Natriuretic peptides are released from the myocardium in response to fluid overload. 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). Troponin is released in response to myocardial injury. Natriuretic peptides and troponin are raised in patients with HF and could potentially be used to guide treatment however AF can affect the level of these biomarkers by affecting their physiology of their secretion into the blood and also potentially affect their clearance thus affecting the ability of clinicians to interpret their results. Imaging with echocardiography or cardiac MRI could be an alternative method of monitoring. Chronic Heart Failure Monitoring NICE 2018. All rights reserved. Subject to Notice of rights. ISBN: 978-1-4731-3093-7 The aim of this section of the review is to examine the clinical and cost-effectiveness of biomarker measurement or imaging in the management of heart failure in patients with AF. 8.3.2 Review question: What is the clinical and cost effectiveness of biomarker-based monitoring, monitoring with cardiac MRI, and monitoring with repeated echocardiography in people with heart failure who also have atrial fibrillation? For full details see review protocol in Appendix A. Table 88: PICO characteristics of review question Population People diagnosed with heart failure in a community or outpatient setting who also have atrial fibrillation Aged under 75 years Aged 75 and over. 