Monitoring Biomarkers in Patients Receiving Neprilysin Inhibitors

Angiotensin Receptor-Neprilysin Inhibitors and the Natriuretic Peptide Axis

PURPOSE OF THE REVIEW

The purpose of this review is to describe the effects of angiotensin receptor neprilysin inhibitor (ARNI) therapy on the natriuretic peptide axis (NPA), with a particular focus on B-type natriuretic peptide (BNP), atrial natriuretic peptide (ANP), and C-type natriuretic peptide (CNP) to better understand the biology behind the improved outcomes in patients with heart failure with reduced ejection fraction (HFrEF).

RECENT FINDINGS

BNP, ANP, and CNP are the three main natriuretic peptides (NP); they share a common structure and ultimately mediate their actions by activating cyclic guanosine monophosphate (cGMP). ARNI therapy results in a decrease of N-terminal pro-BNP (NT-proBNP) and increase of BNP levels respectively. It is been questioned whether these changes may result from unique laboratory assays characteristics rather than actual biological implications. It appears to be that the prognostic accuracy of BNP for cardiovascular outcomes remains independent and comparable to that of NT-proBNP while on ARNI therapy. ANP levels also increase with ARNI therapy, but no consistent change has been described for CNP levels. There is evidence that the changes in BNP and NT-proBNP correlate with improvement in echocardiographic parameters of volume and function. The dual effect of neprilysin inhibition and angiotensin receptor blockade has substantial implications on the natriuretic peptide axis (NPA). The changes seen in BNP and NT-proBNP specifically have shown to correlate with improvement in echocardiographic parameters. Further results exploring the biologic effects of ARNI therapy on other NPs are still pending and likely will provide further insights in the mechanisms behind the improvement in cardiac function and clinical outcomes.

B-Type Natriuretic Peptide During Treatment With Sacubitril/Valsartan: The PARADIGM-HF Trial

BACKGROUND

Natriuretic peptides are substrates of neprilysin; hence, B-type natriuretic peptide (BNP) concentrations rise with neprilysin inhibition. Thus, the clinical validity of measuring BNP in sacubitril/valsartan-treated patients has been questioned, and use of N-terminal pro-B-type natriuretic peptides (NT-proBNP) has been preferred and recommended.

OBJECTIVES

The purpose of this study was to determine the prognostic performance of BNP measurements before and during treatment with sacubitril/valsartan.

METHODS

BNP and NT-proBNP were measured before and after 4 to 6 weeks, 8 to 10 weeks, and 9 months of treatment with sacubitril/valsartan in the PARADIGM-HF (Prospective Comparison of ARNI with ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure) trial. We assessed the association of levels of these natriuretic peptides with the subsequent risk of cardiovascular death or hospitalization for HF.

RESULTS

Median BNP concentration (before treatment: 202 ng/l [Q1 to Q3: 126 to 335 ng/l]) increased to 235 ng/l (Q1 to Q3: 128 to 422 ng/l) after 8 to 10 weeks of treatment. BNP concentrations doubled in 141 (18%) patients and tripled in 49 (6%) patients during the first 8 to 10 weeks of sacubitril/valsartan. In contrast, such striking increases in NT-proBNP following the use of the neprilysin inhibitor were extremely rare. Treatment with sacubitril/valsartan caused a rightward shift in the distribution of BNP when compared with NT-proBNP, but both peptides retained their prognostic accuracy (C-statistics of 63% to 67% for BNP and C-statistics of 64% to 70% for NT-proBNP) with no difference between the 2 biomarkers. Increases in both BNP and NT-proBNP during 8 to 10 weeks of sacubitril/valsartan were associated with worse outcomes (p = 0.003 and p = 0.005, respectively).

CONCLUSIONS

Circulating levels of BNP may increase meaningfully early after initiation of sacubitril/valsartan. In comparison, NT-proBNP is not a substrate of neprilysin inhibition, and thus may lead to less clinical confusion when measured within 8 to 10 weeks of drug initiation. However, during treatment, either biomarker predicts the risk of major adverse outcomes in patients treated with angiotensin receptor-neprilysin inhibitors. (Prospective Comparison of ARNI with ACEI to Determine Impact on Global Mortality and Morbidity in Heart Failure [PARADIGM-HF]; NCT01035255).