Will you estimate BNP or NT-proBNP (N-terminal pro-B-type natriuretic peptide) while on ARNI?
BNP (B-type natriuretic peptide) and NT-proBNP are commonly estimated biomarkers for heart failure. They have importance in diagnosis as well as prognosis . Valsartan/sacubitril is an Angiotensin II Receptor Blocker Neprilysin Inhibitor (ARNI), an important new medication in our therapeutic armamentarium for management of heart failure.
But which one will you estimate if the person is on ARNI and why?
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Excellent discussion by Aditya Mulgaonkar:
The biomarker of choice in HF patient on ARNI would be NT pro-BNP.
Neprilysin breaks down all 3 active natriuretic peptides (ANP, BNP, CNP) but does not affect NT pro-BNP. NT PRO-BNP is resistant to neprilysin inhibition.
In PARADIGM-HF trial, BNP levels actually increased from baseline after 4 weeks of ARNI therapy. But NT PRO-BNP levels decreased from baseline.
This phenomenon is easily explained as BNP degradation was prevented by the ARNI, allowing its levels to rise. Theoretically its level should have fallen with improvement in heart failure but it increased instead, which makes BNP unsuitable for measurement.
As expected, the NT PRO-BNP level fell, indicating improvement in HF. So NT PRO-BNP should be used for monitoring.
Now an emerging concept is that with ARNI, as BNP rises and NT PRO-BNP falls after therapy, the ratio of BNP : NT pro-BNP could be used for assessing response to ARNI.