Biosynthesis of cardiac natriuretic peptides

Cardiovascular risk evaluation in pregnancy: focus on cardiac specific biomarkers

Despite the evidence demonstrating the clinical utility of cardiac specific biomarkers in improving cardiovascular risk evaluation in several clinical conditions, even the most recent reviews and guidelines fail to consider their measurement in order to enhance the accuracy of the evaluation of cardiovascular risk in pregnant women. The aim of this review article was to examine whether the assay of cardiac specific biomarkers can enhance cardiovascular risk evaluation in pregnant women, first by reviewing the relationships between the physiological state of pregnancy and cardiac specific biomarkers. The clinical relevance of brain natriuretic peptide (BNP)/NT-proBNP and high-sensitivity cardiac troponin I/high-sensitivity cardiac troponin T (hs-cTnI/hs-cTnT) assay in improving cardiovascular risk evaluation is examined based on the results of clinical studies on subjects with normal and those with complicated pregnancy. Finally, the analytical approaches and clinical objectives related to cardio specific biomarkers are advocated in order to allow an early and more accurate evaluation of cardiovascular risk in pregnant women.

Distinct non-ischemic myocardial late gadolinium enhancement lesions in patients with type 2 diabetes

Background

Cardiovascular magnetic resonance imaging (CMR) have described localised non-ischemic late gadolinium enhancement (LGE) lesions of prognostic importance in various non-ischemic cardiomyopathies. Ischemic LGE lesions are prevalent in diabetes (DM), but non-ischemic LGE lesions have not previously been described or systematically studied in DM.

Methods

296 patients with type 2 DM (T2DM) and 25 sex-matched control subjects underwent echocardiography and CMR including adenosine-stress perfusion, T₁-mapping and LGE.

Results

264 patients and all control subjects completed the CMR protocol. 78.4% of patients with T2DM had no LGE lesions; 11.0% had ischemic LGE lesions only; 9.5% had non-ischemic LGE lesions only; and 1.1% had both one ischemic and one non-ischemic lesion. The non-ischemic LGE lesions were situated mid-myocardial in the basal lateral or the basal inferolateral part of the left ventricle and the affected segments showed normal to high wall thickness and normal contraction. Patients with non-ischemic LGE lesions in comparison with patients without LGE lesions had increased myocardial mass (150 ± 34 vs. 133 ± 33 g, P = 0.02), average E/e’(9.9 IQR8.7–12.6 vs. 8.8 IQR7.4–10.7, P = 0.04), left atrial maximal volume (102 IQR84.6–115.2 vs. 91 IQR75.2–100.0 mL, P = 0.049), NT-proBNP (8.9 IQR5.9–19.7 vs. 5.9 IQR5.9–10.1 µmol/L, P = 0.02) and high-sensitive troponin (15.6 IQR13.0–26.1 vs. 13.0 IQR13.0–14.6 ng/L, P = 0.007) and a higher prevalence of retinopathy (48 vs. 25%, P = 0.009) and autonomic neuropathy (52 vs. 30.5%, P = 0.005).

Conclusion

A specific LGE pattern with lesions in the basal lateral or the basal inferolateral part of the left ventricle was found in patients with type 2 diabetes.

Trial registrationhttps://www.clinicaltrials.gov. Unique identifier: NCT02684331.

Joint Associations of Obesity and NT-proBNP With the Incidence of Atrial Fibrillation in the ARIC Study

Background

Circulating NT‐proBNP (N‐terminal pro‐B‐type natriuretic peptide) levels, a well‐known indicator of atrial wall stress and remodeling, inversely correlate with body mass index. Both are strongly predictive of atrial fibrillation (AF). Their potential interaction in relation to incident AF, however, has not been explored.

Methods and Results

In total, 9556 participants of the ARIC (Atherosclerosis Risk in Communities) study who had 2 measurements of NT‐proBNP and no baseline AF or heart failure were followed from 1996 to 1998 through 2016 for the occurrence of incident AF. Participants were categorized as obese (body mass index ≥30) and nonobese (body mass index <30) and by NT‐proBNP levels (using the median of 68.2 pg/mL as the cutoff). Over a median follow‐up of 18.3 years, we identified 1806 incident cases of AF. Analysis using multivariable Cox regression models showed that obese participants with high NT‐proBNP levels at visit 4 had a higher adjusted risk of incident AF (hazard ratio: 3.64; 95% CI, 3.15–4.22) compared with nonobese individuals with low NT‐proBNP levels. The association of obesity with AF risk was not modified by NT‐proBNP levels (P=0.46 for interaction). Increasing BNP among participants from 1990–1992 to 1996–1998 was associated with increased AF risk. After further adjustment for clinical risk factors and medications, results were similar.

Conclusions

Individuals who had both elevated body mass index and NT‐proBNP and were free of clinically recognized heart failure were at higher risk of AF development. Those who experienced an increase in NT‐proBNP levels between visits 2 and 4 were at higher risk of AF.

Inverse Correlation of Venous Brain Natriuretic Peptide Levels with Body Mass Index Is due to Decreased Production

OBJECTIVE

The aim of this paper was to study the association between body mass index (BMI) and coronary sinus (CS) brain natriuretic peptide (BNP) levels in patients with heart failure and reduced systolic function (HFrEF).

BACKGROUND

There is an inverse relationship between systemic venous BNP (V-BNP) levels and BMI in patients with HFrEF. It is unclear whether this finding is due to decreased production or due to an increased metabolism of BNP. Since CS-BNP levels reflect BNP production, we hypothesized that assessing the correlation of CS-BNP levels with BMI would provide insight into the mechanism of this inverse relationship of V-BNP and BMI.

METHODS

We prospectively enrolled 54 subjects with HFrEF who were to undergo cardiac resynchronization device implantation. CS-BNP, V-BNP, and arterial BNP (A-BNP) levels were measured during the implant procedure. Subjects were divided into 2 groups based on their BMI (group 1: BMI <30 and group 2: BMI ≥30).

RESULTS

The mean age of the overall study group was 64 ± 10 years. Average BMI for group 1 was 25.8 ± 2.8 and 36.8 ± 4.6 for group 2 (p < 0.03). A history of hypertension was present in 55% (n = 26) of the subjects, while diabetes was reported in 31% (n = 15). Serum creatinine was 1.0 ± 0.2 mg/dL and TSH 2.1 ± 1.4 mIU/L. 79% of the subjects were receiving β-blockers, while 94% were receiving angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. The mean CS-BNP, V-BNP, and A-BNP levels in group 2 were significantly lower than in group 1 (286.2 ± 170.5 vs. 417.5 ± 247.5 pg/mL, p = 0.04; 126.6 ± 32.5 vs. 228 ± 96.4 pg/mL, p = 0.01; and 151.9 ± 28.6 vs. 242 ± 88.8 pg/mL, p = 0.04, respectively). Univariate analysis and multivariate regression adjusted for age, diabetes mellitus, sex, glomerular filtration rate, and left atrial size confirmed BMI as an independent predictor of CS-BNP levels (β = -0.372, p = 0. 03) in our study.

CONCLUSIONS

In this study, we demonstrate an inverse relationship between CS-BNP levels and BMI in patients with HFrEF. These findings suggest that the previously established inverse relationship between V-BNP and BMI is due to a decreased cardiac production of BNP in obese patients rather than from increased peripheral metabolism.

Admission hypoxia-inducible factor 1α levels and in-hospital mortality in patients with acute decompensated heart failure

BACKGROUND

Hypoxia-inducible factor 1 (HIF-1) is a critical regulator for cellular oxygen balance. Myocardial hypoxia can induce the increased expression of HIF-1α. Our goals were to evaluate the value of HIF-1α in predicting death of patients with acute decompensated heart failure (ADHF) and describe the in vivo relationship between serum HIF-1α and N-terminal-pro-brain natriuretic peptide (NT-proBNP) levels.

METHOD

We included 296 patients who were consecutively admitted to the emergency department for ADHF. The primary end point was in-hospital death. The patients were categorized as HFrEF (patients with reduced systolic function) and HFpEF (patients with preserved systolic function) groups.

RESULTS

In our patients, the median admission HIF-1α level was 2.95 ± 0.85 ng/ml. The HIF-1α level was elevated significantly in HFrEF patients and deceased patients compared with HFpEF patients and patients who survived. The HIF-1α level was positively correlated with NT-proBNP and cardiac troponin T levels, and negatively correlated with left ventricular ejection fraction and systolic blood pressure. Kaplan-Meier curves revealed a significant increase in in-hospital mortality in ADHF patients with higher HIF-1α levels. Multivariable Cox regression analysis showed that HIF-1α levels were not correlated with the short-term prognosis of ADHF patients.

CONCLUSIONS

This is the first study to evaluate the circulating levels of HIF-1α in ADHF patients. Serum HIF-1α levels may reflect a serious state in patients with ADHF. Due to the limitations of the study, serum HIF-1α levels were not correlated with the in-hospital mortality based on regression analysis. Further studies are needed to demonstrate the diagnostic and/or prognostic role of HIF-1α as a risk biomarker in patients with ADHF.

Obesity and natriuretic peptides, BNP and NT-proBNP: mechanisms and diagnostic implications for heart failure

Many advances have been made in the diagnosis and management of heart failure (HF) in recent years. Cardiac biomarkers are an essential tool for clinicians: point of care B-type natriuretic peptide (BNP) and its N-terminal counterpart (NT-proBNP) levels help distinguish cardiac from non-cardiac causes of dyspnea and are also useful in the prognosis and monitoring of the efficacy of therapy. One of the major limitations of HF biomarkers is in obese patients where the relationship between BNP and NT-proBNP levels and myocardial stiffness is complex. Recent data suggest an inverse relationship between BNP and NT-proBNP levels and body mass index. Given the ever-increasing prevalence of obesity world-wide, it is important to understand the benefits and limitations of HF biomarkers in this population. This review will explore the biology, physiology, and pathophysiology of these peptides and the cardiac endocrine paradox in HF. We also examine the clinical evidence, mechanisms, and plausible biological explanations for the discord between BNP levels and HF in obese patients.

Depletion of proBNP1-108 in patients with heart failure prevents cross-reactivity with natriuretic peptides

BACKGROUND

After synthesis by cardiomyocytes, precursor proBNP1-108 is cleaved into NT-proBNP and BNP. Recently, cross-reactivity between these assays was discussed. The aim of this study was to characterize the cross-reactivities, through a new biochemical innovative approach consisting in the total depletion of the circulating proBNP1-108 in patients with heart failure (HF).

METHODS

This prospective study included 180 patients with chronic HF. BNP and NT-proBNP were dosed with commercial kits. ProBNP1-108 was determined using an ELISA research assay specific to the precursor. ProBNP1-108 depletion was performed by immunocapture with a specific antibody targeting exclusively the ProBNP1-108 hinge region. ProBNP1-108, BNP and NT-proBNP levels were determined before and after depletion using this process in HF patients.

RESULTS

Mean age was 74.34 +/-12.5 y, and 69% of patients were males. NYHA classes II and III were the most frequent (32% and 45% respectively). Before depletion, ProBNP1-108, NT-proBNP and BNP levels were 316.8+/-265.9 pg/ml; 6,054.0+/-11,539 pg/ml and 684.3+/-82.1 pg/ml respectively, and were closely correlated with NHYA classes. After immuno-depletion, proBNP1-108 was decreased in mean by 96% (p<0.0001), BNP by 53% (p<0.0001) and NT-proBNP by 5%. The relationship between BNP or NT-proBNP and NHYA classes remained unchanged.

CONCLUSION

Current BNP and NT-proBNP assays measured as well proBNP molecule. This cross reactivity percentage has been controversial. Thanks to the removal of circulating proBNP1-108 with our immunodepletion process, we are now able to assess the remaining "true" BNP and NT-proBNP molecules and further evaluate their clinical relevance.

Diagnostic, prognostic and therapeutic relevance of B-type natriuretic hormone and related peptides in children with congenital heart diseases

The aim of this article is to review the diagnostic and prognostic relevance of measurement of brain natriuretic peptide (BNP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) in pediatric patients with congenital cardiac diseases (CHD). A computerized literature search in the National Library of Medicine using the keywords "BNP assay" and "NT-proBNP assay"+neonate/s and newborn/s was performed. Next, we refined the analysis to include only the studies specifically designed to evaluate the clinical usefulness of BNP and NT-proBNP measurements in children with CHD. Several authors suggested that BNP/NT-proBNP is clinically helpful as a diagnostic and prognostic marker for children with suspected CHD. BNP values are age dependent, even in paediatric populations. Unfortunately, accurate reference values for BNP and NT-proBNP for neonatal ages have only recently become available. As a result, the lack of homogenous and accurate decisional levels in the neonatal period greatly limits the clinical impact of the BNP assay, and also contributed to the production of conflicting results. Regardless of age, there is great variability in BNP/NT-proBNP values among CHD characterized by different hemodynamic and clinical conditions. In particular, cardiac defects characterized by left ventricular volume and pressure overload usually show a higher BNP response than CHD which is characterized by right ventricular volume or pressure overload. BNP and NT-proBNP may be considered helpful markers in the integral clinical approach for patients with CHD. Measurement of BNP cannot replace cardiac imaging (including echocardiography, angiography and magnetic resonance), but provide independent, low cost and complementary information for the evaluation of cardiac function and clinical status.