Refer people with suspected heart failure and an NT-proBNP level between 400 and 2,000 ng/litre (47 to 236 pmol/litre) to have specialist assessment and transthoracic echocardiography within 6 weeks. [2018] 5. Be aware that: an NT-proBNP level less than 400 ng/litre (47 pmol/litre) in an untreated person makes a diagnosis of heart failure less likely the level of serum natriuretic peptide does not differentiate between heart failure with reduced ejection fraction and heart failure with preserved ejection fraction. [2018] 6. Review alternative causes for symptoms of heart failure in people with NT- proBNP levels below 400 ng/litre. If there is still concern that the symptoms might be related to heart failure, discuss with a physician with subspeciality training in heart failure. [2018] 7. Be aware that: obesity, African or African-Caribbean family origin, or treatment with diuretics, angiotensin-converting enzyme(ACE) inhibitors , beta- blockers, angiotensin II receptor blockers (ARBs) or mineralcorticoid receptor antagonist (MRAs) can reduce levels of serum natriuretic peptides. high levels of serum natriuretic peptides can have causes other than heart failure (for example, age over 70 years, left ventricular hypertrophy, ischaemia, tachycardia, right ventricular overload, hypoxaemia [including pulmonary embolism], renal dysfunction ], sepsis, chronic obstructive pulmonary disease, diabetes, or cirrhosis of the liver). [2010, 8. Perform transthoracic echocardiography to exclude important valve disease, assess the systolic (and diastolic) function of the (left) ventricle, and detect intracardiac shunts. [2003, amended 2018] 9. Transthoracic echocardiography should be performed on high-resolution equipment, by experienced operators trained to the relevant professional Chronic Heart Failure Guideline summary NICE 2018. All rights reserved. Subject to Notice of rights. ISBN: 978-1-4731-3093-7 standards. Need and demand for these studies should not compromise 10. Ensure that those reporting echocardiography are experienced in doing so. 11. 