Screening for cardiac dysfunction in asymptomatic patients by measuring B-type natriuretic peptide levels

Cardiovascular proteomic analysis

Here, we report on our proteomic studies in the field of cardiovascular medicine. Our research has been focused on understanding the role of proteins in cardiovascular disease with a particular focus on epigenetic regulation and biomarker discovery, with the objective of better understanding cardiovascular pathophysiology to lead to the development of new and better diagnostic and therapeutic methods. We have used mass spectrometry for over 5 years as a viable method to investigate protein-protein interactions and post-translational modifications in cellular proteins as well as a method to investigate the role of extra-cellular proteins. Use of mass spectrometry not only as a research tool but also as a potential diagnostic tool is a topic of interest. In addition to these functional proteomics studies, structural proteomic studies are also done with expectations to allow for pinpoint drug design and therapeutic intervention. Collectively, our proteomics studies are focused on understanding the functional role and potential therapeutically exploitable property of proteins in cardiovascular disease from both intra-cellular and extra-cellular aspects with both functional as well as structural proteomics approaches to allow for comprehensive analysis.

Reference intervals and decision limits for B-type natriuretic peptide (BNP) and its precursor (Nt-proBNP) in the elderly

BACKGROUND

Elderly patients have the highest prevalence of heart failure (HF). The aims of the study were to establish a reference interval for B-type natriuretic peptide (BNP) and (Nt-proBNP) in elderly people, and to identify clinically relevant decision limits based on long-term outcome.

METHODS

Plasma concentrations of BNP and Nt-proBNP were measured from two elderly populations: 218 healthy subjects (mean age 73 years, population I), and 474 patients (mean age 73 years, population II) with symptoms associated with HF. Study population II was followed for 6 years with registration of all cardiovascular mortality.

RESULTS

An association between both BNP and Nt-proBNP concentrations and age was found. The upper limit for the reference intervals in the healthy elderly (population I) was: BNP< or =28 pmol/L (< or =97 ng/L), and Nt-proBNP< or =64 pmol/L (< or =540 ng/L). Based on cardiovascular mortality, decision limits for BNP (approximately 50 pmol/L, approximately 170 ng/L) and Nt-proBNP ( approximately 200 pmol/L, approximately 1700 ng/L) (population II) were determined.

CONCLUSIONS

Besides establishing reference intervals for BNP and Nt-proBNP in an elderly population, a higher clinically relevant decision limit for BNP and Nt-proBNP was identified, indicating additive prognostic information of the peptides on top of measurements by echocardiography. Therefore, both reference intervals and decision limits should be included in clinical practice.

Ventricular endocrine and mechanical function following thrombolysis for acute myocardial infarction

OBJECTIVE

The objective of this study was to assess natriuretic peptide release following acute myocardial infarction, and its relationship with ventricular function.

METHODS

A total of 44 patients with acute myocardial infarction were studied; 13 anterior, age (57+/-12 years) and 31 inferior, age (58+/-12 years). Peptide levels and left ventricular function by echocardiography were assessed at admission and on days 7 and 30 after thrombolysis. Healthy volunteers (n=21) served as controls.

RESULTS

Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) levels rose from admission to day 7 (p=0.002). While ANP remained elevated at day 30 in both groups, BNP levels fell in patients with anterior myocardial infarction (p=0.03). Left ventricular fractional shortening was reduced at admission in the two groups (p=0.01) but returned towards normal in 7 days (p=0.001) in inferior myocardial infarction and in 30 days in anterior myocardial infarction (p=0.02). Left ventricular long axis amplitude was universally reduced at admission (p=0.01) and remained abnormal at day 30 (p=0.01) in both groups. At day 7, BNP and ANP levels inversely correlated with long axis amplitude of lateral wall in anterior myocardial infarction; (r=-0.7, p=0.01). BNP correlated inversely with fractional shortening in anterior myocardial infarction (r=-0.7, p=0.01) at day 30.

CONCLUSION

The elevated peptide levels at 7 days post-myocardial infarction correlate with reduced mechanical activity of the adjacent noninfarcted segment. Natriuretic peptides release seem to be related to failure of compensatory hyperdynamic activity of the noninfarcted area rather than directly from the injured myocardial segments.

SPIRONOLACTONE FURTHER REDUCES URINARY ALBUMIN EXCRETION AND PLASMA B-TYPE NATRIURETIC PEPTIDE LEVLES IN HYPERTENSIVE TYPE II DIABETES TREATED WITH ANGIOTENSIN-CONVERTING ENZYME INHIBITOR

1. Over the course of treatment with angiotensin-converting enzyme inhibitor (ACEI), plasma levels of aldosterone have been shown to increase and this increase would blunt the effectiveness of the ACEI (aldosterone escape phenomenon). 2. In the present study, we assessed a potential renal benefit of additional aldosterone blockade with spironolactone in hypertensive diabetic patients treated with ACEI showing the phase of aldosterone escape. 3. The present clinical study was a randomized prospective study to assess difference between the clinical effects of spironolactone and furosemide. Thirty hypertensive type II diabetics (DM2) with a urinary alubumin:creatinine ratio (ACR) above 30 mg/g creatinine (showing albuminuria) and plasma B-type natriuretic peptide (BNP) levels above 100 pg/mL (showing mild heart failure) were treated with an ACEI (imidapril 5 mg/day) for 1 year and then randomly divided into two groups, one group receiving additional spironolactone (25 mg/day) treatment and the other receiving furosemide (20 mg/day) treatment. Blood pressure, ACR and plasma BNP levels were monitored in both groups. 4. Treatment with the ACEI reduced ACR initially but, in 1 year, ACR tended to increase. Additional spironolactone treatment progressively reduced ACR, whereas furosemide treatment did not show any effect. Plasma BNP levels were reduced by ACEI and were further reduced by additional spironolactone treatment, but not furosemide treatment. Blood pressure levels in both groups were comparable. 5. In conclusion, additional therapy with spironolactone in ACEI treatment exerts a renoprotective, as well as cardioprotective, effect in hypertensive diabetes.

Comparative sensitivities between different plasma B-type natriuretic peptide assays in patients with minimally symptomatic heart failure

Plasma B-type natriuretic peptide (BNP) assays have become widely used to diagnose and manage patients with heart failure. However, differences in assay characteristics may have important implications when BNP is used as a screening test for heart failure at a specific cutoff value. We performed a prospective comparison of 2 commercially available assays--one that is a laboratory-based, microparticle enzyme immunoassay (MEIA) that uses EDTA plasma specimens and one that is a point-of-care (POC), single-use fluorescence immunoassay that uses EDTA--anticoagulated whole blood or plasma specimens-in patients with heart failure and healthy controls. Despite the overall concordance between different SNP assays for the diagnosis of heart failure, their sensitivities may differ when compared at the approved diagnostic cutoff value of 100 pg/mL. At this cutoff value, the MEIA on AxSYM demonstrated greater sensitivity than POC Triage BNP assay in minimally symptomatic patients with heart failure. Therefore, for screening purposes, cutoff values for plasma BNP or N-terminal pro-BNP levels should be specific for each assay to optimize test performance. These findings suggest that there is a relationship between the decision statistics used in screening for left ventricular dysfunction and the type of diagnostic assay used.

Detection of cardiac sarcoidosis using cardiac markers and myocardial integrated backscatter

BACKGROUND

It is not known whether cardiac markers and cyclic variations of integrated backscatter can be used to detect cardiac sarcoidosis.

METHODS

We studied 62 patients with sarcoidosis affecting the lung, eyes, skin, or heart (27 patients with cardiac involvement and 35 patients without). The cyclic variation of integrated backscatter and wall thickening was evaluated in the left ventricular anterior septum and posterior wall. Plasma A-type natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) concentrations and serum cardiac troponin T were also determined.

RESULTS

Plasma natriuretic peptide concentrations were higher in the cardiac involvement group (ANP: 15.5 [interquartile range (IQR) 2.5-34.0] vs. 12.0 [10.0-16.5] pg/ml, P=0.25; BNP: 28.6 [5.9-141] vs. 10.1 [4.8-15.4] pg/ml, P=0.049). However, cardiac troponin T concentration was <0.01 ng/ml in all patients. Receiver-operator characteristic (ROC) analysis showed that both ANP and BNP could identify patients with high-degree atrioventricular block, ventricular tachyarrhythmias, or symptomatic heart failure (the areas under the ROC curve were 0.94 and 0.97, respectively). The cardiac involvement group could be distinguished from the noninvolvement group by combining cutoff values for the magnitude of integrated backscatter cyclic variation (5.5 dB) and wall thickening (30%), albeit only for the posterior wall.

CONCLUSION

Both ANP and BNP are useful markers for identifying patients with sarcoidosis and cardiac complication(s). Moreover, evaluation of integrated backscatter cyclic variation combined with wall thickening may be of help in detecting cardiac involvement in the posterior wall.

Myocardial dysfunction in meningococcal septic shock

PURPOSE OF REVIEW

The underlying pathophysiology of sepsis has long been disputed. Systemic vasodilatation is important in the development of shock and, in septic critically ill adults who have been volume resuscitated, the systemic pressure is often low and the cardiac output high. In septic children however, and especially in those with meningococcal septic shock, poor cardiac output as a consequence of depressed myocardial function seems to be important, often being the cause of death in these patients. There is much evidence for disturbance of myocardial performance, yet despite the literature, there is still no consensus on how best to manage this complication of meningococcal disease.

RECENT FINDINGS

Many mediators have been proposed as the cause of the reduced myocardial performance, most recently interleukin-6 has emerged as a possible candidate involved in the pathophysiology of the myocardial dysfunction. Cardiac troponin I has been shown to be a marker of myocardial injury and may be used to monitor left ventricular function. Newer treatments emerging to manage the dysfunction include reports of success with phosphodiesterase inhibitors.

SUMMARY

Accepting that myocardial dysfunction may be an important cause of the shock state in overwhelming meningococcal disease, the approach to management may need to be tailored appropriately. Although presently there is no targeted treatment, it may be that therapy focused on inhibiting or antagonising interleukin-6 will be helpful in the future. Regardless of the importance of myocardial depression, fluid resuscitation remains a cornerstone in the management of severe meningococcal disease.

Brain natriuretic peptide: a potential marker for mortality in septic shock

Brain natriuretic peptide (BNP) is a diagnostic marker for left ventricular dysfunction. Sepsis and septic shock are increasing in incidence and mortality. Myocardial dysfunction frequently accompanies severe sepsis and septic shock. Although previously described as a preterminal event, ventricular dysfunction with reduced ejection fraction and biventricular dilatation is present in most patients with severe sepsis and septic shock. In survivors, this depression in cardiac function is reversible over the course of seven to ten days. Even though some prognostic factors have been identified in patients with sepsis-induced myocardial dysfunction, their measurement often includes costly and cumbersome techniques. Thus, there is a need for an inexpensive, simple, rapid and readily available marker to predict mortality in septic shock. At present, a relationship between BNP with myocardial dysfunction in septic shock has not been evaluated. However, growing evidence supports the hypothesis that BNP could be an early predictor of mortality in septic shock. If proven, the hypothesis would have important clinical and public health implications.

A prospective study in search of an optimal B-natriuretic peptide level to screen patients for cardiac dysfunction

BACKGROUND

Although echocardiography is the gold standard test for suspected left ventricular dysfunction, its cost and availability limits its use as a routine screening tool. The high negative predictive value of B-natriuretic peptide (BNP) in dyspneic patients suggests its possible utility in screening patients prior to echocardiography. Determining an appropriate BNP level below which the need for echocardiography is precluded would be valuable. We hypothesized that a fixed plasma BNP level of 20 pg/mL and simple clinical parameters are an effective pre-echocardiographic screening tool for left ventricular dysfunction.

METHODS

Two hundred and two patients at a Veterans Administration facility with symptoms suggestive of heart disease (male to female ratio 193:9, mean age 65 years) were screened prior to echocardiography. Patients with known cardiac dysfunction were excluded.

RESULTS

BNP levels of > or =20 pg/mL were 79% sensitive and 44% specific in screening for any abnormality of ventricular function. The negative predictive value was 69%. When broken down into categories of dysfunction, the cutoff point of 20 pg/mL had a better negative predictive value for those with systolic dysfunction (96%) or systolic plus diastolic dysfunction (100%) if patients with diastolic dysfunction were excluded. The majority of patients with falsely low BNP levels (<20 pg/mL with positive echocardiographic findings) had mild diastolic dysfunction, with 3 patients exhibiting mild systolic dysfunction.

CONCLUSIONS

BNP may be a useful screening tool for left ventricular dysfunction in patients with history suggestive of heart disease and be used to assist in forming a pretest probability, which in turn could greatly assist in appropriateness of patient referral and in optimization of drug therapy.

Diagnostic accuracy and prognostic relevance of the measurement of cardiac natriuretic peptides: a review

BACKGROUND

The pathophysiologic and clinical relevance of cardiac natriuretic hormone (CNH) assays has been investigated in numerous experimental and clinical studies. Authors have sought to evaluate the diagnostic accuracy and prognostic relevance of the measurement of CNHs according to evidence-based laboratory medicine principles.

METHODS

In June 2003, we ran a computerized literature search on National Library of Medicine using keywords "ANP" and "BNP" and found more than 12 300 and 1200 articles, respectively. A more refined search with keywords "ANP or BNP assay" extracted approximately 7000 and 800 articles, respectively. Only studies specifically designed to evaluate the diagnostic accuracy and prognostic relevance of CNH measurements were selected from this huge mass of articles to be discussed in this review.

CONTENT

Several studies suggested that CNH assays may be clinically useful for the screening and classification of patients with heart failure, as a prognostic marker in cardiovascular disease, in the follow-up of patients with heart failure, and because they may reduce the need for further cardiac investigation. However, it is difficult to compare even the best-designed studies because not only did the authors evaluate different populations, they also used different gold standards.

CONCLUSIONS

CNH assays and conventional diagnostic work-ups provide complementary information for evaluation of the presence and severity of cardiac dysfunction and clinical disease. Several aspects of CNH assays are still to be elucidated, and further work is needed to carefully assess their diagnostic accuracy and prognostic value in cardiac disease.

The confounding effects of age, gender, serum creatinine, and electrolyte concentrations on plasma B-type natriuretic peptide concentrations in critically ill patients

OBJECTIVE

To investigate the confounding effects of age, gender, serum creatinine, and electrolyte concentrations on plasma B-type natriuretic peptide (BNP) concentrations in critically ill patients.

DESIGN

A prospective cross-sectional study.

SETTING

A 20-bed general intensive care unit of a tertiary referral hospital.

PATIENTS

Patients were 121 patients admitted to the intensive care unit over a period of 9 wks.

INTERVENTIONS

Intravenous blood was collected for BNP measurements, and cardiac investigations including echocardiography were carried out for every patient on admission.

MEASUREMENTS AND MAIN RESULTS

The mean BNP concentration was 201 +/- 317 pg/mL (n = 121). Thirty-five patients (28.9%), identified to have cardiac abnormalities, exhibited higher BNP concentrations than those without cardiac abnormalities (518 +/- 394 vs. 60 +/- 98 pg/mL, p <.001). The females exhibited higher concentrations of BNP than males in the noncardiac abnormality group (96 +/- 132 pg/mL, n = 39 vs. 31 +/- 38 pg/mL, n = 47, p =.016). BNP correlated significantly with age (r2 =.19) and creatinine (r2 =.084). The latter correlation became insignificant when patients with cardiac abnormality were excluded. No correlation was found between serum Na+ and K+ concentrations with BNP. Multivariate analyses demonstrated that the presence of cardiac abnormalities accounted for nearly 50% of the BNP variation. Addition of age and gender improved R2 to 60%. The contribution of creatinine was found to be insignificant. There was no association between BNP concentrations and serum Na+ and K+ concentrations. Logistic analysis confirmed that BNP is the strongest predictor for cardiac abnormalities in the critically ill patients.

CONCLUSION

The current study demonstrated that plasma BNP concentrations increased with age and were higher in females than in males. Although the presence of cardiac disease was the most important determinant for BNP variations, age and gender also contributed significantly. The results suggest that age and gender need to be taken into account in the interpretation of BNP concentrations in critically ill patients.

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.

High incidence of elevated B-type natriuretic peptide levels and risk factors for heart failure in an unselected at-risk population (stage A): implications for heart failure screening programs

Only early detection and treatment is likely to stem the current epidemic of heart failure (HF). Several common cardiovascular and metabolic conditions increase the risk of developing symptomatic HF, but its detection by a simple and reliable screening method has proved elusive. HF screening sessions were conducted in September and November 2001. Members of the community with HF risk factors (e.g., hypertension, coronary artery disease, diabetes mellitus, hyperlipidemia) were invited--all specifically without a history of HF. The screening included a history review, health history questionnaire, measurement of blood pressure and pulse, as well as a measurement of B-type natriuretic peptide (BNP) level. A total of 233 individuals attended these two sessions: 108 men and 125 women (mean age, 63 years). Of the 233 subjects screened, the majority (92%) had >or=1 risk factor with an average of 2.8 risk factors for HF. The most common risks included hyperlipidemia (112), hypertension (112), age >65 years (105), cigarette smoking (105), coronary artery disease (60), and diabetes mellitus (54). Many subjects also had symptoms consistent with HF, with most (182, 82%) recording >or=1 symptom. Blood pressure measurements revealed a mean systolic of 139 mm Hg and mean diastolic of 79 mm Hg; on the screening days, 48% and 59% of subjects demonstrated either systolic or diastolic blood pressures above normal, respectively. BNP levels ranged from 0-479 pg/mL with an average of 40 pg/mL. A total of 24 subjects (10.3%) had a BNP level >100 pg/mL, and a total of 32 subjects (13.7%) had a level >80 pg/mL. The follow-up data showed that all 24 subjects saw their physician within 6 months after the screening. By 12 months following the initial screening program, 21 of the 24 subjects with elevated BNP levels (88%) underwent further testing and 18 of the 24 (67%) had changes in their medications. BNP screening identifies subjects at high risk for developing HF. Most subjects at risk have multiple risk factors and abnormal blood pressure. Approximately 10% of this population tested with an abnormal level of BNP, higher than the Food and Drug Administration-assigned cut-point diagnostic for HF. Increased public and physician awareness and information are needed to transform screening opportunities into a strategic approach to improve health care and HF prevention.

[Value of NTproBNP concentration in an out-of-hospital adult population]

INTRODUCTION

The diagnosis of chronic heart failure (CHF) is based on demonstrating the cardiac origin of clinical manifestations. Echocardiography is the method of choice for the detection of left ventricular systolic dysfunction (LVSD). Brain natriuretic peptide (BNP) rises during LVSD.

OBJECTIVES

To analyze the plasma concentration of N-terminal brain natriuretic propeptide (NTproBNP) in a general adult population in relation to different spontaneous circumstances and to study its capacity for identifying patients with LVSD.Methods. A cardiological examination was made and plasma NTproBNP levels were measured in a randomized group of 203 people (49-81 years old) from the Community of Valencia.

RESULTS

The average NTproBNP concentration was 52.2 98.2 pmol/l. NTproBNP levels varied with age, gender and functional stage (NYHA). The highest NTproBNP values were observed in people who had previously suffered from acute pulmonary edema or who had an ejection fraction (EF) of less than 40%. There was also a significant elevation in patients with nocturnal dyspnea, orthopnea, atrial fibrillation, EF < or = 50%, angina, and ankle edema. The best concentration of NTproBNP for differentiating EF < or = 50% was 37.7 pmol/l, with 92% sensitivity and 68% specificity.

CONCLUSIONS

The elevation of NTproBNP concentration indicates the cardiac origin of clinical manifestations and serves to select patients for echocardiographic examination. Low NTproBNP concentrations help to rule out LVSD.

Plasma levels of brain natriuretic peptide: a potential marker for HIV-related cardiomyopathy

One of the most common and life-threatening cardiovascular complications of HIV-infection is severe global left ventricular dysfunction due to primary heart muscle disease. At present, there is no single, cost-effective and reliable method of identifying the highly prevalent HIV-related cardiac dysfunction. Nonetheless, growing evidence supports the hypothesis that brain natriuretic peptide measurement has the potential to detect patients who develop HIV-related cardiomyopathy. If true, this hypothesis would have important clinical and public health implications.

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.