Q1. What is the role of NT-proBNP in the diagnosis of heart failure?
Heart failure (HF) is common and the symptoms are fairly nonspecific. So, you can have someone presenting with shortness of breath or fatigue, but there can be a lot of differential diagnoses.
One of the first places it (NT-proBNP) would be useful is in excluding other conditions which cause symptoms of fatigue, shortness of breath, like lung disease, depression or other things. If the NT-proBNP is below 300pg/mL or BNP is below 100pg/mL, it’s a good way of ruling out HF caused by shortness of breath. If it’s above those levels, it is likely to be HF, but there are other things as well. That means it’s a nice way for GPs to be able to triage patients as to who to refer for echocardiography or for whom to get an early referral to a cardiologist, particularly if the level is very high.
So, it’s a nice way of excluding, triaging and arranging your investigations. It means that some patients will not get unnecessary tests, unnecessary referrals and it is also a way of streamlining their care. It really does give diagnostic confidence to the doctor that they think this is HF, and they are happy to be able to manage them initially before referring them to more specialized treatment.
Q2. How does NT-proBNP compare to other heart failure assessment tools?
Clinical judgement is still the most important because heart failure is a clinical syndrome with shortness of breath, fatigue, loss of appetite, inability to do things which you wanted to do with some signs – some basal crepitation in the lungs, peripheral oedema and signs of hypoperfusion of some of the vital organs.
You have got your clinical judgement, you have got your science, and after that, you want to have some tests to be able to confirm your diagnosis and to increase your clinical confidence in diagnosing heart failure. So, the NT-proBNP does add to clinical accuracy and clinical judgement.
Q3. What role does NT-proBNP play in understanding the risk of HF in T2DM patients?
One of the big problems in diabetes is that more than two-thirds of the patients with type 2 diabetes die because of cardiovascular disease, because of MI (myocardial infarction). So, it’s important that we try and identify them earlier.
The other thing is that, if you look at people who have had type 2 diabetes for greater than 5 years, at least two-thirds will have some degree of either systolic dysfunction or diastolic dysfunction or both. So, if someone who had type 2 diabetes for more than 5 years, performing NT-proBNP can help triage patients as to whether they may have some cardiovascular disease or indeed some HF; so that you can go on to investigate them sooner.
The other problem is that in a significant proportion of people with cardiovascular disease, the first symptom is sudden death. And we know that the people with type 2 diabetes have silent myocardial ischemia, so they might be asymptomatic of their ischemia and if we can catch them before they have their myocardial infarction or their sudden death, that would be great, and NT-proBNP may be useful there.
It is also quite useful in picking up these people with heart failure who may be thinking that they are old, or it’s a side effect of their diabetes or other medications or their blood pressure is going up or down, when it’s actually heart failure. So, I think it would be very useful in those people to be able to do the NT-proBNP and pick it out.
