Natriuretic peptides and heart failure
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* Craig S. McLachlan
* Haidong Yu
* Peter Mossop

*   © 2007 Canadian Medical Association or its licensors

We read with interest the recent review by Michael Felker and colleagues,1 in which they suggest that it may be problematic to attempt to use a common plasma reference level for B-type natriuretic peptide as an indicator of the level of functional heart failure because of the degree of interindividual variation. They suggest that B-type natriuretic peptide levels might vary not only according to age and renal function but also according to the stage of heart failure.

We agree with Felker and colleagues that the stage of heart failure influences plasma levels of B-type natriuretic peptide. For example, in the study by Maisel and colleagues cited by the authors,2 the mean levels of B-type natriuretic peptide were as follows: 244 ± 286 pg/mL for patients with New York Heart Association class I heart failure, 389 ± 374 pg/mL for those with class II heart failure, 640 ± 447 pg/mL for those with class III heart failure and 817 ± 435 pg/mL for those with class IV heart failure. In that study, however, the standard deviations were large for each group. It therefore seems inappropriate to focus solely on the diagnostic value of B-type natriuretic peptide levels when assessing heart failure grade, although a high plasma concentration of B-type natriuretic peptide probably indicates class III or class IV heart failure. On the other hand, and more important, a lower plasma concentration of B-type natriuretic peptide may also be associated with class III or class IV heart failure. Therefore, a low plasma level of B-type natriuretic peptide does not rule out a progressive decline in heart function if there has only been a single reading.

## REFERENCES

1.  1. Felker GM, Petersen JW, Mark DB. Natriuretic peptides in the diagnosis and management of heart failure. CMAJ 2006;175(6):611-7.
    
    [Abstract/FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiY21haiI7czo1OiJyZXNpZCI7czo5OiIxNzUvNi82MTEiO3M6NDoiYXRvbSI7czoyMjoiL2NtYWovMTc2LzUvNjU5LjIuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9) 

2.  2. Maisel AS, Krishnaswamy P, Nowak RM, et al. Rapid measurement of B-type natriuretic peptide in the emergency diagnosis of heart failure. N Engl J Med 2002;347(3):161-7.
    
    [CrossRef](http://www.cmaj.ca/lookup/external-ref?access_num=10.1056/NEJMoa020233&link_type=DOI) 
    
    [PubMed](http://www.cmaj.ca/lookup/external-ref?access_num=12124404&link_type=MED&atom=%2Fcmaj%2F176%2F5%2F659.2.atom) 
    
    [Web of Science](http://www.cmaj.ca/lookup/external-ref?access_num=000176869000002&link_type=ISI)