Aims Cardiac peptides have diagnostic and prognostic value in heart failure. Their plasma concentrations, however, are sensitive to rapid changes in haemodynamics. As blood sampling under standard conditions is not feasible in clinical practice, it is important to know which peptides are most resistant to change. Therefore, the present study investigated the differences in response to exercise between atrial natriuretic peptide, N-terminal proatrial natriuretic peptide, brain natriuretic peptide and the recently identified N-terminal probrain natriuretic peptide.
Methods and Results Fifty-two patients with chronic heart failure performed a symptom-limited graded bicycle exercise. Blood samples for determination of plasma concentrations of cardiac peptides were drawn at rest and at peak exercise. There was a significant difference in percentage increase in response to exercise between the four peptides (P<0·0001). N-terminal proatrial natriuretic peptide increased less than atrial natriuretic peptide (5±18% vs 59±58%;P<0·0001). The difference in increase between N-terminal probrain natriuretic peptide and brain natriuretic peptide was less distinct but still significant (24±24% vs 38±52%,P <0·05).
Conclusions Both N-terminal proatrial natriuretic peptide and N-terminal probrain natriuretic peptide increased less in response to exercise than their C-terminal counterparts. This implies that the circumstances under which blood sampling for measurements of N-terminal proatrial natriuretic peptide and N-terminal probrain natriuretic peptide should be performed are more favourable than the blood sampling conditions for atrial natriuretic peptide and brain natriuretic peptide.