This was on the basis that these patients would already be receiving specialist clinical review and assessment and were not relevant to a diagnostic pathway focussed primarily on patients presenting to primary care with heart failure symptoms. The 2010 CHF guideline CG108 included echocardiography as a second reference standard, the committee discussed the clinical diagnosis of heart failure and agreed that echocardiography alone did not constitute a gold standard for diagnosis and that a definitive diagnosis should be based on the opinion of at least one cardiologist which considered symptoms and objective evidence of cardiac dysfunction (either structural or functional). Due to the lack of evidence regarding the optimal threshold for NT-proBNP in either people with HF and atrial fibrillation or HF and CKD the committee agreed that further research in this area would be beneficial for future updates of this guideline. In addition to this the committee agreed that a large study was needed to Chronic Heart Failure Diagnosing heart failure NICE 2018. All rights reserved. Subject to Notice of rights. ISBN: 978-1-4731-3093-7 provide more certainty with regards to which NT-proBNP threshold (400pg/ml or 125pg/ml) is more clinically and cost effective for the diagnosis of HF in people with suspected HF would also be of benefit for future guideline updates due to the limitations of current diagnostic accuracy studies. The committee agreed that the 400pg/ml and 125pg/ml thresholds would be of most interest as these are the two thresholds used in practice. 400pg/ml is used in the UK, and has previously been used elsewhere until recently. However, the European Society of Cardiology and the American Heart Association has reduced the threshold to 125pg/ml. See section 5.4 of 2010 guideline (Appendix R): BNP2: Natriuretic peptides vs echocardiography. Chronic Heart Failure Diagnosing heart failure NICE 2018. All rights reserved. 