CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 7, August 2013
288
AFRICA
risk score (rs
=
0.082,
p
=
0.44). Multivariate analysis revealed
that left ventricular ejection fraction and troponin I levels were
independently correlated with NT-pro-BNP levels (
p
=
0.017 and
p
=
0.002, respectively).
14
Renal failure
Renal failure complicates congestive heart failure so often
that many have suggested a ‘cardio–renal’ syndrome, which
influences survival, duration of hospitalisation and re-admission
ratio.
2
A sub-study of PRIDE
15
showed a reduction in the
sensitivity and specificity of NT-pro-BNP in the diagnosis of
heart failure for persons with renal failure, and also showed that
its concentration tends to be more affected by renal dysfunction
than BNP levels.
2
The levels of BNP are known to be significantly
increased for patients on haemodialysis, and they are known to
decrease after dialysis.
2
In another study that involved 72 patients on haemodialysis,
NT-pro-BNP level was not associated with heart failure, but was
dependent on factors associated with an increase in post-load.
16
An association between increased levels of NT-pro-BNP and
chronic renal failure was also demonstrated in patients without
left ventricular dysfunction.
17,18
Diabetes mellitus
In a study on 371 patients with heart failure, 81 of whom had
diabetes, the levels of 10 neurohormones from the plasma
(adrenaline, noradrenaline, dopamine, aldosterone, renin,
endothelin, ANP, NT-pro-ANP, BNP and NT-pro-BNP) were
measured. All patients were also part of the PRIME-II study that
investigated the effects of ibopamine on the causes of mortality
in patients with moderate or severe heart failure.
19
Most of the neurohormones were similar between the two
groups, but patients with diabetes had higher values of BNP
and NT-pro-BNP. The patients were monitored for five years,
and during this time, 195 died, of whom 51 had diabetes. For
patients with diabetes, noradrenaline, ANP, NT-pro-ANP, BNP
and NT-pro-BNP levels were significantly higher than in those
who did not survive. Therefore BNP and NT-pro-BNP proved
the strongest predictors of outcome for both groups of patients.
19
The most likely explanation for the increase in BNP and
NT-pro-BNP levels in these patients with diabetes was the
presence of diastolic dysfunction.
19
Another study showed
normal values of NT-pro-BNP for women with gestational type
2 diabetes mellitus, and lower values for those with insulin-
dependent gestational diabetes.
20
Cirrhotic cardiomyopathy
Cirrhotic cardiomyopathy is an under-diagnosed condition. This
is most likely due to the fact that there is no single diagnostic test
to identify these patients.
21
Numerous recent studies demonstrated that patients with
hepatic cirrhosis had increased plasma concentrations of BNP
and NT-pro-BNP, representing markers of early ventricular
dysfunction. Henriksen
et al
.
22
showed that these markers were
correlated with the severity of hepatic cirrhosis, and with heart
dysfunction. BNP could therefore have prognostic value with
regard to the evolution of cirrhosis. In addition NT-pro-BNP
represents a useful marker to demonstrate the existence of
diastolic dysfunction of the left ventricle caused by a chronic
hepatic disease.
23
A study conducted on 153 patients subjected to a liver
transplant determined their BNP levels post-transplant and on
days 1 and 7. It was observed that a BNP level higher than 391
pg/ml immediately after the liver transplant appeared to be an
early marker for heart dysfunction related to the cirrhosis.
24
Conclusion
In patients with dyspnoea, overlapping or even conflicting
history, physical and radiographic findings often hinder the
differentiation between cardiac and non-cardiac aetiology. The
primary value of BNP and NT-pro-BNP testing in the emergency
department is its diagnostic value in the differential diagnosis of
acute dyspnoea and possible congestive heart failure.
Levels of natriuretic peptides may also assist the emergency
physician in appropriately triaging the patient with congestive
heart failure.
25
Studies have shown that measurements of BNP
or NT-pro-BNP in the emergency department can be used to
establish the diagnosis of congestive heart failure when clinical
presentation is ambiguous or when confounding co-morbidities
are present.
25
After multiple studies, the conclusion was reached that
levels of BNP
<
100 pg/ml and
>
500 pg/ml have a positive and
negative predictive value, respectively, of 90% for the diagnosis
of congestive heart failure for patients presenting with acute
dyspnoea. For values between 100 and 500 pg/ml, the physicians
must consider underlying left ventricular dysfunction, the effects
of renal failure, or right ventricular dysfunction secondary to
chronic pulmonary disease or acute pulmonary embolism.
25
The recommended thresholds of less than 100 pg/ml to
rule out heart failure and more than 500 pg/ml to rule in heart
failure have been estimated to have the following likelihood
ratios (LRs): LR-negative
=
0.13 and LR-positive
=
8.1. These
different cut-off values create an intermediate range of 100–500
pg/ml with an LR-positive of only 1.9 pg/ml. Therefore, an
intermediate BNP result alone cannot be used to rule in or rule
out heart failure.
25
Research done on the POSDRU/6/1.5/S/26 project was co-financed by the
European Social Funds by means of the Sectoral Operational Programme for
the Development of the Human Resources 2007–2013.
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