Plasma levels of B-type natriuretic peptide in children and adolescents with aortic valve stenosis

Andreas Max Ernst Koch

University Hospital for Children
and Adolescents
Pediatric Cardiology
Loschgestr. 15
Erlangen
Bavaria 91054
Germany
Tel: 4991318533763
Fax: 4991318535987
E-mail address:
andreas.koch{at}kinder.imed.uni-erlangen.de

We read with interest the recent article of Weber et al.,1 which investigated the relation of N-terminal (NT) pro-B-type natriuretic peptide (BNP) to progression of aortic valve disease. According to their results on a large cohort, the authors considered NT-proBNP as a suitable biomarker for the evaluation and monitoring of patients with aortic valve disease. On the basis of our own experience in paediatric patients, we would like to add a note of caution regarding the diagnostic accuracy of natriuretic peptides in aortic stenosis.

In the last 4 years, we have measured BNP in almost 200 healthy children and more than 400 patients with congenital heart disease using the Triage BNP test (Biosite Inc., San Diego, California, USA).2 Within these examinations, we analysed 25 infants, children, and adolescents (aged 6 weeks to 27 years, median age 9.9 years, 18 males, and seven females) with aortic valve stenosis, with or without mild to moderate aortic insufficiency, but without additional congenital heart disease.3 In 22/25 patients, BNP plasma level was normal according to age- and sex-matched controls (between 5 and 21 pg/mL), despite an invasive pressure gradient of up to 105 mmHg, a left ventricular systolic pressure of up to 220 mmHg, and a markedly increased left ventricular hypertrophy in several patients. Plasma BNP was slightly increased when compared with healthy controls in 2/25 patients (22 and 40 pg/mL, 14.5- and 13.8-year-old boys, peak-to-peak gradient 90 and 65 mmHg, respectively). Only in one case, we found a markedly increased plasma BNP level of 195 pg/mL (age- and sex-matched controls: 8.5±7.5 pg/mL). This 7-week-old girl had aortic valve stenosis with a systolic invasive pressure gradient of 40 mmHg, without left ventricular hypertrophy, but with an increased left ventricular diastolic and systolic dimension (shortening fraction 30%).

We could not find any correlation between plasma BNP level and invasive peak-to-peak gradient or maximal aortic velocity assessed by continuous-wave Doppler echocardiography. To our experience, in children and adolescence, it would be harmful to wait for elevated BNP levels before initiating interventional or surgical treatment.

We estimate that elevated plasma levels of BNP do not correlate to the severity of aortic valve obstruction but reflect the occurrence and the degree of left ventricular dysfunction. Although we cannot exclude that plasma NT-proBNP and BNP show different patterns, the similar results for BNP and NT-proBNP in adults with aortic stenosis reported by Gerber et al.4 do not support this suspicion. More probably, the differences between paediatric and adult patients may be explained by the greater possibility for compensation of left ventricular function in younger patients than in elderly patients with aortic stenosis.

These differences according to age should be taken into account. We believe, the younger the patient, the less reliable is the measurement of natriuretic peptides for monitoring patients with aortic valve stenosis.

References

  1. Weber M, Arnold R, Rau M, Elsaesser A, Brandt R, Mitrovic V, Hamm C. Relation of N-terminal pro B-type natriuretic peptide to progression of aortic valve disease. Eur Heart J 2005 doi: 10.1093/eurheartj/ehi236. Published online ahead of print 21 March, 2005.
  2. Koch A, Singer H. Normal values of B type natriuretic peptide in infants, children, and adolescents. Heart 2003;89:875–878.[Abstract/Free Full Text]
  3. Koch A, Buheitel G, Hofner G, Nährlich L, Singer H. BNP levels in left heart obstruction. Z Kardiol 2002;91:16.[CrossRef][ISI][Medline]
  4. Gerber IL, Stewart RAH, Legget ME, West TM, French RL, Sutton TM, Yandle TG, French JK, Richards AM, White HD. Increased plasma natriuretic peptide levels reflect symptom onset in aortic stenosis. Circulation 2003;107:1884–1890.[Abstract/Free Full Text]




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