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Amino-terminal Pro-B-type Natriuretic Peptide Testing – Past, Present and Future Applications
Figure 1: Suggested Algorithm for NT-proBNP-based Management of Patients Initially Seen in Office and
Emergency Department Settings
Patients presenting with symptoms of dyspnoea
Outpatient/office/clinic setting Acute setting, such as ED
History and clinical exam, serum NT-proBNP levels
History and clinical exam, EKG, chest X-ray,
serum NT-proBNP levels
NT-proBNP levels >125ng/l for those <75 years of age
History of prior HF No history of prior HF
and 300–450ng/l for those >75 years of age*
Positive Negative
Δ >25% from ‘dry’
NT-proBNP <300ng/l
NT-proBNP grey zone NT-proBNP positive***
NT-proBNP levels**
Heart failure more Proceed with work-up HF unlikely: work-up for
likely: proceed with for non-HF-related
Acute on chronic HF
non-HF-related causes
HF possible: know
HF likely
cardiovascular work-up causes for dyspnoea for dyspnoea
differential diagnosis
HF = heart failure; NT-proBNP = amino-terminal pro-B-type natriuretic peptide. *references 47–52; **reference 67; ***age-adjusted cut-off points of NT-proBNP levels of 450/900/1,800ng/l
for ages <50, 50–75 and >75, respectively.
evaluating these patients is to ascertain their ‘dry’ NT-proBNP level (the interest. Among patients admitted with acute HF, those whose NT-
concentration of NT-proBNP when these patients are in their proBNP levels were >4,647ng/l in the setting of impaired renal function
compensated HF state); NT-proBNP levels that are 25% different from had the worst prognosis compared with patients with median levels
a dry value strongly suggest acute on chronic HF.
67
<4,647ng/l or those with reasonable renal function.
40
These important
findings suggest that renal dysfunction does not impair the ability of NT-
NT-proBNP as a Prognostic Marker in Heart Failure and proBNP to prognosticate, and indicates the potential importance of NT-
Its Potential Value for Management proBNP to define the cardiac portion of the cardio–renal syndrome.
Acute Heart Failure Given the value of NT-proBNP for prognostication, it is only logical to
Several studies indicate that in those with HF, NT-proBNP is a powerful expect a potential for this marker to assist in the management of
tool for prognostication by itself or considered with other variables patients with HF. Indeed, NT-proBNP concentrations are affected by
such as creatinine, haemoglobin or other cardiac biomarkers such as variable physiological changes that happen during acute
troponin, galectin-3 (released by activated macrophages in the context decompensated HF states, and tend to parallel the process of
of HF) or ST2 (an interleukin receptor family member also secreted by recompensation of HF. For example, Knebel et al.
76
found poor
myocytes in response to stretch and a participant in myocardial correlation between single haemodynamic parameters and NT-proBNP
remodelling in HF).
40,42,44,68–75
levels; however, significant decreases in NT-proBNP were found to be
associated with significant responses in pulmonary capillary wedge
In the ICON study,
54
an NT-proBNP of 5,180ng/l was useful for short- pressure during HF therapy. Similarly, Bayes-Genis et al.
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term (76-day) mortality prediction, with a negative predictive value of demonstrated smaller changes (<15%) in NT-proBNP levels over a
96%. In the PRIDE study,
70
examining a relatively longer-term (one-year) seven-day period during acute hospital admission among those who
time horizon, an NT-proBNP cut-point of approximately 1,000ng/l was suffered complications compared with those who survived (who
associated with increased mortality. In addition, the NT-proBNP levels showed a decrease of 50%). Di Somma and colleagues
78
also found a
were able to predict mortality risk not only in acute HF, but also in 58% reduction in NT-proBNP levels over a successful seven-day
dyspnoea without the diagnosis of HF. As complex and dynamic hospital admission for acute decompensated HF.
physiological changes occur in renal function during the management of
patients with HF (so-called ‘cardio–renal’ syndrome), the interpretation More definitive data supporting the measurement of NT-proBNP levels
of NT-proBNP levels in the context of renal failure is of particular to monitor those with acutely destabilised HF came from Bettencourt
ASIA-PACIFIC CARDIOLOGY 71
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