A new blood test that measures a particular marker of cardiac distress can markedly improve the ability to diagnose or exclude congestive heart failure in patients with shortness of breath who come to hospital emergency departments.

The report from researchers at Massachusetts General Hospital ( MGH ) finds that measuring levels of a protein called NT-proBNP (aminoterminal pro-brain natriuretic peptide ) was significantly better at identifying heart failure than was standard clinical evaluation.

The diagnosis of heart failure may be difficult to make because its typical symptoms can overlap with those of other conditions. Missing a heart failure diagnosis can put patients at high risk of serious problems, including death, but overdiagnosis may lead patients to receive unnecessary treatment.

Proteins called natriuretic peptides are produced when the cardiac muscle is under stress.

In 2002, the newest generation of natriuretic peptide assays became available.

The PRIDE study ( The N-terminal Pro-BNP Investigation of Dyspnea in the Emergency department ) was conducted to determine the usefulness of a test for NT-proBNP in evaluating emergency patients.

About 600 patients who presented in the MGH Eemergency Department with dyspnea were enrolled in the study.
The clinical diagnosis of acute congestive heart failure ( CHF ) was determined by study physicians who were blinded to NT-proBNP results.

The primary end point was a comparison of NT-proBNP results with the clinical assessment of the managing physician for identifying acute CHF.

In addition to standard evaluation of symptoms, a blood sample was drawn for NT-proBNP measurement.

When investigators reviewed NT-proBNP levels, they found that the protein's concentrations were significantly higher in patients eventually diagnosed with heart failure and highest in those with most severe symptoms.

For identifying heart failure in these emergency patients, the test alone was significantly more accurate than was the physicians' original likelihood assessment, but a combination of NT-proBNP levels and physician judgement produced the most accurate method of diagnosis.

NT-proBNP at cutpoints of > 450 pg/ml for patients < 50 years of age and > 900 pg/ml for patients ≥ 50 years of age were highly sensitive and specific for the diagnosis of acute CHF ( p <0.001 ).
An NT-proBNP level < 300 pg/ml was optimal for ruling out acute CHF, with a negative predictive value of 99%.

Source: The American Journal of Cardiology, 2005


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