[Personal experience with determination of NT-proBNP in clinical practice]

Recently in the literature information is found on estimation of natriuretic peptides in the differential diagnosis of dyspnoea. Because in the Czech Republic since the beginning of 2002 routine estimation of NT-proBNP is available (analyzer Elecsys 2010), the objective of our work was to find out whether it is possible to use in the everyday practice of a district hospital estimation of NT-proBNP to differentiate dyspnoea with affection of the heart muscle from other types of dyspnoea.

A group of 33 patients from the medical department of the Sternberk hospital was examined who attended on account of dyspnoea and lacked signs of acute coronary syndrome. All probands were diagnosed on the basis of defined criteria; according to the final diagnosis the patients were divided into three groups: group "LV" was formed by dyspnoic patients with organic affection of the left ventricle and signs of congestion in the lesser circulation, group "non-LV" was formed by patients where no organic affection of the left ventricle was found but other heart disease was present. Group "non-C" was formed by patients where a cardiac cause of dyspnoea was ruled out. In all patients on admission NT-proBNP was assessed.

33 probands were examined, 18 men and 15 women, mean age 74.5 years. 25 probands the dyspnoea was classified as dyspnoea with affection of one of the cardiac compartments [19 of them had signs of organic affection of the left ventricle (group "LV")]; in 6 probands no signs of organic left ventricular affection were found (group "Non-LV"). The remaining 8 patients had no signs of any disease of the heart muscle, valves, septa, endocardium and pericardium (group "Non-C). The baseline values of NTpro-BNP were closely associated with the NYHA classification (grade II--median 55.3 pmol/l (469 ng/l, grade III--median 399.3 pmol/l (3384 ng/l), grade IV--median 724.7 pmol/l (6294 ng/l), the differences were statistically significant, p < 0.05). The dyspnoic probands with concurrent affection of some cardiac compartment (groups "LV" and "Non-LV") had a NT-pro BNP concentration significantly higher than probands without affection of the heart (group "Non-C") (median 589.5 pmol (4996 ng/l as compared with 62.9 pmol/l (533 ng/l, p < 0.01). In the group of probands with heart disease probands with affections of the left ventricle (group "LV") had significantly higher NT-proBNP values than subjects without affection of the LV and without any heart disease (groups "Non-LV" and "Non-C") (median 670.6 pmol/l (5683 ng/l) as compared with 187.5 pmol/l (1589 ng/l), p < 0.01). In hospitalized probands after treatment along with improved cardiopulmonary compensation also a significant drop of NT pro-BNP occurred (median 303 pmol/l (3967.7 ng/l to 211 pmol/l (2561 ng/l), p < 0.05). When looking for associations between anamnestic, laboratory and clinical data we found that the value of NT-proBNP is associated with dyspnoea with cardiac affection (groups "LV" + "Non-LV", correlation coefficient 0.48), with the left ventricular ejection fraction (correlation coefficient 0.52) and the baseline NYHA classification (correlation coefficient 0.36). In the examined group we did not find an association between NT-proBNP and age, sex, diabetes mellitus, hypertension, the presence of atrial arrhythmias, aortal stenosis, or the width of the left atrium. When using as cut-off for NT-proBNP 59 pmol/l (500 ng/l), the sensitivity of NT-proBNP for dyspnoea with affection of the cardiac compartments was 92% and the specificity 67%.

Assessment of NT-proBNP is an important diagnostic acid in the differential diagnosis of dyspnoea.