Comparison of the cardiac markers B-type natriuretic peptide and N-terminal pro B-type natriuretic peptide

Atrial Fibrillation, thromboembolic risk, and the potential role of the natriuretic peptides, a focus on BNP and NT-proBNP - A narrative review

Atrial fibrillation (AF) is one of the most commonly encountered arrythmia in clinical practice. AF itself can be driven by genetic predisposition, ectopic electrical activity, and abnormal atrial tissue substrates. Often there is no single etiological mechanism, but rather a combination of factors that feed back to remodel and worsen tissue substrate, "AF begets AF". The clinical consequences of AF can often include emboli, heart failure, and early mortality. The classical AF cardioembolic (CE) concept requires thrombus formation in the left atrial appendage, with subsequent embolization. The temporal dissociation between AF occurrence and CE events has thrown doubt on AF as the driver of this mechanism. Instead, there has been a resurgence of the "atrial cardiomyopathy" (ACM) concept. An ACM is proposed as a potential mechanism of embolic disease through promotion of prothrombotic mechanisms, with AF instead reflecting atrial disease severity. Regardless, AF has been implicated in 25% to 30% of cryptogenic strokes. Natriuretic peptide(NP)s have been shown to be elevated in AF, with higher levels of both NT-proBNP and BNP being predictive of incidental AF. NPs potentially reflect the atrial environment and could be used to identify an underlying ACM. Therefore, this narrative review examines this evidence and mechanisms that may underpin the role of NPs in identifying atrial dysfunction, with focus on both, BNP and NTproBNP. We explore their potential role in the prediction and screening for both, ACM and AF. Moreover, we compare both NPs directly to ascertain a superior biomarker.

B-type natriuretic peptide over N-terminal pro-brain natriuretic peptide to predict incident atrial fibrillation after cryptogenic stroke

BACKGROUND AND PURPOSE

B-type natriuretic peptide (BNP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) are well-known surrogates of atrial fibrillation (AF) detection but studies usually present data on either BNP or NT-proBNP. The aim was to determine and directly compare the validity of the two biomarkers as a tool to predict AF and guide prolonged cardiac monitoring in cryptogenic stroke patients.

METHODS

Non-lacunar acute ischaemic stroke (<72 h) patients over 55 years of age with cryptogenic stroke after standard evaluation were included in the Crypto-AF study and blood was collected. BNP and NT-proBNP levels were determined by automated immunoassays. AF was assessed by 28 days' monitoring. Highest (optimizing specificity) and lowest (optimizing sensitivity) quartiles were used as biomarker cut-offs to build predictive models adjusted by sex and age. The integrated discrimination improvement index (IDI) and DeLong test were used to compare the performance of the two biomarkers.

RESULTS

From 320 patients evaluated, 218 were included in the analysis. AF was detected in 50 patients (22.9%). NT-proBNP (P < 0.001) and BNP (P < 0.001) levels were higher in subjects with AF and their levels correlated (r = 0.495, P < 0.001). BNP showed an increased area under the curve (0.720 vs. 0.669; P = 0.0218) and a better predictive capacity (IDI = 3.63%, 95% confidence interval 1.36%-5.91%) compared to NT-proBNP. BNP performed better than NT-proBNP in a specific model (IDI = 3.7%, 95% confidence interval 0.87%-6.5%), whilst both biomarkers performed similarly in the case of a sensitive model.

CONCLUSIONS

Both BNP and NT-proBNP were increased in cryptogenic stroke patients with AF detection. Interestingly, BNP outperforms NT-proBNP, especially in terms of specificity.

Diagnostic value of NT-proBNP in identifying impaired coronary flow reserve in asymptomatic moderate or severe aortic stenosis

AIM

NT-proBNP has been shown to be a reliable biochemical marker for left ventricular wall stress. The relationship between NT-proBNP and coronary flow reserve (CFR) was evaluated in patients with significant asymptomatic aortic stenosis (AS).

METHODS

A total of 74 patients with moderate or severe AS, mean age 66.68 ± 10.02 years (56.75% males), were enrolled in this prospective study. All patients underwent coronary angiography and had no obstructive coronary disease (defined as having no stenosis >50% in diameter). They had all undergone standard transthoracic Doppler-echo study and adenosine stress transthoracic-echo for CFR measurement and laboratory analysis for NT-proBNP measurement.

RESULTS

The median NT-proBNP value was significantly increased (417.0 pg/ml; interquartile range [IQR]: 176.8-962.2 pg/ml). NT-proBNP was significantly higher in the group with CFR ≤2.5 (median: 549.0 pg/ml; IQR: 311.5-1131.0 pg/ml; as opposed to median: 291.5 pg/ml; IQR: 123.0-636.2 pg/ml; W = 452; p = 0.012). NT-proBNP showed significant negative correlation with CFR (ρ = -0.377, p = 0.001). There was also significant correlation between NT-proBNP and E/E´, S´ and aortic valve resistance. The NT-proBNP value of 334.00 pg/ml was determined as the best cut-off value for the diagnosis of CFR ≤2.5 (area under the curve: 0.67; 95%CI: 0.54-0.79; p < 0.01) and the sensitivity and specificity were 74 and 64%, respectively.

CONCLUSION

Elevated NT-proBNP can indicate patients with impaired CFR in asymptomatic moderate or severe AS patients with preserved ejection fraction and nonobstructive coronary arteries.

The natriuretic peptides as biomarkers for adults with congenital heart disease

Thanks to improved treatment of congenital heart disease early in life, many such patients reach adulthood. Adults with congenital heart disease are an increasing population, which will continue to grow in the future. The clinical state of these patients is affected by their complex heart diseases, as well as the consequence of past corrective or palliative interventions. The natriuretic peptides are important markers for the presence, severity and prognosis of heart disease. The majority of the current knowledge is on patients with acquired heart disease. This article reviews the present knowledge regarding the role of the natriuretic peptides in adults with various forms of congenital heart disease.

Equal performance of novel N-terminal proBNP (Cardiac proBNP®) and established BNP (Triage BNP®) point-of-care tests

Background: Recently, a novel point-of-care test (POCT) for N-terminal proBNP (NTproBNP) has been introduced (Cardiac proBNP®, Roche). Aim: The aim was to compare the novel POCT for NTproBNP with the established POCT for BNP. Methods: NTproBNP and BNP were assessed in 222 individuals with chronic heart failure (n = 151) or controls (n = 71) with both POCTs. Results: NTproBNP and BNP were closely correlated upon regression analysis (r = 0.93; p < 0.01). NTproBNP and BNP were both correlated with ejection fraction and New York Heart Association stage. Receiver operating characteristic analysis yielded satisfying and equivalent predictive values for the detection of left ventricular dysfunction (ejection fraction <40%; NTproBNP: area under the curve 0.97; BNP: area under the curve 0.96; p > 0.05) and presence of New York Heart Association stage >2 (area under the curve 0.92 vs 0.91 for NT-proBNP and BNP, respectively; p > 0.05). Conclusion: The NTproBNP POCT allows biochemical detection of heart failure with satisfactory predictive values, is equivalent to the BNP POCT and will improve near-patient testing.

Prognostic value of combining echocardiography and natriuretic peptide levels in patients with heart failure

Heart failure (HF) is still a global public health issue, despite the enormous progress made in its diagnosis and treatment. More often than not, acute or chronic decompensated HF leads to hospitalization and presents a dismal prognosis. Evidently, clinical symptoms alone are not reliable enough guidance for the HF treatment; therefore, parameters able to identify adverse prognoses are valuable in tailoring treatment regimens for individual patients. Echocardiography and natriuretic peptides (NPs) have demonstrated their capacities in giving independent diagnostic and prognostic information regarding patients with HF. Although abnormalities either of an echocardiographic index of left ventricular function or of an NP denote an increased risk of mortality or HF, the highest risk comes from abnormalities of both left ventricular function and NP levels. In this review, we survey the most recent publications exploring the utility of NP levels and echocardiographic indices integration, claimed to offer powerful incremental prognostication in patients with established HF.

Biochemical markers in acute coronary syndrome

Owing to their higher risk for cardiac death or ischemic complications, patients with acute coronary syndrome (ACS) must be identified from other causes of chest pain. Patients with acute coronary syndrome are divided into categories based on their electrocardiogram; those with new ST-segment elevation and those who present with ST-segment depression. The subgroups of patients with ST-segment elevation are candidates for immediate reperfusion, while fibrinolysis appears harmful for those with non-ST elevation myocardial infarction. There is increasing evidence to encourage appropriate risk stratification before deciding on a management strategy (invasive or conservative) for each patient. The TIMI, GRACE or PURSUIT risk models are recommended as useful for decisions regarding therapeutic options. Cardiac biomarkers are useful additions to these clinical tools to correctly risk stratify ACS patients. Cardiac troponin is the biomarker of choice to detect myocardial necrosis and is central to the universal definition of myocardial infarction. The introduction of troponin assays with a lower limit of detection will allow for earlier diagnosis of patients who present with chest pain. Analytical and clinical validations of these new assays are currently in progress. The question is whether the lower detection limit of the troponin assays will be able to indicate myocardial ischemia in the absence of myocardial necrosis. Previous to the development of ultrasensitive cardiac troponin assays free fatty acids unbound to albumin and ischemia modified albumin were proposed as biochemical markers of ischemia. Advances in our knowledge of the pathogenesis of acute coronary thrombosis have stimulated the development of new biomarkers. Markers of left ventricular performance (N-terminal pro-brain natriuretic peptide) and inflammation (e.g. C-reactive protein) are generally recognized as risk indicators. Studies suggest that using a number of biomarkers clinicians can risk stratify patients over a broad range of short and long term cardiac events. Nevertheless, it is still under debate as to which biomarker combination is best preferred for risk prediction. This review will focus on recent practice guidelines for the management of patients with ACS as well as current advances in cardiac biomarkers, their integration into clinical care and their diagnostic, prognostic and therapeutic utility.

Predictive value of predischarge spectral tissue doppler echocardiography and n-terminal pro-B-type natriuretic peptide in patients hospitalized with acute heart failure

BACKGROUND

Admission for an acute heart failure (HF) confers an extremely poor prognosis. We aimed at finding out whether simultaneous assessment of multiple plasma-based biomarkers and Doppler echocardiography could provide complementary information and thus enable clinicians to stratify risk more effectively among patients hospitalized with acute HF; hence, untoward events after discharge avoided.

METHODS

A comprehensive echocardiographic study and measurements of cardiac troponin I (cTnI), N-terminal pro-B-type natriuretic protein (NT-proBNP), and high-sensitivity C-reactive protein (hsCRP) were conducted in 87 patients with symptomatic de novo acute HF or decompensation of chronic HF. Major adverse cardiac events (MACE) regarding cardiac death or hospitalization with worsening HF during a median follow-up period of 191 days were determined.

RESULTS

According to the univariate analysis, echocardiographic variables left atrial volume, left atrial volume index, pulmonary artery systolic pressure, E/E' ratio, and the concentrations of NT-proBNP were significantly related to clinical outcomes (all P-values < 0.05). Cox proportional hazard analysis identified two independent prognostic predictors of MACE: E/E' ratio and NT-proBNP. Moreover, the combining of plasma level of NT-proBNP with E/E' ratio provided independent and additional prognostic value in identifying high-risk acute HF patients.

CONCLUSIONS

These findings reinforce the necessity of combining the heart hemodynamic variable E/E' ratio and plasma-based neurohormonal biomarker NT-proBNP when clinicians attempt to define the individual risk of patients hospitalized with acute HF.