The two main natriuretic peptides used in clinical practice are amino-terminal pro-B-type natriuretic peptide (NT-proBNP) and B-type natriuretic peptide (BNP). The levels of natriuretic peptides correlate with prognosis in patients with heart failure and they may also be useful in patients with some other cardiovascular morbidities. The measurement of natriuretic peptides is recommended for the diagnosis of HF in previous NICE guidance. However, further evidence on the diagnostic efficiency of natriuretic peptides for heart failure in community settings has accumulated since that review, and the underlying prevalences of heart failure with reduced ejection fraction (HFREF) and with preserved ejection fraction (HFREF) are changing. The suggestion has been made that previous diagnostic threshold defined by natriuretic peptide levels may need to be revised. This question reviewed whether the diagnostic process for heart failure by the use of the appropriate combination of clinical signs, echocardiographic imaging and natriuretic peptide levels ought to be changed. Please note that natriuretic peptide levels have been reported in pg/ml throughout this review. However, the recommendations made have been converted to ng/L as this is more commonly recognised in practice (1pg/ml = 1ng/L). 5.1.2 Review question: In people with suspected heart failure, what thresholds of pro-B-type natriuretic peptide (NT-proBNP) and B-type natriuretic peptide (BNP) are most accurate in identifying heart failure (as indicated by the reference standard)? For full details see review protocol in appendix A. Chronic Heart Failure Diagnosing heart failure NICE 2018. All rights reserved. Subject to Notice of rights. ISBN: 978-1-4731-3093-7 Table 9: Characteristics of review question Population People with suspected heart failure in a community or outpatient setting. 