N-terminal pro-B-type natriuretic peptide in patients with growth hormone disturbances

Serum NT-pro-BNP Levels Predict Cardiovascular Events in Acromegaly Patients

Background Acromegaly is associated with an increased risk of fatal and non-fatal cardiovascular (CV) events. Controlling acromegaly decreases, but does not normalize this risk. Brain natriuretic peptide (BNP) assessment is used in the general population for the diagnosis of heart failure and to predict ischemic recurrences and mortality. This is a retrospective, longitudinal, monocenter study that evaluates the role of serum N-terminal fragment of BNP (NT-pro-BNP) for predicting CV events in acromegaly patients.

Methods Serum NT-pro-BNP levels were measured in 76 patients with acromegaly (23 males, 57.7±1.5 years), and compared with other predictors of CV events. NT-pro-BNP cut-off value discriminating the occurrence of CV events was determined by ROC analysis. CV events were recorded during a follow-up of 78.6±6.4 months.

Results CV events occurred in 9.2% of patients. Mean log(NT-pro-BNP) concentration was higher in patients who experienced CV events than in those who did not (p<0.01) and in patients who died due to CV events than in those who died due to other causes (p<0.01). Based on the ROC curve, a cut-off value of 91.55 pg/mL could predict CV events (OR 19.06). Log(NT-pro-BNP) was lower in surgically treated patients by surgery (p<0.05), and in those cured by neurosurgery (p<0.02).

Conclusions High NT-pro-BNP value is an independent middle-term predictor of fatal or non-fatal CV events in patients with acromegaly. According to this parameter, surgically treated patients show lower CV risk than those managed with medical therapy, especially if the disease is cured.

Acromegaly and Heart Failure

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 in untreated and uncontrolled patients. Additional relevant cardiovascular complications are represented by arterial hypertension, valvulopathies, arrhythmias, and vascular endothelial dysfunction, which, together with the respiratory and metabolic complications, contribute to the development of cardiac disease and the increase cardiovascular risk in acromegaly. Disease duration plays a pivotal role in the determination of acromegalic cardiomyopathy. The main functional disturbance in acromegalic cardiomyopathy is the diastolic dysfunction, observed in 11% to 58% of patients, it is usually mild, without clinical consequence, and the progression to systolic dysfunction is generally uncommon, not seen or observed in less than 3% of the patients. Consequently, the presence of overt CHF is rare in acromegaly, ranging between 1 and 4%, in patients with untreated and uncontrolled disease. Control of acromegaly, induced by either pituitary surgery or medical therapy improves cardiac structure and performance, limiting the progression of acromegaly cardiomyopathy to CHF. However, when CHF is associated with dilative cardiomyopathy, it is generally not reversible, despite the treatment of the acromegaly.

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.

Active acromegaly is associated with decreased hs-CRP and NT-proBNP serum levels: insights from the Belgian registry of acromegaly

OBJECTIVE

Patients with active acromegaly have an increased prevalence of cardiomyopathy and heart failure but a less than expected risk of coronary artery disease, considering the frequent association of diabetes mellitus and hypertension. We examined whether changes in high-sensitive C-reactive protein (hs-CRP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) might contribute to this phenomenon.

DESIGN AND METHODS

Two hundred patients of the Belgian acromegaly registry (AcroBel) were divided in two groups: active disease (IGF1 Z-score >2; n=95) and controlled disease (IGF1 Z-score ≤2; n=105). Serum levels of hs-CRP and NT-proBNP were measured and correlated with BMI, blood pressure, fasting lipids, fasting glucose and insulin, HbA1c, IGF1, interleukin 6 (IL6), adiponectin, and sE-selectin. In a subset of acromegaly patients, hs-CRP, IL6, and NT-proBNP levels were also compared with those/the values of an age-, gender-, and BMI-matched reference group.

RESULTS

Patients with active acromegaly had significantly lower levels of hs-CRP (median (interquartile range), 0.5 mg/l (0.1, 0.9) vs 1.3 mg/l (0.5, 4.1); P<0.001) and NT-proBNP, (47.0 ng/l (26.0, 86.0) vs 71.0 ng/l (43.0, 184.0); P<0.001) compared with patients with controlled acromegaly. Compared with the reference population, hs-CRP was not different in controlled acromegaly but significantly lower in active acromegaly (median, 0.4 mg/l (0.1, 0.8) vs 1.4 mg/l (0.8, 2.9); P<0.001), while NT-proBNP was similar in active acromegaly but significantly higher in controlled acromegaly (66.5 ng/l (40.0, 119.5) vs 50.8 ng/l (26.5, 79.7); P<0.001).

CONCLUSIONS

Patients with active acromegaly have significantly lower values of NT-proBNP and hs-CRP compared with patients with controlled disease and even lower values of hs-CRP compared with control subjects.

[Acromegalic cardiomyopathy]

Acromegaly is an endocrine disease with specific somatic changes due to an excess of growth hormone. The majority of cases are caused by growth hormone producing pituitary tumors. Cardiovascular complications, which can be detected even in the early stages of the disease, are considered as major contributing factors in the increased morbidity and mortality of the patients. In this review authors briefly summarize clinical characteristics of acromegalic cardiomyopathy.

Hypertension-related factors in patients with active and inactive acromegaly

INTRODUCTION: There are several complications of the cardiovascular system caused by acromegaly, especially hypertension. OBJECTIVES: To evaluate hypertension characteristics in patients with cured/controlled acromegaly and with the active disease. PATIENTS AND METHODS: Cross-sectional study of the follow-up of forty-four patients with acromegaly submitted to clinical evaluation, laboratory tests and cardiac ultrasound. Patients with cured and controlled disease were evaluated as one group, and individuals with active disease as second one. RESULTS: Forty-seven percent of the patients had active acromegaly, and these patients were younger and had lower blood pressure levels than subjects with controlled/cured disease. Hypertension was detected in 50% of patients. Subjects with active disease showed a positive correlation between IGF-1 and systolic and diastolic blood pressure levels (r = 0.48, p = 0.03; and r = 0.42, p = 0.07, respectively), and a positive correlation between IGF-1 and urinary albumin excretion (UAE) rates. In patients with active disease, IGF-1 was a predictor of systolic blood pressure, although it was not independent of UAE rate. For individuals with cured/controlled disease, waist circumference and triglycerides were the predictors associated with systolic and diastolic blood pressure. CONCLUSIONS: Our findings suggest that blood pressure levels in patients with active acromegaly are very similar, and depend on excess GH. However, once the disease becomes controlled and IGF-1 levels decrease, their blood pressure levels will depend on the other cardiovascular risk factors.

The GH/IGF-1 Axis and Heart Failure

The growth hormone (GH)/insulin-like growth factor 1 (IGF-1) axis regulates cardiac growth, stimulates myocardial contractility and influences the vascular system. The GH/IGF-1 axis controls intrinsic cardiac contractility by enhancing the intracellular calcium availability and regulating expression of contractile proteins; stimulates cardiac growth, by increasing protein synthesis; modifies systemic vascular resistance, by activating the nitric oxide system and regulating non-endothelial-dependent actions. The relationship between the GH/IGF-1 axis and the cardiovascular system has been extensively demonstrated in numerous experimental studies and confirmed by the cardiac derangements secondary to both GH excess and deficiency. Several years ago, a clinical non-blinded study showed, in seven patients with idiopathic dilated cardiomyopathy and chronic heart failure (CHF), a significant improvement in cardiac function and structure after three months of treatment with recombinant GH plus standard therapy for heart failure. More recent studies, including a small double-blind placebo-controlled study on GH effects on exercise tolerance and cardiopulmonary performance, have shown that GH benefits patients with CHF secondary to both ischemic and idiopathic dilated cardiomyopathy. However, conflicting results emerge from other placebo-controlled trials. These discordant findings may be explained by the degree of CHF-associated GH resistance. In conclusion, we believe that more clinical and experimental studies are necessary to exactly understand the mechanisms that determine the variable sensitivity to GH and its positive effects in the failing heart.

Cardiac effects of 3 months treatment of acromegaly evaluated by magnetic resonance imaging and B-type natriuretic peptides

Long-term treatment of acromegaly prevents aggravation and reverses associated heart disease. A previous study has shown a temporary increase in serum levels of the N-terminal fraction of pro B-type natriuretic peptide (NT-proBNP) suggesting an initial decline in cardiac function when treatment of acromegaly is initiated. This was a three months prospective study investigating short-term cardiac effects of treatment in acromegalic patients. Cardiac function was evaluated by the gold standard method cardiac magnetic resonance imaging (CMRI) and circulating levels of B-type natriuretic peptides (BNP and NT-proBNP). CMRI was performed at baseline and after 3 months of treatment. Levels of IGF-I, BNP and NT-proBNP were measured after 0, 1, 2 and 3 months. Eight patients (5 males and 3 females, mean age 53 ± 12 years (range 30-70)) and 8 matched healthy control subjects were included. Median IGF-I Z-score decreased from 4.5 (range 2.5-6.4) to 2.3 (-0.1 to 3.3). At baseline the patients had increased left ventricle mass index (LVMI) compared to control subjects (ΔLVMI 35 g/m(2) (95% CI 8-63 g/m(2), P = 0.016). After 3 months of treatment there was an increase in end-diastolic volume index EDVI (ΔEDVI 9 mL/m(2) (95% CI 3-14), P = 0.007) and an increase in levels of BNP (median (ranges) 7 (0.58-286) vs. 20 (1-489) pg/mL, P = 0.033) and of NT-proBNP (63 (20-1004) vs. 80 (20-3391) pg/mL, P = 0.027). Assessed by the highly sensitive and precise CMRI method, 3 months treatment of acromegaly resulted in an increase in EDVI, and increased levels of BNP and NT-proBNP suggesting an initial decrease in cardiac function.

N-terminal pro-brain natriuretic peptide in newly diagnosed acromegaly

INTRODUCTION AND AIM

The mechanisms of acromegalic cardiomyopathy are not clearly understood. Brain natriuretic peptide (BNP) and N-terminal fragment of its pro-hormone (NT-proBNP) are released by the cardiac ventricles and increase in heart failure. In the present study, we aimed to evaluate serum NT-proBNP levels in acromegalic patients and determine a relationship between NT-proBNP levels and echocardiographic parameters.

SUBJECTS AND METHODS

Twenty-two newly diagnosed acromegalic patients [mean age 38.85 ± 11.06 yr; body mass index (BMI): 28.51 ± 3.48 kg/m2] and 26 age- and BMI-matched healthy control subjects (mean age 32.9 ± 12.6 yr; BMI: 26.2 ± 5.3 kg/m2) were included in the study. Standard oral glucose tolerance test (OGTT) was performed. Serum NT-proBNP and GH were measured at the beginning of the OGTT (0 min). Body fat analyses were measured by bioelectrical impedance. Echocardiography was used in cardiac evaluations.

RESULTS

The mean NT-proBNP level in the acromegalic group was not significantly different from the control subjects (55.89 ± 46.64 pg/ml in acromegaly vs 28.76 ± 22.13 pg/ml in control subjects). There were no correlations between the serum NTproBNP, GH, and IGF-I levels. Echocardiography revealed significantly increased left ventricular end-diastolic diameter (p=0.008), interventricular septum thickness (p=0.009), left atrium (p=0.029), and right ventricle diameter (p=0.027) in the acromegalic group.

CONCLUSION

NT-proBNP levels were found to be slightly higher in acromegalic patients as an indicator of heart failure, but the increase was not statistically significant. Although these cardiac structural changes in newly diagnosed acromegalic patients are present, the normal level of NT-proBNP shows that NT-proBNP may not be a good indicator in acromegaly.

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.

Serum markers of cardiovascular risk in patients with acromegaly before and after six months of treatment with octreotide LAR

Acromegaly is associated with increased morbidity and mortality from cardiovascular disease. Inflammatory markers, such as C-reactive protein and leucocyte count, haemostatic markers, such as fibrinogen and factor VIII and cardiac hypertrophy marker, B-type natriuretic peptide, have emerged as important cardiovascular risk markers in the general population. The objective of this study was to assess the serum levels of conventional, inflammatory, haemostatic markers and NT-pro BNP in mostly non-diabetic normotensive patients with acromegaly, as well as the effect of 6 months of octreotide LAR therapy on these markers. We studied 12 patients with active acromegaly, 12 patients in whom remission of acromegaly had been achieved by surgery and 12 healthy control subjects matched for age, gender and body mass index. At baseline fasting blood was obtained for measurements of GH, IGF-1, glucose, insulin, lipids, lipoprotein (a), C-reactive protein, leucocyte count, fibrinogen, factor VIII and NT-pro BNP. After baseline evaluation, patients with active acromegaly were treated with octreotide LAR for 24 weeks. At 24 weeks, measurements were repeated as on baseline. Insulin resistance index and fibrinogen levels were higher in patients with active acromegaly than patients and subjects in control groups. CRP, leucocyte count, factor VIII and NT-pro BNP were similar in the three groups. Octreotide LAR reduced GH, IGF-1 and insulin resistance index but did not alter levels of CRP and NT-pro BNP.