Plasma brain natriuretic peptide after long-term treatment for heart failure in general practice

Plasma brain natriuretic peptide (BNP) concentrations are known to have high sensitivity and specificity in the diagnosis of heart failure in newly symptomatic patients. The relationship of plasma BNP to cardiac function in stable patients on long-term established treatment for heart failure is unknown. Plasma BNP was assessed for its ability to predict echocardiographic abnormality in 100 patients receiving long-term treatment in general practice for a provisional diagnosis of heart failure.

BNP >35 pmol/l had a sensitivity and specificity of 69% and 67%, respectively, for a left ventricular ejection fraction of <45%. However, 19% of patients had an LVEF of below 45% whilst BNP was below 35 pmol/l. These patients, in whom a diagnosis of heart failure had been made years previously (mean 3.9 years), were all clinically stable on treatment.

These findings support the view that BNP can be restored to normal levels in well-compensated patients despite persisting significant systolic dysfunction and suggest that BNP assays may be helpful for monitoring adequacy of therapy. BNP assays will have limited utility in the diagnosis of cardiac impairment once anti-failure therapy is well established and symptoms have been abolished.