Contribution of extracardiac factors to the inconsistency between plasma B-type natriuretic peptide levels and the severity of pulmonary congestion on chest X-rays in the diagnosis of heart failure

Clearing the Congestion: Chest Radiography and BNP to Rule-out Congestive Heart Failure

PURPOSE

Ruling out congestive heart failure (CHF) is clinically important in Emergency Department (ED) patients. Normal serum brain natriuretic peptide (BNP) represents an important reference standard for excluding CHF. Results of chest radiographs (CXR) are also considered and, when discordant with BNP levels, may result in a clinical dilemma. The present study was designed to elucidate factors associated with CHF on CXR in an ED cohort with normal BNP.

MATERIALS AND METHODS

All adults at our urban health system's EDs who underwent CXR within 24 hours and had a normal BNP (<300 pg/mL) within 24 hours of CXR were retrospectively identified. Of these, 0.9% (8/862) had equivocal CXRs and was excluded. Demographics, comorbidities, CXR report results for CHF, and portable technique were noted. Logistic regression was used to assess factors that are associated with the presence of CHF on CXR.

RESULTS

The study cohort comprised 854 patients (433 men, mean age 60.99±15.30) with normal BNP; 91.5% (781/854) had no CHF on CXR and 8.5% (73/854) had CHF. Patients with CHF on CXR had a higher body mass index (32.9 vs. 29.8 kg/m 2 , P =0.0205) were more likely to have a history of CHF or diabetes with complications (OR: 2.72 and 2.53, respectively), had higher serum BNP levels (median 164 vs. 98 pg/mL, P =4.91×10 -5 ), and underwent portable examination more frequently (86.3% vs. 57.5%, OR: 4.65).

CONCLUSIONS

Normal serum BNP was concordant with CXR results, adding diagnostic confidence in ruling out CHF in a large majority of ED patients. A higher body mass index, history of CHF, and diabetes with complications and portable CXR technique were associated with CHF on CXR among the minority with normal BNP.

Disproportionately low BNP levels in patients of acute heart failure with preserved vs. reduced ejection fraction

BACKGROUND

B-type natriuretic peptide (BNP) has been widely used for the diagnosis of heart failure, its severity, and prognosis. However, little is known about factors related to disproportionately low BNP levels even during acute heart failure conditions.

METHODS AND RESULTS

Among 424 patients hospitalized for acute heart failure, we categorized the patients into the HFpEF (LVEF > 50%) or HFrEF (LVEF ≤ 50%) group and subdivided them into disproportionately low BNP (LB) group and high BNP (HB) group using a cut-off BNP level of 200 pg/mL at admission. The proportion of patients with LB was higher in the HFpEF group (22.2%) than in the HFrEF group (10.9%, p = 0.002). Patients with LB had a high BMI, lower blood pressure, and history of previous cardiovascular surgery in the HFpEF group, while patients in the HFrEF group had a high BMI and smaller left ventricular end-diastolic volume index. Furthermore, presence of LB in the HFrEF group was related to good prognosis, but LB in the HFpEF group was an indicator of poor prognosis as HB group.

CONCLUSIONS

The factors associated with LB were different between the HFpEF and HFrEF groups. LB was related to good prognosis in HFrEF, but not in HFpEF.

Association between plasma B-type natriuretic peptide and anaemia in heart failure with or without ischaemic heart disease: a retrospective study

OBJECTIVES

Anaemia is a risk of worsening heart failure. However, anaemia sometimes remains undetected because the superficial cardiac function does not precisely reflect the adverse impact of anaemia. Plasma B-type natriuretic peptide (BNP) could be helpful in these cases. However, the direct anaemic effects on BNP remain unknown. Herein, we compared the direct effect of anaemia on BNP and left ventricular ejection fraction (LVEF) using an advanced statistical procedure.

DESIGN

A retrospective study.

SETTING

Secondary care (cardiology), single-centre study.

PARTICIPANTS

The study consisted of 3756 inpatients, including 684 without ischaemic heart disease (IHD) and 3072 with IHD.

PRIMARY AND SECONDARY OUTCOME MEASURES

Relationship between plasma BNP levels and LVEF values.

RESULTS

A path model was constructed to simultaneously examine the adverse impact of anaemia on LVEF and plasma BNP, allowing for renal function. The path model revealed that LVEF increased in response to low haemoglobin (Hb), and the phenomenon was prominent in non-IHD (standardised regression coefficients (St.β): -0.264, p<0.001) rather than in IHD (St.β: 0.015, p=0.531). However, the response of BNP was commonly observed in both groups (non-IHD St.β: -0.238, IHD St.β: -0.398, p<0.001, respectively). Additionally, this study showed a direct link between low estimated glomerular filtration rate and high BNP independently of LVEF. Incrementally, Bayesian structural equation modelling in covariance structure analysis clearly supported this result. The scatter plots and simple regression analysis revealed that an adequate blood supply was approximately Hb 110 g/L and over in the non-IHD patients, whereas blood was not supplied in sufficient quantities even by Hb 130 g/L in patients with IHD.

CONCLUSION

The current study demonstrated that anaemia was a substantial risk for worsening cardiac overload as estimated by plasma BNP. The anaemic response of LVEF likely changed depending on underlying cardiac disorders (IHD or not). However, the response of BNP was robustly observed.

High Serum Uric Acid is Highly Associated with a Reduced Left Ventricular Ejection Fraction Rather than Increased Plasma B-type Natriuretic Peptide in Patients with Cardiovascular Diseases

High serum uric acid (UA) has been reported to be associated with left ventricular (LV) dysfunction; however, the relationship between UA and plasma B-type natriuretic peptide (BNP), a sensitive biomarker of heart failure, is still unclear. This study investigated their relationship to provide an accurate assessment of high UA. The study patients consisted of 3,077 subjects who underwent cardiac catheterization because of various cardiovascular disorders. Since the explanatory factors of multiple regression analysis were mostly confounding with each other, subgroup analysis was performed by quartering the study population using the respective risk factors and by covariance structure analysis. This analysis revealed that UA was almost always well associated with a reduced LV ejection fraction (LVEF), but generally not with BNP. UA was significantly associated with BNP in lean aged females, but not in obese adolescent males, although LVEF was significantly reduced in response to a high UA in both groups. A high UA is a direct risk factor for cardiac dysfunction from the perspective of BNP; however, augmentation of BNP in response to a high UA would likely be restricted among obese adolescent males. On the other hand, the observed LV systolic dysfunction, such as LVEF, reflects a high UA on an almost constant basis.

Associations between Left Ventricular Cavity Size and Cardiac Function and Overload Determined by Natriuretic Peptide Levels and a Covariance Structure Analysis

The effects of left ventricular (LV) cavity size on cardiac function and overload have not yet been fully elucidated. We performed a covariance structure analysis and drew theoretical path models to clarify the effects of hemodynamic parameters on the stroke volume index (SVI) as a marker of cardiac function and on the plasma B-type natriuretic peptide (BNP) level as a marker of cardiac overload. We simultaneously measured various hemodynamic parameters and the BNP levels during cardiac catheterization in 1,715 inpatients of our institution. The current path models tested the validity of the Frank-Starling law in patients with heart failure using the SVI, the LV end-systolic volume index (LVESVI) and the LV end-diastolic volume index (LVEDVI). Using the BNP levels, the path models clearly demonstrated that LVESVI substantially augmented cardiac overload, whereas LVEDVI palliated this parameter. These volume indices exerted opposite effects on cardiac function and overload. These results advance the understanding of the relationships between LV cavity size and both cardiac function and overload and indicate the increasing importance of LV diastolic volume in heart failure and the utility of LVESVI as an important marker of cardiac remodeling for further relevant studies.

Manifold implications of obesity in ischemic heart disease among Japanese patients according to covariance structure analysis: Low reactivity of B-type natriuretic peptide as an intervening risk factor

Background/Objectives

Obesity is believed to be one of the major risk factors for cardiovascular disease in Western countries. However, the effects of obesity should be continuously examined in the Japanese population because the average bodily habitus differs among countries. In this study, we collectively examined the significance of obesity and obesity-triggered risk factors including the low reactivity of B-type natriuretic peptide (BNP), for ischemic heart disease (IHD) in Japanese patients.

Methods and results

The study patients consisted of 1252 subjects (IHD: n = 970; non-IHD: n = 282). Multiple logistic regression analysis revealed that dyslipidemia, hypertension, diabetes, and the low reactivity of BNP were significant risk factors for IHD, but body mass index (BMI) was not. A theoretical path model was proposed by positioning BMI at the top of the hierarchical model. Exploratory factor analysis revealed that BMI did not play a causative role in IHD (P = NS). BMI was causatively linked to other risk factors (P<0.001 for hypertension; P<0.001 for dyslipidemia; P<0.001 for HbA1c; P<0.001 for LogBNP), and these factors played a causative role in IHD (P<0.001 for hypertension; P<0.001 for dyslipidemia; P<0.001 for HbA1c; P<0.001 for LogBNP). The intrinsic power of the low reactivity of BNP induced by high BMI on the promotion of IHD was fairly potent.

Conclusion

This study demonstrated that obesity per se is not a strong risk factor for IHD in Japanese patients. However, several important risk factors triggered by obesity exhibited a causative role for IHD. The low reactivity of BNP is a substantial risk factor for IHD.

Point-of-Care Multi-Organ Ultrasound Improves Diagnostic Accuracy in Adults Presenting to the Emergency Department with Acute Dyspnea

Introduction

Determining the etiology of acute dyspnea in emregency department (ED) patients is often difficult. Point-of-care ultrasound (POCUS) holds promise for improving immediate diagnostic accuracy (after history and physical), thus improving use of focused therapies. We evaluate the impact of a three-part POCUS exam, or “triple scan” (TS) – composed of abbreviated echocardiography, lung ultrasound and inferior vena cava (IVC) collapsibility assessment – on the treating physician’s immediate diagnostic impression.

Methods

A convenience sample of adults presenting to our urban academic ED with acute dyspnea (Emergency Severity Index 1, 2) were prospectively enrolled when investigator sonographers were available. The method for performing components of the TS has been previously described in detail. Treating physicians rated the most likely diagnosis after history and physical but before other studies (except electrocardiogram) returned. An investigator then performed TS and disclosed the results, after which most likely diagnosis was reassessed. Final diagnosis (criterion standard) was based on medical record review by expert emergency medicine faculty blinded to TS result. We compared accuracy of pre-TS and post-TS impression (primary outcome) with McNemar’s test. Test characteristics for treating physician impression were also calculated by dichotomizing acute decompensated heart failure (ADHF), chronic obstructive pulmonary disease (COPD) and pneumonia as present or absent.

Results

57 patients were enrolled with the leading final diagnoses being ADHF (26%), COPD/asthma (30%), and pneumonia (28%). Overall accuracy of the treating physician’s impression increased from 53% before TS to 77% after TS (p=0.003). The post-TS impression was 100% sensitive and 84% specific for ADHF.

Conclusion

In this small study, POCUS evaluation of the heart, lungs and IVC improved the treating physician’s immediate overall diagnostic accuracy for ADHF, COPD/asthma and pneumonia and was particularly useful to immediately exclude ADHF as the cause of acute dyspnea.

INTERACTING DISCIPLINES: Cardiac natriuretic peptides and obesity: perspectives from an endocrinologist and a cardiologist

Since their discovery in 1981, the cardiac natriuretic peptides (cNP) atrial natriuretic peptide (also referred to as atrial natriuretic factor) and brain natriuretic peptide have been well characterised in terms of their renal and cardiovascular actions. In addition, it has been shown that cNP plasma levels are strong predictors of cardiovascular events and mortality in populations with no apparent heart disease as well as in patients with established cardiac pathology. cNP secretion from the heart is increased by humoral and mechanical stimuli. The clinical significance of cNP plasma levels has been shown to differ in obese and non-obese subjects. Recent lines of evidence suggest important metabolic effects of the cNP system, which has been shown to activate lipolysis, enhance lipid oxidation and mitochondrial respiration. Clinically, these properties lead to browning of white adipose tissue and to increased muscular oxidative capacity. In human association studies in patients without heart disease higher cNP concentrations were observed in lean, insulin-sensitive subjects. Highly elevated cNP levels are generally observed in patients with systolic heart failure or high blood pressure, while obese and type-2 diabetics display reduced cNP levels. Together, these observations suggest that the cNP system plays a role in the pathophysiology of metabolic vascular disease. Understanding this role should help define novel principles in the treatment of cardiometabolic disease.

The plasma B-type natriuretic peptide levels are low in males with stable ischemic heart disease (IHD) compared to those observed in patients with non-IHD: a retrospective study

Objective

Although the plasma B-type natriuretic peptide (BNP) level is a marker of heart failure, it is unclear whether BNP per se plays a pivotal role for pathogenic mechanisms underlying the development of ischemic heart disease (IHD). In this study, we retrospectively examined the plasma BNP levels in stable patients with IHD and compared to stable patients with cardiovascular diseases other than IHD.

Methods

The study population was 2088 patients (1698 males and 390 females) who were admitted to our hospital due to IHD (n = 1,661) and non-IHD (n = 427) and underwent cardiac catheterization. Measurements of the hemodynamic parameters and blood sampling were performed.

Results

The plasma BNP levels were significantly lower in the IHD group than in the non-IHD group (p<0.001). The multiple regression analysis examining the logBNP values showed that age, a male gender, low left ventricular ejection fraction, low body mass index, serum creatinine, atrial fibrillation and IHD per se were significant explanatory variables. When the total study population was divided according to gender, the plasma BNP levels were found to be significantly lower in the IHD group than in the non-IHD group among males (p<0.001), but not females (p = NS). Furthermore, a multiple logistic regression analysis of IHD showed the logBNP value to be a significant explanatory variable in males (regression coefficient: −0.669, p<0.001), but not females (p = NS).

Conclusions

The plasma BNP levels were relatively low in stable patients with IHD compared with those observed in stable patients with non-IHD; this tendency was evident in males. Perhaps, the low reactivity of BNP is causally associated with IHD in males. We hope that this study will serve as a test of future prospective studies.

Dual-energy CT pulmonary angiography in patients with suspected pulmonary embolism: value for the detection and quantification of pulmonary venous congestion

OBJECTIVE

To evaluate if vascular and pulmonary parenchymal enhancement values in dual-energy (DE) CT pulmonary angiography (CTPA) can suggest the diagnosis of pulmonary congestion.

METHODS

DE-CTPA images of 90 out of 1321 patients negative for pulmonary embolism showed signs of congestive heart failure. We measured DE-derived pulmonary parenchymal [perfused blood volume (PBV)], pulmonary artery (PA) and left atrium (LA) enhancement values in these patients and in 142 control patients. Enhancement values were compared between the populations and correlated with serum values of B-type natriuretic peptide (BNP) and proBNP, where available.

RESULTS

No significant difference of PBV but significant differences of mean PA and LA enhancement and individual enhancement differences (PA - LA) were found between the populations. PA - LA was higher in patients with elevated BNP and proBNP and was positively correlated with these values. Receiver operating characteristic analysis revealed a moderate discriminatory power of the PA - LA difference for the presence of cardiac biomarker elevations.

CONCLUSION

PBV in DE-CTPA is not altered in patients with signs of congestive heart failure. However, differences in enhancement values in the pre- and post-pulmonary vessels were found in comparison with the control population.

ADVANCES IN KNOWLEDGE

Altered pulmonary vascular haemodynamics in pulmonary venous congestion are not reflected in dual-energy-derived PBV maps. In the diagnosis of left heart failure in patients with chest pain and dyspnoea, density measurements in the pulmonary artery and in the left atrium in CTPA images may be a helpful diagnostic tool.

Cardiac tamponade as an independent condition affecting the relationship between the plasma B-type natriuretic peptide levels and cardiac function

Plasma B-type natriuretic peptide (BNP) is finely regulated by the cardiac function and several extracardiac factors. Therefore, the relationship between the plasma BNP levels and the severity of heart failure sometimes seems inconsistent. The purpose of the present study was to investigate the plasma BNP levels in patients with cardiac tamponade and their changes after pericardial drainage. This study included 14 patients with cardiac tamponade who underwent pericardiocentesis. The cardiac tamponade was due to malignant diseases in 13 patients and uremia in 1 patient. The plasma BNP levels were measured before and 24-48 h after drainage. Although the patients reported severe symptoms of heart failure, their plasma BNP levels were only 71.2 ± 11.1 pg/ml before drainage. After appropriate drainage, the plasma BNP levels increased to 186.0 ± 22.5 pg/ml, which was significantly higher than that before drainage (P = 0.0002). In patients with cardiac tamponade, the plasma BNP levels were low, probably because of impaired ventricular stretching, and the levels significantly increased in response to the primary condition after drainage. This study demonstrates an additional condition that affects the relationship between the plasma BNP levels and cardiac function. If inconsistency is seen in the relationship between the plasma BNP levels and clinical signs of heart failure, the presence of cardiac tamponade should therefore be considered.