Relationship between insulin-like growth factor-I and brain natriuretic peptide in patients with acromegaly after surgery

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.

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.

Common threads in cardiac fibrosis, infarct scar formation, and wound healing

Wound healing, cardiac fibrosis, and infarct scar development, while possessing distinct features, share a number of key functional similarities, including extracellular matrix synthesis and remodeling by fibroblasts and myofibroblasts. Understanding the underlying mechanisms that are common to these processes may suggest novel therapeutic approaches for pathologic situations such as fibrosis, or defective wound healing such as hypertrophic scarring or keloid formation. This manuscript will briefly review the major steps of wound healing, and will contrast this process with how cardiac infarct scar formation or interstitial fibrosis occurs. The feasibility of targeting common pro-fibrotic growth factor signaling pathways will be discussed. Finally, the potential exploitation of novel regulators of wound healing and fibrosis (ski and scleraxis), will be examined.

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.