This was assessed as directly applicable with potentially serious limitations. 5.2 BNP and NT-proBNP in diagnosing heart failure in people with atrial fibrillation 5.2.1 Review question: In people with suspected heart failure who also have atrial fibrillation, what thresholds of N-terminus 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. Table 20: Characteristics of review question Population People with atrial fibrillation and suspected heart failure in a community or outpatient setting. Target condition Heart failure Index test(s) NT-proBNP BNP Reference standard(s) A clinical diagnosis based on the opinion of at least one cardiologist, considering symptoms (potentially with some signs) and objective evidence of cardiac dysfunction (either structural or functional). Statistical measures Diagnostic accuracy of BNP and NT-proBNP: 2x2 tables Specificity Sensitivity PPV/NPV ROC curve or Area under Curve Chronic Heart Failure Diagnosing heart failure Study design Single gate studies (cohort/cross-sectional) 5.2.2 Review question: In people with suspected heart failure who also have atrial fibrillation, what is the clinical and cost effectiveness of N-terminus pro-B-type natriuretic peptide (NT-proBNP) compared to B-type natriuretic peptide (BNP), when each is followed by the appropriate patient pathway, in order to improve patient outcomes? For full details see review protocol in Appendix A. Table 21: PICO characteristics of review question Population People with atrial fibrillation and suspected heart failure in a community or outpatient setting. Index diagnostic test + treatment NT-proBNP assay (at any reported threshold) Treatment/next step in pathway: Echocardiography Comparator index diagnostic tests + treatment BNP assay (at any reported threshold) Treatment/next step in pathway: Echocardiography Outcomes Efficacy outcomes: All-cause mortality Quality of life Unplanned hospitalisation Process outcomes: Number of people receiving echocardiography, i.e.