Failure of plasma brain natriuretic peptide to identify left ventricular systolic dysfunction in the community

Artificial intelligence-enabled electrocardiograms for identification of patients with low ejection fraction: a pragmatic, randomized clinical trial

We have conducted a pragmatic clinical trial aimed to assess whether an electrocardiogram (ECG)-based, artificial intelligence (AI)-powered clinical decision support tool enables early diagnosis of low ejection fraction (EF), a condition that is underdiagnosed but treatable. In this trial ( NCT04000087 ), 120 primary care teams from 45 clinics or hospitals were cluster-randomized to either the intervention arm (access to AI results; 181 clinicians) or the control arm (usual care; 177 clinicians). ECGs were obtained as part of routine care from a total of 22,641 adults (N = 11,573 intervention; N = 11,068 control) without prior heart failure. The primary outcome was a new diagnosis of low EF (≤50%) within 90 days of the ECG. The trial met the prespecified primary endpoint, demonstrating that the intervention increased the diagnosis of low EF in the overall cohort (1.6% in the control arm versus 2.1% in the intervention arm, odds ratio (OR) 1.32 (1.01-1.61), P = 0.007) and among those who were identified as having a high likelihood of low EF (that is, positive AI-ECG, 6% of the overall cohort) (14.5% in the control arm versus 19.5% in the intervention arm, OR 1.43 (1.08-1.91), P = 0.01). In the overall cohort, echocardiogram utilization was similar between the two arms (18.2% control versus 19.2% intervention, P = 0.17); for patients with positive AI-ECGs, more echocardiograms were obtained in the intervention compared to the control arm (38.1% control versus 49.6% intervention, P < 0.001). These results indicate that use of an AI algorithm based on ECGs can enable the early diagnosis of low EF in patients in the setting of routine primary care.

ECG AI-Guided Screening for Low Ejection Fraction (EAGLE): Rationale and design of a pragmatic cluster randomized trial

BACKGROUND

A deep learning algorithm to detect low ejection fraction (EF) using routine 12-lead electrocardiogram (ECG) has recently been developed and validated. The algorithm was incorporated into the electronic health record (EHR) to automatically screen for low EF, encouraging clinicians to obtain a confirmatory transthoracic echocardiogram (TTE) for previously undiagnosed patients, thereby facilitating early diagnosis and treatment.

OBJECTIVES

To prospectively evaluate a novel artificial intelligence (AI) screening tool for detecting low EF in primary care practices.

DESIGN

The EAGLE trial is a pragmatic two-arm cluster randomized trial (NCT04000087) that will randomize >100 clinical teams (i.e., clusters) to either intervention (access to the new AI screening tool) or control (usual care) at 48 primary care practices across Minnesota and Wisconsin. The trial is expected to involve approximately 400 clinicians and 20,000 patients. The primary endpoint is newly discovered EF ≤50%. Eligible patients will include adults who undergo ECG for any reason and have not been previously diagnosed with low EF. Data will be pulled from the EHR, and no contact will be made with patients. A positive deviance qualitative study and a post-implementation survey will be conducted among select clinicians to identify facilitators and barriers to using the new screening report.

SUMMARY

This trial will examine the effectiveness of the AI-enabled ECG for detection of asymptomatic low EF in routine primary care practices and will be among the first to prospectively evaluate the value of AI in real-world practice. Its findings will inform future implementation strategies for the translation of other AI-enabled algorithms.

Natriuretic Peptide testing in primary care

The incidence, as well as the morbidity and mortality associated with heart failure (HF) continue to rise despite advances in diagnostics and therapeutics. A recent advance in the diagnostic and therapeutic approach to HF is the use of natriuretic peptide (NP) testing, including both B-type natriuretic peptide (BNP) and its amino terminal cleavage equivalent (NT-proBNP). NPs may be elevated at an early stage among those with symptoms as well among those without. The optimal approach for applying NP testing in general populations is to select the target population and optimal cut off values carefully. Superior diagnostic performance is observed among those with higher baseline risk (such as hypertensives or diabetics). As well, unlike for acute HF, the cut off value for outpatient testing for BNP is 20-40 pg/mL and for NTproBNP it is 100-150 ng/L. In symptomatic primary care patients, both BNP and NT-proBNP serve as excellent tools for excluding HF based on their excellent negative predictive values and their use may be cost effective. Among those with established HF, it is logical to assume that titration of treatment to achieve lower NPs levels may be advantageous. There are several ongoing trials looking at that prospect.

Value of brain natriuretic peptides in primary care patients with the clinical diagnosis of chronic heart failure

INTRODUCTION

Brain natriuretic peptide (BNP) and N-Terminal pro natriuretic peptide (NT-proBNP) are widely accepted to diagnose congestive heart failure (CHF) in the emergency room. The aim of this study was to evaluate the value of BNP and NT-proBNP to diagnose CHF in primary care.

METHODS

Clinical and Doppler-echocardiographic assessment of patients referred by their general practitioner (GP) with the diagnosis of CHF. Receiver operating curves were used to evaluate the accuracy of BNP and NT-proBNP for echocardiographically confirmed systolic and/or diastolic heart failure.

RESULTS

Three hundred and eighty four patients (mean age of 65) were included. One hundred and ninety three (50%) patients had systolic heart failure and 31 (8%) had isolated diastolic heart failure. Using currently recommended cut-off values of BNP (less than 100 pg/ml) and NT-proBNP (less than 125 pg/ml) for exclusion of CHF, BNP was false negative in 25% and NT-proBNP in 10% of the patients. The area under the curve was better for NT-proBNP than for BNP (0.742 vs. 0.691).

CONCLUSION

In this population with a high prevalence of CHF, BNP and NT-proBNP failed to adequately rule out CHF. GP's should be cautious when using BNP and NT-proBNP in primary care. An echocardiography remains compulsory in unexplained dyspnea.

Serum cardiac troponin T in patients hospitalized with heart failure is associated with left ventricular hypertrophy and systolic dysfunction

BACKGROUND

Cardiac troponin T (cTnT) is a highly sensitive and specific marker of acute myocardial infarction. Serum cTnT is also slightly elevated in patients with severe heart failure and is associated with left ventricular hypertrophy (LVH) in patients treated with haemodialysis. In this study serum cTnT concentrations and echocardiographic findings were investigated in heart failure patients without acute coronary syndrome. cTnT was also compared with other cardiac markers and plasma levels of brain natriuretic peptide (BNP).

METHODS

Twenty-six patients hospitalized with heart failure were included in the study. Echocardiographic measurements and blood sampling were carried out 12-36 h after admission. Serum cTnT (3rd generation assay), cardiac troponin I (cTnI), creatine kinase MB (CKMB) and CK were measured. Plasma BNP was analysed using the Shionoria assay. LVH was defined as left ventricular mass index (LVMI) > 125 g/m for males and > 110 g/m for females. Left ventricular systolic function was estimated from the mitral annulus motion (AV-mean LV).

RESULTS

Median cTnT was 0.012 (< 0.010-0.032) microg/L. Sixty-two percent of the patients (16 of 26) had elevated serum cTnT >or= 0.010 micro/L. cTnT was positively correlated with CKMB (rho = 0.40, p = 0.04) and BNP (rho = 0.43, p = 0.03), but not with cTnI and CK. A negative correlation was found between cTnT and AV-mean LV (rho = -0.58, p = 0.007), and there was a positive correlation between cTnT and LVMI (rho = 0.44, p = 0.03). No other analyte was correlated to LVMI.

CONCLUSIONS

Serum cTnT but not cTnI was associated with left ventricular dysfunction and LVH in patients hospitalized with heart failure. This explains why cTnT tends to be slightly elevated in patients with heart failure without symptoms of acute myocardial ischaemia.

BNP in the community — Still work to be done…

The role of brain natriuretic peptide (BNP) as a screening tool for left ventricular systolic dysfunction (LVSD) in primary care remains unclear. We compared the efficacy of BNP with that of a 12 lead electrocardiogram (ECG) as a screening tool for LVSD in the setting of open access echocardiography and found BNP to be more sensitive in excluding LVSD than an ECG. The use of BNP in screening for LVSD resulted in a saving of 10 pounds per patient.

Cost‐Effective Strategies to Screen for Left Ventricular Systolic Dysfunction in the Community—A Concept

Early detection of heart failure caused by left ventricular systolic dysfunction (LVSD) is important, since early treatment has been shown to retard the progression of heart failure. While traditional echocardiography remains the standard for the detection of LVSD, electrocardiography and serum brain natriuretic peptide have also been shown to predict LVSD. Recently, hand-held echocardiography systems have been shown to have high predictive accuracy for assessment of LVSD. With the availability of the above bedside and relatively less-costly techniques, compared with traditional echocardiography, the major question now is what is the most cost-effective strategy for screening subjects for LVSD. To date, no studies have systematically addressed this issue, but preliminary data are becoming available. This review article discusses the pros and cons of various investigative strategies and likely cost-effectiveness of each strategy to screen for LVSD.

Sleep-disordered breathing in a general heart failure population: relationships to neurohumoral activation and subjective symptoms

The aim of this study was to determine the prevalence of sleep-related breathing disorders (SDB) in a UK general heart failure (HF) population, and assess its impact on neurohumoral markers and symptoms of sleepiness and quality of life. Eighty-four ambulatory patients (72 male, mean (SD) age 68.6 (10) yrs) attending UK HF clinics underwent an overnight recording of respiratory impedance, SaO2 and heart rate using a portable monitor (Nexan). Brain natriuretic peptide (BNP) and urinary catecholamines were measured. Subjective sleepiness and the impairment in quality of life were assessed (Epworth Sleepiness Scale (ESS), SF-36 Health Performance Score). SDB was classified using the Apnoea/Hypopnoea Index (AHI). The prevalence of SDB (AHI > 15 events h(-1)) was 24%, increasing from 15% in mild-to-moderate HF to 39% in severe HF. Patients with SDB had significantly higher levels of BNP and noradrenaline than those without SDB (mean (SD) BNP: 187 (119) versus 73 (98) pg mL(-1), P = 0.02; noradrenaline: 309 (183) versus 225 (148) nmol/24 h, P = 0.05). There was no significant difference in reported sleepiness or in any domain of SF-36, between groups with and without SDB (ESS: 7.8 (4.7) versus 7.5 (3.6), P = 0.87). In summary, in a general HF clinic population, the prevalence of SDB increased with the severity of HF. Patients with SDB had higher activation of a neurohumoral marker and more severe HF. Unlike obstructive sleep apnoea, SDB in HF had little discernible effect on sleepiness or quality of life as measured by standard subjective scales.

The diagnostic accuracy and utility of a B-type natriuretic peptide test in a community population of patients with suspected heart failure

BACKGROUND

National guidelines suggest the use of natriuretic peptides in suspected heart failure but there have been no studies comparing assays in primary care.

AIM

To test and compare the diagnostic accuracy and utility of B-type natriuretic peptide (BNP) and N-terminal B-type natriuretic peptide (NT proBNP) in diagnosing heart failure due to left ventricular systolic dysfunction in patients with suspected heart failure referred by GPs to one-stop diagnostic clinics.

DESIGN OF STUDY

Community cohort, prospective, diagnostic accuracy study.

SETTING

One-stop diagnostic clinics in Darlington Memorial and Bishop Auckland General Hospitals and general practices in South Durham.

SUBJECTS

Two hundred and ninety-seven consecutive patients with symptoms and signs suggestive of heart failure referred from general practice.

METHOD

The study measured sensitivity, specificity, positive and negative predictive values (PPV, NPV), and area under receiver operating characteristic curve for BNP (near patient assay) and NT proBNP (laboratory assay) in diagnosis of heart failure due to left ventricular systolic dysfunction. The NPV of both assays was determined as a potential method of reducing the number of referrals for echocardiography.

RESULTS

One hundred and fourteen of the 297 patients had left ventricular systolic dysfunction (38%). At the manufacturer's recommended cut-off of 100 pg/ml BNP gave a NPV of 82%. BNP performed better at a cut-off of 40 pg/ml with a NPV of 88%. At a cut-off of 150 pg/ml, NT proBNP gave a NPV of 92%. Using cut-offs of 40 pg/ml and 150 pg/ml for BNP and NT pro-BNP, respectively, could have prevented 24% and 25% of referrals to the clinic, respectively.

CONCLUSIONS

In this setting, NT pro-BNP performed marginally better than BNP, and would be easier to use practically in primary care. A satisfactory cut-off has been identified, which needs validating in general practice. NT pro-BNP could be used to select referrals to a heart failure clinic or for echocardiography. This process needs testing in real-life general practice.

The emerging role of echocardiography in the screening of patients at risk of heart failure

A large number of patients without symptoms of heart failure (HF) have asymptomatic left ventricular (LV) dysfunction owing to the compensatory mechanisms acting through the autonomic nervous system and neurohormones. In the setting of screening for prevention, one must identify the subgroup of these patients at high risk for symptomatic HF to establish appropriate therapy. As a first step to identify the subgroup of patients at high risk, clinical screening scores and natriuretic peptide measurements are used. Second, the definite diagnosis of asymptomatic LV dysfunction must be confirmed with echocardiography, occasionally with the help of new technologic developments to establish prompt, appropriate treatment to prevent disease progression. Therefore, the screening role of echocardiography is the early identification of patients with structural cardiopathy who are at risk of developing symptomatic HF and detection of those without LV dysfunction (diabetic and hypertensive) whose condition is prone to advance rapidly to structural cardiopathy or to symptomatic HF.

Can pro-brain natriuretic peptide be used as a noninvasive predictor of elevated left ventricular diastolic pressures in patients with normal systolic function?

OBJECTIVES

This study was sought to investigate whether plasma N-terminal pro-brain natriuretic peptide (proBNP) can help identify patients with an elevated left ventricular end-diastolic pressure (LVEDP) or filling pressures in patients with a normal systolic function.

BACKGROUND

The proBNP is a good predictor of an elevated LVEDP in patients with a systolic dysfunction. However, whether proBNP can predict an elevated LVEDP in patients with a normal systolic function remains to be determined.

METHODS

The LV pressures were measured by fluid-filled catheters in 216 patients (125 men, mean age 60 +/- 10 years) with a normal systolic function (ejection fraction 66% +/- 8%, range 50%-81%) who were undergoing diagnostic cardiac catheterization. The proBNP was sampled at the time of cardiac catheterization and was measured using a quantitative electrochemiluminescence immunoassay.

RESULTS

The log-transformed proBNP levels correlated significantly with the LVEDP (r = 0.33, P = .001) and LV pre-A-wave pressure (pre-A pressure) (r = 0.31, P = .001). An elevated proBNP, defined as >315 pg/mL, predicted an LVEDP > or = 15 mm Hg with a sensitivity of 16% and a specificity of 95% as well as a pre-A pressure > or = 15 mm Hg with a sensitivity of 36% and a specificity of 95%. However, among the 93 patients with an LVEDP > or = 15 mm Hg, 77 (83%) patients had a normal proBNP concentration (< 315 pg/mL).

CONCLUSION

The proBNP level showed weak correlations with the LVEDP and LV pre-A pressure in patients with a normal systolic function. Although high proBNP levels can predict an elevated LV diastolic pressure with high specificity, the sensitivity was quite low. Because the majority of patients with an elevated LVEDP had a normal proBNP, the proBNP level may not be suitable as a screening test for assessing LV filling pressures in the presence of normal systolic function.

What is the normal range for N-terminal pro-brain natriuretic peptide? How well does this normal range screen for cardiovascular disease?

AIMS

To define the N-terminal pro-brain natriuretic peptide (NTpBNP) normal range, assessing its cardiovascular screening characteristics in general population and higher risk subjects.

METHODS AND RESULTS

A total of 2320 subjects (1392 general population and 928 high-risk) > or =45 years old, selected randomly from seven community practices, were invited to undergo clinical assessment and echocardiography and to assess NTpBNP serum levels. Of these, 1205 attended. The NTpBNP normal range was calculated and its cardiovascular screening characteristics were assessed. Age (P<0.0001) and female gender (P<0.0001) independently predicted NTpBNP levels in normal subjects. In the general population, age- and gender-stratified normal NTpBNP levels gave a negative-predictive value (NPV) of 99% in excluding left ventricular systolic dysfunction, atrial fibrillation, and valvular heart disease, and a positive predictive value of 56% in detecting any cardiovascular disease assessed. In high-risk subjects, these values were 98 and 62%, respectively. Ninety-five per cent of subjects with NTpBNP levels over four times the normal had significant cardiovascular disease with the others having renal dysfunction.

CONCLUSION

Normal NTpBNP levels should be stratified by age and gender. Normal NTpBNP levels give high NPV in excluding significant cardiovascular disease. Most subjects with raised NTpBNP levels and almost all subjects with NTpBNP levels over four times the normal have significant cardiovascular disease.

Using BNP to develop a risk score for heart failure in primary care

AIMS

Chronic heart failure is a common condition with high mortality. Accurate diagnosis in primary care is difficult. Elevated B-type natriuretic peptide (BNP) is associated with left ventricular systolic dysfunction and increased mortality. Prognostic scoring systems using BNP may help to stratify risk in primary care patients. The aim of this research was to establish the independent variables which predict mortality in a primary care population-prescribed loop diuretics and to generate and validate a scoring system for heart failure in general practice.

METHODS AND RESULTS

Five hundred and thirty-two patients were followed up for a mean of 6.4 years after attending a research clinic for clinical assessment, electrocardiogram (ECG), echocardiography, and BNP. Multivariate analysis was used to establish independent prognostic variables and to generate a prognostic scoring system. The score generated was [0.50 x BNP+5 x age+50 x (CVA+sex+diabetes+ECG)]. The cut-off scores for risk groups were; 25th percentile, 411; 50th percentile, 475; 75th percentile, 524; Harrell's c=0.75.

CONCLUSION

Developing prognostic scoring systems provides a means of risk stratifying patients without relying on a single cut-off diagnostic value for BNP. Further validation of such scoring systems may improve future management of community heart failure patients.

[Brain natriuretic peptide and heart failure, from bench to bedside]

Diagnosing or managing heart failure may still remain difficult. BNP and NT proBNP are neurohormones specifically secreted by myocytes. They have proved their effectiveness to improve clinician's diagnostic accuracy for diagnosing heart failure. BNP use is now recommended by European Society of Cardiology guidelines but multiplication of publications about BNP and NTProBNP show new possible applications for natriuretic peptides.

Is B-type natriuretic peptide a useful screening test for systolic or diastolic dysfunction in patients with coronary disease? Data from the Heart and Soul Study

BACKGROUND

Whether B-type natriuretic peptide (BNP) levels can be used to screen for ventricular dysfunction in patients at risk of heart failure but without overt symptoms is not known. We examined the characteristics of a BNP test for identifying systolic and diastolic dysfunction in outpatients with stable coronary disease.

METHODS

In a cross-sectional study of 293 outpatients who had stable coronary disease and no history of heart failure, we compared elevations in plasma BNP levels with echocardiography for the diagnosis of systolic dysfunction (ejection fraction <55%) and diastolic dysfunction (diastolic dominant pulmonary vein flow with ejection fraction > or =55%).

RESULTS

A total of 48 patients (16%) had systolic dysfunction, and among the remaining 245 with preserved systolic function, 31 (13%) had diastolic dysfunction. At the standard cutpoint of >100 pg/mL, an elevated BNP level was 38% sensitive (80% specific) for systolic dysfunction and 55% sensitive (85% specific) for diastolic dysfunction. Negative likelihood ratios were 0.8 (95% confidence interval [CI]: 0.6 to 1.0) for systolic dysfunction and 0.5 (95% CI: 0.4 to 0.8) for diastolic dysfunction. Positive likelihood ratios were 1.9 (95% CI: 1.2 to 2.9) for systolic dysfunction and 3.8 (95% CI: 2.4 to 5.9) for diastolic dysfunction. Areas under the receiver operating characteristic curves were 0.59 (95% CI: 0.49 to 0.69) for systolic dysfunction and 0.79 (95% CI: 0.71 to 0.87) for diastolic dysfunction.

CONCLUSION

These data suggest that BNP is not a useful screening test for asymptomatic ventricular dysfunction in patients with stable coronary disease.

Plasma amino-terminal pro-brain natriuretic peptide and accuracy of heart-failure diagnosis in primary care: a randomized, controlled trial

OBJECTIVES

The purpose of this study was to determine the effect of amino-terminal pro-brain natriuretic peptide (N-BNP) on the diagnostic accuracy of heart failure (HF) in primary care.

BACKGROUND

The accurate diagnosis of patients with suspected HF presenting in primary care is difficult. Amino-terminal pro-brain natriuretic peptide is present in high levels in cardiac dysfunction and may improve the diagnostic accuracy of HF in primary care.

METHODS

The Natriuretic Peptides in the Community Study was a prospective, randomized controlled trial of the effect of N-BNP on the accuracy of HF diagnosis. Patients presenting to their general practitioner (GP) with symptoms of dyspnea and/or peripheral edema were included. The GPs formulated an initial diagnosis based on clinical assessment. All patients underwent a full cardiologic assessment that included echocardiography and N-BNP. Each patient was randomized to the BNP group (GP received the N-BNP result) or the control group (GP did not receive the N-BNP result). Patients were then reviewed by their GP, and their diagnosis was reviewed. The primary end point was the accuracy of the GPs' diagnoses compared with the panel standard.

RESULTS

A total of 305 patients were included; mean age was 72 years, 65% were female. Seventy-seven patients met the panel criteria for HF. The diagnostic accuracy improved 21% in the BNP group and 8% in the control group (p = 0.002). The main impact of N-BNP measurement on diagnostic accuracy was the GPs' correctly ruling out HF. The number needed to diagnose by N-BNP measurement was seven patients.

CONCLUSION

This study demonstrates that N-BNP measurement significantly improves the diagnostic accuracy of HF by GPs over and above customary clinical review.

Natriuretic peptide measurement as a screening test for overt and subclinical heart failure

The prevalence of heart failure will increase in a number of industrialized countries as the proportion of elderly within the population increases. Despite recent advances in medical and surgical intervention, the prognosis for this disorder has not improved significantly. To make a major impact on the prognosis for heart failure, it would be important to be able to recognize various forms of heart disease before severe heart failure has developed. Chest X-radiography, ECG and echocardiography may not be adequate screening tools for heart failure in large populations. Natriuretic peptides are secreted from the heart in response to various cardiac abnormalities including ventricular dysfunction, volume overload, hypertrophy, and myocardial ischemia. Circulating levels of natriuretic peptides are elevated in various forms of structural cardiac disease regardless of etiology and the degree of ventricular systolic dysfunction. Natriuretic peptides, specifically B-type natriuretic peptide, are practically stable and can be measured without an extraction procedure. We have reviewed the recent status of plasma natriuretic peptide measurement for identification of patients with congestive heart failure, left ventricular dysfunction, and high risk of heart failure, especially in mass screening settings.

N-terminal proatrial natriuretic peptide in primary care: relation to echocardiographic indices of cardiac function in mild to moderate cardiac disease

AIMS

In patients with chronic heart failure plasma levels of N-terminal proatrial natriuretic peptide (Nt-proANP) correlate to cardiac filling pressures. The aim of the present study was to examine the relation between Nt-proANP plasma levels and echocardiographic indices of cardiac dysfunction in patients recruited from primary care.

METHODS AND RESULTS

After clinical examination by the primary care physician, the patients were referred to one of two centres for echocardiography and blood sampling. In patients with mild to moderate symptoms of heart failure (n=52) and in asymptomatic patients with long-standing hypertension (n=46) or previous myocardial infarction (n=97), peptide levels were most closely related to parameters of left atrial wall stress. Patients who according to echocardiographic predefined criteria had diastolic or systolic dysfunction had two- and three-fold higher Nt-proANP than controls. According to receiver operating curve (ROC) analysis, Nt-proANP measurements were helpful in ruling out left ventricular systolic dysfunction, but not diastolic dysfunction.

CONCLUSION

In patients with mild to moderate cardiac disease, Nt-proANP plasma concentration was related to increased atrial wall stress. Peptide measurement could assist in ruling out the presence of LV systolic dysfunction, but was otherwise of limited value when used for diagnostic subgrouping into echocardiographically determined function categories.

The diagnosis of heart failure in general practice: implications for the UK National Service Framework

BACKGROUND

The UK National Service Framework recommends patients with suspected heart failure undergo echocardiography. Selection of patients for this investigation in primary care is difficult. It is not clear which clinical features best identify patients with left ventricular systolic dysfunction.

AIM

Using echocardiography, to establish the accuracy of primary care diagnosis of left ventricular systolic dysfunction. To investigate the sensitivity, specificity and predictive values of clinical features in the diagnosis of left ventricular systolic dysfunction.

STUDY

A cross-sectional study of 621 patients from a population prescribed loop diuretics in 7 general practices.

METHOD

Clinical diagnoses were extracted from general practice records. Symptoms, clinical signs, ECG features, brain natriuretic peptide levels and echocardiographic findings were studied in a research clinic.

RESULTS

Left ventricular systolic dysfunction (ejection fraction <40%) was present in 50% of 621 patients prescribed loop diuretics in primary care. General practice diagnoses showed high false positive rates. Individual or combinations of clinical features did not accurately predict left ventricular systolic dysfunction.

CONCLUSION

These results suggest the clinical diagnosis of left ventricular systolic dysfunction is inaccurate in this population. General practitioners should have a low threshold for referring patients prescribed loop diuretics for echocardiography. Increased open access echocardiography facilities will be needed.

Retrospective analysis of the cost-effectiveness of using plasma brain natriuretic peptide in screening for left ventricular systolic dysfunction in the general population

OBJECTIVES

We sought to assess the cost-effectiveness of using plasma brain natriuretic peptide (BNP) as a pre-echocardiographic screening test for left ventricular systolic dysfunction (LVSD) in the general population.

BACKGROUND

We hypothesized that plasma BNP and simple clinical parameters would reduce the number of echocardiograms needed and cost when screening for LVSD in the general population.

METHODS

A random sample of 1,257 community subjects (age 25 to 74 years) was examined. Three risk groups were formed: one group with symptomatic ischemic heart disease (IHD); a second group with blood pressure >160/95 mm Hg and/or an abnormal electrocardiogram (high risk); and a group with none of these risk factors (low risk). The BNP assay was adjusted to give a high sensitivity.

RESULTS

Left ventricular systolic dysfunction was prevalent in 0.7% (6/823), 6% (16/269), and 19% (26/140) of low-risk and high-risk subjects and IHD subjects, respectively. Raised BNP concentrations (>8 pg/ml) occurred in 41%, 64%, and 71%. Sensitivities of BNP for detecting LVSD were 83% (5/6), 94% (15/16), and 92% (24/26); and the negative predictive values were 99.8%, 99.0%, and 95.1%. Brain natriuretic peptide was not associated with LVSD in low-risk subjects (p = 0.087), but in IHD subjects (p = 0.015) and high-risk subjects (p = 0.023). Screening high-risk subjects by BNP before echocardiography could have reduced the cost per detected case of LVSD by 26% for the cost ratio of 1/20 (BNP/echocardiogram).

CONCLUSIONS

Subjects at low and high risk of LVSD can be identified by simple clinical parameters, and BNP testing further reduces the number of echocardiograms needed and the costs of screening in subjects at risk <75 years of age in the general population.

Value of plasma B type natriuretic peptide measurement for heart disease screening in a Japanese population

BACKGROUND

Conflict exists regarding the usefulness of measuring plasma B type natriuretic peptide (BNP) concentrations for identifying impaired left ventricular (LV) systolic function during mass screening. Various cardiac abnormalities, regardless of degree of LV dysfunction, are prone to carry a high risk of cardiovascular events.

OBJECTIVE

To examine the validity of plasma BNP measurement for detection of various cardiac abnormalities in a population with a low prevalence of coronary heart disease and LV systolic dysfunction.

DESIGN AND SETTING

Participants in this cross sectional study attended a health screening programme in Iwate, northern Japan. Plasma BNP concentrations were determined in 1098 consecutive subjects (mean age 56 years) by direct radioimmunoassay. All subjects underwent multiphasic health checkups including physical examination, ECG, chest radiography, and transthoracic echocardiography.

RESULTS

Conventional diagnostic methods showed 39 subjects to have a wide range of cardiac abnormalities: lone atrial fibrillation or flutter in 11; previous myocardial infarction in seven; valvar heart disease in seven; hypertensive heart disease in six; cardiomyopathy in six; atrial septal defect in one; and cor pulmonale in one. No subjects had a low LV ejection fraction (< 40%). To assess the utility of plasma BNP measurement for identification of such patients, receiver operating characteristic analysis was performed. The optimal threshold for identification was a BNP concentration of 50 pg/ml with sensitivity of 89.7% and specificity of 95.7%. The area under the receiver operating characteristic curve was 0.970. The positive and negative predictive values at the cutoff level were 44.3% and 99.6%, respectively.

CONCLUSION

Measurement of plasma BNP concentration is a very efficient and cost effective mass screening technique for identifying patients with various cardiac abnormalities regardless of aetiology and degree of LV systolic dysfunction that can potentially develop into obvious heart failure and carry a high risk of a cardiovascular event.

BNP and congestive heart failure

Brain natriuretic peptide (BNP), a peptide hormone secreted chiefly by ventricular myocytes, plays a key role in volume homeostasis. The plasma concentration of BNP is raised in various pathological states, especially heart failure. Many studies suggest that measurement of plasma BNP has clinical utility for excluding a diagnosis of heart failure in patients with dyspnea or fluid retention and for providing prognostic information in those with heart failure or other cardiac disease. It may also be of value in identifying patients after myocardial infarction in whom further assessment of cardiac function is likely to be worthwhile. Preliminary evidence suggests that measuring the plasma concentration of BNP may be useful in fine tuning therapy for heart failure. Artificially raising the circulating levels of BNP shows considerable promise as a treatment for heart failure. With simpler assay methods now available, it is likely that many physicians will measure plasma BNP to aid them in the diagnosis, risk stratification, and monitoring of their patients with heart failure or other cardiac dysfunction.

Incremental importance of peak-exercise plasma levels of endothelin-1 and natriuretic peptides in chronic heart failure

Chronic heart failure (CHF) studies investigating the clinical, hemodynamic, and therapeutic importance of endothelin-1 (ET-1), atrial natriuretic peptide (ANP), and brain natriuretic peptide (BNP) are largely based on resting plasma levels, which may vary with prior exertion and postprandial status. This study investigated the importance of peak-exercise plasma levels of ET-1, ANP, and BNP in the assessment of left ventricular (LV) systolic function. Thirty-six male-patients ages 58 +/- 10 (mean +/- SD ) with NYHA class I-IV CHF due to coronary artery disease or idiopathic dilated cardiomyopathy were enrolled. LV systolic function was assessed by echocardiography and radionuclide ventriculography. Resting and peak cardiopulmonary exercise venous blood sampling and treadmill exercise testing were performed in the fasting state. Resting plasma levels of ET-1, ANP, and BNP were elevated compared with reference laboratory normal values. Exercise induced significant (p < 0.0001) increase in plasma levels of ET-1, ANP, and BNP. On univariate analysis peak-exercise plasma levels of ET-1, ANP, and BNP were more closely related to echocardiographically determined LV end-diastolic diameter and end-systolic diameter than their resting values. Multiple step-wise regression models identified resting and peak-exercise plasma levels of ET-1 and ANP but only the resting BNP as independent predictors of LV dimensions and systolic function. Peak exercise plasma levels of ANP and ET-1 are potentially more reliable and important than their resting levels as markers of LV systolic dysfunction and LV dimensions in patients with heart failure.

Assessment of brain natriuretic peptide in patients with suspected heart failure: comparison with radionuclide ventriculography data

BACKGROUND

The aim of the study was to prospectively evaluate patients with suspected or known heart disease using plasma brain natriuretic peptide (BNP) measurement and radionuclide ventriculography to examine whether left ventricular dysfunction is associated with an abnormal rise of BNP concentration.

METHODS

Patients (n=153) and controls (n=14) underwent radionuclide ventriculography to determine Left ventricular Ejection Fraction (LVEF) and measurement of plasma BNP concentration using a commercial kit.

RESULTS

Plasma BNP concentration in controls was significantly lower than that in patients whatever the stage of the disease, significantly lower than that of patients with normal LVEF (LVEF>55%); than that of patients with altered LVEF (LVEF< or =40%); and than that of patients with moderately reduced LVEF (40%<LVEF< or =5%). Comparisons between groups of patients showed that the more severe the disease, the higher the BNP level. From the ROC curve, a plasma BNP concentration of 52 pg/ml was attached to a 85% sensitivity and 82% specificity in identifying patients with LVEF< or =40%.

CONCLUSIONS

Plasma BNP concentration provides a reliable and sensitive marker of LV systolic dysfunction evaluated by a nuclear medicine technique, and could be a potential screening test to identify patients for additional investigations.