+/-182; P=0.014) and less patients had a positive CAC (AS>0) (20 vs 48%, P=0.024), which in the acromegalic patients was less than expected from the HNR study. The AS did not correlate with GH excess or disease duration. In 19 acromegalic patients, who were in remission and re-evaluated after 4.6+/-1.1 years, the ESC risk (P=0.102) and the AS (P=0.173) did not change significantly and no symptomatic CAD event occurred.

CONCLUSION

CAD risk in newly diagnosed acromegalic patients was low and remained stable after successful treatment. CAC was lower than in controls suggesting that GH excess per se does not carry an additional CAD risk.

AMP-activated protein kinase inhibits IGF-I signaling and protein synthesis in vascular smooth muscle cells via stimulation of insulin receptor substrate 1 S794 and tuberous sclerosis 2 S1345 phosphorylation

AMP-activated protein kinase (AMPK) inhibits IGF-I actions, but the mechanism by which AMPK functions is undefined. This study identified signaling events that were induced by AMPK that mediated inhibition of IGF-I-stimulated phosphoinosotide-3-kinase (PI3K) pathway activation. The AMPK activator metformin stimulated AMPK Thr172 phosphorylation and inhibited IGF-I-stimulated phosphorylation of Akt/tuberous sclerosis 2 (TSC2)/mammalian target of rapamycin (mTOR)/p70S6 kinase (p70S6K). Expression of constitutively active forms of AMPK suppressed IGF-I-stimulated activation of Akt/TSC2/mTOR/p70S6K and protein synthesis, whereas AMPK knockdown resulted in enhanced responses to IGF-I. To determine the mechanism by which AMPK inhibited IGF-I signaling, the role of insulin receptor substrate-1 (IRS-1) was examined. Both metformin and constitutively activated AMPK enhanced phosphorylation of IRS-1 Ser794, which led to decreased IRS-1 tyrosine phosphorylation and recruitment of the p85 subunit of PI3K. Overexpression of IRS-1 S794A was associated with increased IGF-I-stimulated IRS-1 tyrosine phosphorylation, p85 association, and protein synthesis. To determine whether other signaling molecules mediated the effect of AMPK, TSC2 function was examined. Cells overexpressing TSC2/S1345A (the site of AMPK phosphorylation) were less responsive to metformin-induced inhibition of p70S6 kinase. These findings are relevant to whole animal physiology because administration of metformin to mice resulted in inhibition of IGF-I-stimulated phosphorylation of Akt/mTOR/p70S6K. In conclusion, AMPK functions to inhibit IGF-I-stimulated PI3K pathway activation through stimulation of IRS-1 serine 794 phosphorylation. Because IGF-I is an important stimulant of the anabolic response, this effect of AMPK could account for part of its inhibitory effect on protein synthesis, thus allowing more efficient energy use by other cellular processes.

Growth hormone deficiency after treatment of acromegaly: a randomized, placebo-controlled study of growth hormone replacement

CONTEXT

The effects of GH replacement therapy in patients who develop GH deficiency (GHD) after cure of acromegaly have not been established in a placebo-controlled study.

OBJECTIVE

The objective of the study was to determine whether GH replacement improves body composition, cardiovascular risk markers and quality of life in patients with GHD and prior acromegaly.

DESIGN

This was a 6-month, randomized, placebo-controlled study.

SETTING

The study was conducted at a clinical translational science center.

STUDY PARTICIPANTS

Participants included 30 subjects with prior acromegaly and current GHD.

INTERVENTION

INTERVENTIONs included GH or placebo.

MAIN OUTCOME MEASURES

Body composition (dual-energy x-ray absorptiometry and cross-sectional computed tomography at L4), cardiovascular risk markers (high-sensitivity C-reactive protein (hsCRP), total, high-density lipoprotein and low-density lipoprotein cholesterol, fibrinogen, and carotid intimal-medial thickness), and quality of life were measured.

RESULTS

The mean GH dose at 6 months was 0.58 +/- 0.26 mg/d. Total fat mass, visceral adipose tissue (-15.3 +/- 18.6 vs. 1.3 +/- 12.5%, P = 0.01), and total abdominal fat decreased, and fat-free mass increased, in the GH vs. placebo group. Mean hsCRP levels decreased, but there was no GH effect on other cardiovascular risk markers. There was no change in glycosylated hemoglobin or homeostasis model assessment insulin resistance index. Quality of life improved with GH. Side effects were minimal.

CONCLUSIONS

This is the first randomized, placebo-controlled study of the effects of GH replacement therapy on body composition and cardiovascular end points in patients who have developed GH deficiency after treatment for acromegaly, a disease complicated by metabolic and body composition alterations and increased cardiovascular risk. GH replacement decreased visceral adipose tissue, increased fat-free mass, decreased hsCRP, and improved quality of life in patients with GHD after cure of acromegaly, with minimal side effects and without an increase in insulin resistance.

Investigation of early atherosclerotic changes in acromegalic patients

BACKGROUND

Functional and morphological changes of endothelium were risk factors for mortality attributed to atherosclerosis. Studies investigating early atherosclerotic alterations and the effect of the treatment of acromegaly on these alterations gave conflicting results.

OBJECTIVE

Surrogate markers of early atherosclerotic changes, i.e. brachial artery flow-mediated dilation (FMD) and carotid artery intima-media-thickness (IMT) in active and inactive acromegalic patients were compared with control subjects matched to patients for age, sex and cardiovascular risk factors to find out the direct effects of growth hormone (GH)/insulin-like growth factor-1 excess.

METHODS

In 14 active acromegalics and their 14 matched controls, 14 inactive acromegalics and their 14 matched controls, carotid artery IMT and FMD of brachial artery were measured. Inactive acromegalics were in remission for at least 1 year.

RESULTS

Active acromegalics had higher IMT than matched controls and inactive acromegalics (0.85 +/- 0.20 mm, 0.64 +/- 1.77 mm, 0.66 +/- 0.20 mm respectively; p < 0.005, p < 0.05) and IMT of inactive acromegalics was not different from their matched controls (0.61 +/- 0.12 mm). FMD was significantly lower in active acromegalics than in matched controls and inactive acromegalics (2.910 +/- 2.00 mm, 6.5 +/- 2.81 mm, 5.68 +/- 2.9 mm respectively; p < 0.005, p < 0.05). FMD of inactive acromegalics was not significantly different from their matched controls (7.96 +/- 3.12 mm). A significant inverse relationship was found between GH and FMD in active acromegalics (r = -0.659, p = 0.010).

CONCLUSION

In active acromegalics, early atherosclerotic changes are not only attributed to the high prevalence of risk factors, but also to the abnormal GH secretion itself.

The cardiovascular phenotype of a mouse model of acromegaly

BACKGROUND

Although, it is accepted that there is an excess of cardiovascular mortality in acromegaly, it is uncertain whether this is due to the direct effects of growth hormone-induced-cardiomyopathy or is a consequence of atherosclerosis secondary to the metabolic syndrome often observed in this condition. Direct comparison of a mouse model of acromegaly to a mouse model of Laron's syndrome allowed us to carry out detailed phenotyping and better understand the role GH plays in the circulatory system.

METHODS AND RESULTS

Transgenic mice that overexpress the growth hormone gene (GH) developed gigantism, including insulin resistance and higher blood pressures commensurate with increased body mass. In these giant mice, the hearts were hypertrophied but haemodynamic studies suggested contractile function was normal. Segments of small arteries mounted in a pressure myograph showed vascular wall hypertrophy but a preserved lumen diameter. Vascular contractile function was normal. Mice in which the GH receptor gene was disrupted or 'knocked out' were dwarf and had low blood pressure, small hearts and blood vessels but a normally functioning circulation. Correlations of body mass with cardiovascular parameters suggested that blood pressure and structural characteristics develop in line with body size.

CONCLUSION

In this transgenic mouse model of acromegaly, there is cardiac and vascular hypertrophy commensurate with GH excess but normal function. Our findings support the contention that the excess mortality in this condition may be due to the development of hypertrophic cardiomyopathy rather than increased rates of atherosclerotic coronary artery disease.

Reduced nitric oxide levels in acromegaly: cardiovascular implications

Acromegaly is characterized by major cardiovascular alterations. Although the underlying mechanisms of these vascular modifications have not been elucidated, recent studies have focused on endothelial dysfunction. Nitric oxide (NO) may contribute to increased vascular resistance, reduced platelet aggregation, inhibition of smooth muscle cell proliferation, and reduction of lipoxygenase activity. At present, no data on NO production in acromegalics are available. The aim of this study was to evaluate the effect of high levels of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) present in acromegaly on NO pathway to investigate the role played by this molecule in the cardiovascular changes experienced by these patients. We studied 13 acromegalics and 12 sex- and age-matched normotensive controls. Platelet NO levels were measured in the supernatant of lysed platelets. Endothelial NO synthase (eNOS) was determined by Western blot analysis of platelets. NO concentrations were significantly reduced in patients (p<0.0001). There were no differences between male and female patients, nor were platelet NO levels and the presence/absence of hypertension related in acromegalics; by contrast, NO concentrations inversely correlated with GH (p=0.03) and IGF-1 (p=0.04) levels, and with disease duration (p=0.04). eNOS protein concentrations were significantly reduced in the platelets of patients compared with controls (p<0.0001). This study demonstrates for the first time a strong reduction in platelet NO concentrations in acromegalic patients due to reduced eNOS expression. Moreover the inverse correlation of NO levels with GH, IGF-1 and disease duration suggests that reduced levels of platelet NO linked to GH excess may contribute to the vascular alterations affecting patients with acromegaly.

Small vessel remodeling and impaired endothelial-dependent dilatation in subcutaneous resistance arteries from patients with acromegaly

CONTEXT

Patients with acromegaly have increased morbidity and mortality, predominantly from cardiovascular disease. Hypertension and diabetes are more prevalent, and both cause small vessel remodeling and endothelial dysfunction.

OBJECTIVE

To understand the structure and function of small arteries in acromegaly, sc blood vessels from gluteal fat biopsies were harvested from 18 patients with active disease (AD; age, 56 +/- 15 yr; 14 males), 23 patients in remission (CD; age, 55 +/- 12 yr; 15 males), and 20 healthy controls (age, 55 +/- 11 yr; 10 males) and examined in vitro using pressure myography.

DESIGN

Contractile responses to cumulative noradrenaline concentrations were recorded and followed by dose-dependent dilator responses to acetylcholine. The acetylcholine protocol was repeated after incubation with a nitric oxide synthase inhibitor (N-nitro-L-arginine methyl ester) and cyclooxygenase inhibitor (indomethacin). After perfusion with Ca(2+)-free physiological saline solution, structural measurements were recorded at varying intraluminal pressures (3-180 mm Hg).

RESULTS

Wall thickness and wall:lumen ratio were increased in AD, reduced with treatment but remained greater in CD than controls. Wall cross-sectional area was increased in AD vs. controls (P < 0.001), decreased with treatment (AD vs. CD, P < 0.001), but remained higher than controls (CD vs. controls, P = 0.015). Growth index was increased in AD (20%) compared to controls (CD, 9%). Contractility was similar in all groups. Endothelial-dependent dysfunction was evident in AD compared with CD (P < 0.001) and controls (P < 0.01). Dilation did not change after N-nitro-L-arginine methyl ester but was impaired after indomethacin incubation.

CONCLUSION

Active acromegaly is associated with hypertrophic remodeling of the vascular wall and embarrassed endothelial function due to reduced nitric oxide and endothelium-derived hyperpolarizing factor bioavailability, both of which may contribute to the early mortality from cardiovascular disease.

Alterations in biomarkers of cardiovascular disease (CVD) in active acromegaly

OBJECTIVES

In acromegalic patients, cardiovascular and metabolic comorbidities contribute to enhance mortality. Available data on the lipoprotein profile of these patients are controversial. Our aim was to characterize the lipoprotein profile and emergent biomarkers of cardiovascular disease in active acromegalic patients in comparison with sex- and age-matched healthy controls.

PATIENTS

Eighteen patients with active acromegaly and 18 controls were studied.

MEASUREMENTS

Glucose levels, hormonal status, lipoprotein profile and C reactive protein (CRP) were evaluated by standardized methods. Cholesteryl ester transfer protein (CETP) and lipoprotein-associated phospholipase A(2 )(Lp-PLA(2)) were measured by radiometric techniques, endothelin-1 and vascular cell adhesion molecule (VCAM)-1 by enzyme-linked immunosorbent assay, and leucocytes CD18, CD49d and CD54 by flow cytometry.

RESULTS

After adjusting for body mass index (BMI), acromegalic patients presented a more atherogenic lipoprotein profile, consisting of higher levels of triglycerides and apolipoprotein B and alterations in the ratios which estimate insulin resistance and atherogenic risk. CETP activity was significantly increased in acromegalic patients as compared to controls (168 +/- 17 vs. 141 +/- 30% per ml h, respectively; P < 0.05). Endothelin-1 levels evidenced an increase in the patients' group (0.9 +/- 0.2 vs. 0.7 +/- 0.2 ng/l, respectively; P < 0.01) and showed positive and significant correlations with GH, IGF-1 and IGFBP-3 (r = 0.45, 0.42 and 0.44, respectively; P < 0.01 for all of them; with BMI as a fixed variable). Lymphocytes from acromegalic patients showed increased CD49d content (282 +/- 59 vs. 246 +/- 48 arbitrary units, respectively; P < 0.05).

CONCLUSIONS

Taken together, the alterations described seem to contribute to constituting a state of higher propensity for the development of atherosclerotic cardiovascular disease, which adds to the presence of specific cardiomyopathy.

Distúrbios cardiovasculares na acromegalia

A acromegalia acarreta uma série de distúrbios ao sistema cardiovascular, decorrentes da exposição crônica a níveis elevados de GH e IGF-1. Estes distúrbios são os principais responsáveis pelo aumento da mortalidade de acromegálicos. Entre as várias formas de acometimento cardiovascular, destaca-se a miocardiopatia acromegálica, entidade caracterizada, inicialmente, pelo estado hiperdinâmico, seguido de hipertrofia ventricular esquerda concêntrica e disfunção diastólica por déficit de relaxamento, culminando com disfunção sistólica e, por vezes, insuficiência cardíaca franca. Além disso, são também relevantes as arritmias, as valvulopatias, sobretudo mitral e aórtica, a cardiopatia isquêmica, a hipertensão e os distúrbios dos metabolismos glicêmico e lipídico. Nesta revisão são abordados os principais aspectos clínicos e prognósticos destas entidades, os efeitos do tratamento da acromegalia sobre elas e as repercussões correspondentes sobre a sobrevida dos pacientes.

Improvement of endothelial dysfunction in acromegaly after transsphenoidal surgery

Flow-mediated vasodilatation (FMD) is a vascular functional test to detect endothelial dysfunction at the early stage of cardiovascular diseases. Patients with active acromegaly have higher morbidity and mortality due to cardiovascular events. To determine whether active acromegaly is associated with endothelial dysfunction, we studied 17 patients with active acromegaly for measurements of FMD, carotid intima-media thickness (IMT) and brachial-ankle pulse wave velocity (baPWV), and other biochemical parameters before and 3 months after transsphenoidal surgery (TSS). Baseline %FMD in patients with active acromegaly was significantly lower than that in age- and sex-matched control subjects. After TSS, the mean %FMD in acromegaly significantly increased from 5.3% to 7.4%; 12 patients had increased %FMD (responders), whereas 5 patients had decreased or unchanged %FMD (non-responders). However, neither carotid IMT nor baPWV changed after TSS. Serum levels of GH, insulin-like growth factor (IGF)-1, total cholesterol, low-density lipoprotein cholesterol (LDL-C), hemoglobin HA(1C), fasting plasma glucose and insulin levels, and homeostasis model assessment (HOMA)-R significantly decreased, whereas high-density lipoprotein cholesterol significantly increased. Responders had significantly lower baseline %FMD than did non-responders and both insulin levels and HOMA-R significantly decreased in responders, but not in non-responders after TSS. Simple regression analysis revealed that the change of %FMD showed a significant negative correlation with that of LDL-C, but not of IGF-1 or GH, in responders. In conclusion, it is suggested that endothelial dysfunction associated with active acromegaly improves soon after TSS, which is related to LDL-C and/or insulin resistance, but not to excess GH and/or IGF-1 itself.

The GH-IGF-I axis and the cardiovascular system: clinical implications

BACKGROUND

GH and IGF-I affect cardiac structure and performance. In the general population, low IGF-I has been associated with higher prevalence of ischaemic heart disease and mortality. Both in GH deficiency (GHD) and excess life expectancy has been reported to be reduced because of cardiovascular disease.

OBJECTIVE

To review the role of the GH-IGF-I system on the cardiovascular system.

RESULTS

Recent epidemiological evidence suggests that serum IGF-I levels in the low-normal range are associated with increased risk of acute myocardial infarction, ischaemic heart disease, coronary and carotid artery atherosclerosis and stroke. This confirms previous findings in patients with acromegaly or with GH-deficiency showing cardiovascular impairment. Patients with either childhood- or adulthood-onset GHD have cardiovascular abnormalities such as reduced cardiac mass, diastolic filling and left ventricular response at peak exercise, increased intima-media thickness and endothelial dysfunction. These abnormalities can be reversed, at least partially, after GH replacement therapy. In contrast, in acromegaly chronic GH and IGF-I excess causes a specific cardiomyopathy: concentric cardiac hypertrophy (in more than two-thirds of the patients at diagnosis) associated to diastolic dysfunction is the most common finding. In later stages, impaired systolic function ending in heart failure can occur, if GH/IGF-I excess is not controlled. Abnormalities of cardiac rhythm and of cardiac valves can also occur. Successful control of acromegaly is accompanied by decrease of the left ventricular mass and improvement of cardiac function.

CONCLUSION

The cardiovascular system is a target organ for GH and IGF-I. Subtle dysfunction in the GH-IGF-I axis are correlated with increased prevalence of ischaemic heart disease. Acromegaly and GHD are associated with several abnormalities of the cardiovascular system and control of GH/IGF-I secretion reverses (or at least stops) cardiovascular abnormalities.

Amelioration of cardiovascular risk factors with partial biochemical control of acromegaly

OBJECTIVE

Complete remission of acromegaly is associated with favourable changes in cardiovascular risk parameters. We evaluated the effects of suboptimal therapy on haemodynamic, metabolic, inflammatory and coagulation cardiovascular risk indices.

DESIGN AND METHODS

Eighteen acromegalic patients on somatostatin analogues, with incomplete biochemical control, were evaluated at diagnosis and 6 months after treatment and compared to 15 healthy age- and body mass index (BMI)-matched controls. Measurements of blood pressure, GH, IGF-I, glucose, insulin, glycated haemoglobin (HbA1c), lipids, apolipoprotein A1 (apoA1), apoB, high-sensitivity C-reactive protein (hs-CRP), fibrinogen, plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator (tPA) and circulating thrombomodulin were performed in all study participants, followed by an oral glucose tolerance test (OGTT). Insulin sensitivity (IS) was expressed by the Matsuda index (OGTT(ISI)).

RESULTS

Partial control of acromegaly resulted in a significant reduction in systolic and diastolic blood pressure, glucose, insulin, HbA1c, total (T-C) and low density lipoprotein cholesterol (LDL-C) and triglyceride levels, and a significant increase in apoA1, high density lipoprotein cholesterol (HDL-C) and OGTT(ISI) compared to pretreatment levels. Plasma fibrinogen and PAI-1 levels fell significantly [respectively (mean +/- SEM), 11.04 +/- 0.41 vs. 10.12 +/- 0.34 micromol/l, P = 0.003 and 9.6 +/- 1.97 vs. 6.55 +/- 1.89 microg/l, P < 0.001]. However, a marked reduction in tPA [median (IQR) 5.1 (2.5-15) vs. 3.4 (2.4-8.6) microg/l, P = 0.031] and an increase in hs-CRP [median (IQR) 0.05 (0.03-0.11) vs. 0.1 (0.06-0.23) mg/l, P < 0.001] were also noted. On treatment, acromegalic patients were comparable to controls, except for OGTT(ISI), lipoprotein(a) [Lp(a)], fibrinogen and tPA and HDL-C levels. Thrombomodulin and apoB levels were not affected by treatment.

CONCLUSIONS

Partial control in disease activity following somatostatin analogues results in significant improvement in a considerable number of cardiovascular risk markers in acromegaly.

Medical consequences of acromegaly: what are the effects of biochemical control?

This chapter discusses the effects of biochemical control of acromegaly on cardiovascular diseases, metabolic complications, respiratory abnormalities, malignancies and bone alterations. Acromegaly is associated with increased morbidity and mortality for cardiovascular and respiratory complications, whereas neoplasms seem to be a minor cause of increased risk of death. Other associated diseases are osteoarthritis, carpal tunnel syndrome, fatigue, visual abnormalities and reproductive disorders. Acromegaly results in premature death because of prolonged elevation of GH an IGF-I levels, and a strong biochemical control improves well-being and restores life expectancy to normal. The main goals of medical treatment of acromegaly include normalization of biochemical markers of disease activity, improvement in signs and symptoms of the disease, removal or reduction of tumor mass and preservation of pituitary function.