In unexplained dyspnea on exertion in patients without known heart failure, without clear clinical signs of heart failure (diagnostic uncertainty). For the sake of completeness, it is best to also determine the D-dimers to exclude pulmonary embolism.
If heart failure is suspected on clinical grounds, NT-proBNP can therefore be used as an aid to rule out the disease. In primary care, the NT-proBNP determination has a high negative predictive value (88-98%). This means that a negative result indicates with great certainty that there is no heart failure. However, the positive predictive value is much lower (32-70%). An increased value can therefore also be the result of another cause (see below).
An increased NT-proBNP concentration can be used as an indication for additional echocardiographic examination or for referral to the cardiologist. The higher the increase in NT-proBNP, the sooner cardiological review should be performed.
Research has defined certain cut-off concentrations for NT-proBNP. Below these threshold values, heart failure is almost certainly excluded.
NT-proBNP also increases with age. In a chronic situation, the limit for a normal value is higher in patients ≥ 75 years of age to prevent overdiagnosis and unnecessary further examinations. In patients with unexplained dyspnea on exertion, these are the cut-off values:
- < 75 years: with NT-proBNP < 125 pg/ mL there is almost certainly no heart failure.
- ≥ 75 years: with NT-proBNP < 400 pg/ mL there is almost certainly no heart failure.
The cut-off values are also higher in acute heart failure than in chronic heart failure. In acute dyspnea, global heart failure is almost certainly excluded with an NT-proBNP < 300 pg/ml. As age increases, the limit value for the probability of acute heart failure also increases in the acute setting, as shown in this table.
