Testing for N-terminal proB-type natriuretic peptide (NT-proBNP) may be a useful way of distinguishing lung disease from heart failure (HF) in patients admitted with dyspnea to an emergency room.

'The most astonishing thing about these results is that the BNP values are so different between heart and lung patients,' said Jens Svanegaard (Sygehus Fyn, Faaborg, Denmark) to InCirculation.net, after presenting the results at the Heart Failure Update 2002 meeting in Oslo, Norway.

Svanegaard and colleagues asked 74 primary care physicians to refer patients with dyspnea of less than two weeks duration into the study, and propose a diagnosis for the complaint at the same time.

A final diagnosis was then made by the researchers on the basis of clinical examinations, ECG and X-ray results, blood tests, and early and late echocardiography.

In all, 346 patients were included in the study, 51per cent of whom were women. Although 54 per cent of patients were referred due to suspected heart failure, only 23 per cent were finally diagnosed with the condition.

The researchers note that their HF definition was somewhat different to those in European Society of Cardiology guidelines.

In this study, HF was diagnosed if patients had an ejection fraction under 45 per cent, hypertrophy and hypertension on echocardiography, uncontrolled arrhythmias, valve failure with an indication for operation, and right ventricular failure.

Results showed that those patients with heart failure, or heart failure and lung disease, had extremely elevated BNP values, compared with those who had no such diagnosis (p<0.0001).

On average, HF patients had a NT-proBNP level of 1570 pg/ml, and those with valve disease had an average value of 2956 pg/ml. Out of 80 patients with heart failure, 64 were identified from high BNP levels (80%). Of the 16 cases not recognised by the test, 10 had hypertrophy of the left ventricle.

In contrast, only 15 out of the 128 patients with dyspnea due to lung disease had elevated NT-proBNP values (11.7%).

'If a patients presents with dyspnea then the big question is 'is it lung problems or is it HF?' said Svanegaard.

He concluded: 'Nt-proBNP is able to exclude HF with an overall predictive value of a negative test of 95 per cent. In case of normal values, consider another diagnosis.'