the NICE clinical guideline on CHF the use of BNP as a diagnostic tool for heart failure (1,2)
refer patients with suspected heart failure and previous myocardial infarction (MI) urgently, to have transthoracic Doppler 2D echocardiography and specialist assessment within 2 weeks (1)
refer people with suspected heart failure and an NT-proBNP level above 2,000 ng/litre (236 pmol/litre) urgently, to have specialist assessment and transthoracic echocardiography within 2 weeks - because very high levels of NT-proBNP carry a poor prognosis
refer people with suspected heart failure and an NT-proBNP level between 400 and 2,000 ng/litre (47 to 236 pmol/litre) to have specialist assessment and transthoracic echocardiography within 6 weeks
review alternative causes for symptoms of heart failure in people with NTproBNP levels below 400 ng/litre. If there is still concern that the symptoms might be related to heart failure, discuss with a physician with subspeciality training in heart failure
perform transthoracic echocardiography to exclude important valve disease, assess the systolic (and diastolic) function of the (left) ventricle, and detect intracardiac shunts
if a poor image is produced by transthoracic echocardiography
consider alternative methods of imaging the heart (for example, radionuclide angiography [multigated acquisition scanning], cardiac MRI or transoesophageal echocardiography)
note that:
obesity, African or African-Caribbean family origin, or treatment with diuretics, angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, angiotensin II receptor blockers (ARBs) or mineralocorticoid receptor antagonists (MRAs) can reduce levels of serum natriuretic peptides
high levels of serum natriuretic peptides can have causes other than heart failure (for example, age over 70 years, left ventricular hypertrophy, ischaemia, tachycardia, right ventricular overload, hypoxaemia [including pulmonary embolism], renal dysfunction [eGFR less than 60 ml/minute/1.73m2], sepsis, chronic obstructive pulmonary disease, diabetes, or cirrhosis of the liver)
the level of serum natriuretic peptide does not differentiate between heart failure due to left ventricular systolic dysfunction and heart failure with preserved left ventricular ejection fraction
Notes:
in the emergency department patients with dyspnoea, BNP and amino terminal proBNP concentrations had similar diagnostic accuracy for detecting patients with congestive heart failure (3,4)
BNP and proBNP and cardiovascular risk
higher concentrations of BNP or proBNP, are consistently associated with increased risk of death and cardiovascular events (5)
proBNP concentrations of >= 100 ng/l increased risk of all-cause mortality in patients with or without stable coronary artery disease (6)
there is also evidence that pro-BNP is a marker of long-term mortality in patients with stable coronary disease and provides prognostic information above and beyond that provided by conventional cardiovascular risk factors and the degree of left ventricular systolic dysfunction (7)
BNP and cardiac toponin in healthy older adults (13)
a study investigated the prognostic value of detectable cardiac troponin T (TnT) and elevated N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels in a population of community-dwelling older adults
revealed that apparently healthy adults with detectable TnT or elevated NT-proBNP levels are at increased risk of death
those with both TnT and NT-proBNP elevations are at even higher risk, and the increased risk persists for years
proBNP and cardiovascular risk in type 2 Diabetes (14)
NT-proBNP was a biomarker with a discriminatory ability to predict both death and CV events as accurately as a multivariable risk model in T2DM patients with CVD and/or CKD comorbidity. NT-proBNP significantly improved the risk stratification of high-risk T2DM patients when added to the multivariable risk prediction model
BNP measurement was superior to two-dimensional echocardiographic determination of EF in identifying CHF, regardless of the threshold value, in patients with acute dyspnoea (8)
in patients with atrial fibrillation (AF)
the presence of AF is associated with higher circulating BNP levels, suggesting that a higher diagnostic threshold should be used in patients with AF 9)
patients with both a completely normal ECG and normal BNP are unlikely to have heart failure (10)
BNP and management of heart failure (11):
low concentrations of BNP make heart failure unlikely
a low concentration (< 100pg/ml) makes heart failure unlikely
high levels of BNP in heart failure predict a poor prognosis
plasma BNP appears to be the most useful single predictor of prognosis. A very high level on optimal drug treatment (above 500 pg/ml) suggests a poor prognosis, and a low level (below 100pg/ml) suggests the patient will do well
driving down BNP levels by aggressive treatment improves the clinical outcome
treatment with a diuretic, ACE inhibitor or angiotensin receptor blocker (ARB) reduces the concentration, and beta-blockers may initially increase but then decrease the blood concentration. Reduced excretion of BNP in serious kidney dysfunction (creatinine above 200 ìmol/l) can contribute to increased plasma BNP levels
patients with heart failure do better if the doctor is aware of the plasma BNP concentration and tries to drive it down to a low level (<100 pg/ml) by more aggressive use of beta-blockers and ACE inhibitors or ARBs
BNP is not recommended for screening for cardiac dysfunction in the general population
NICE state that (1):
consider measuring NT-proBNP (N-terminal pro-B-type natriuretic peptide) as part of a treatment optimisation protocol only in a specialist care setting for people aged under 75 who have heart failure with reduced ejection fraction and an eGFR above 60 ml/min/1.73m2
obesity and natiuretic peptides
main confounder in the interpretation of natriuretic peptides is the concurrent presence of obesity, which is associated with lower BNP/NT-proBNP levels than expected from heart failure severity (14)
(13) Malachias MVB, Jhund PS, Claggett BL, et al.NT-proBNP by Itself Predicts Death and Cardiovascular Events in High-Risk Patients With Type 2 Diabetes Mellitus. J Am Heart Assoc. 2020;9:e017462. DOI: 10.1161/JAHA.120.017462
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