Neurohormonal activation and diagnostic value of cardiac peptides in patients with suspected mild heart failure

Background Data describing activation of brain natriuretic peptide (BNP) system relative to the renin–angiotensin–aldosterone system (RAAS) are sparse in the early phase of heart failure (HF). Aims To compare activation of BNP system relative to RAAS hyperactivity and to assess diagnostic accuracy of cardiac peptides to detect any left ventricular dysfunction (LVD) in patients referred from primary care with suspected HF before institution of medical therapy. Methods Of 166 referred patients 150 were consecutively included (14 were excluded and two refused consent). Echocardiography and measurements of neurohormonal activity were performed. Systolic dysfunction (LVSD) was defined as an ejection fraction ≤ 0.45. Abnormal left ventricular filling was determined by a combination of Doppler techniques. Results LVSD with concomitant abnormal left ventricular filling was present in 22 patients, and abnormalities in left ventricular filling alone were present in 58. Median BNP were 307 and 37 pg/ml while median N-terminal proBNP (NT-proBNP) were 2285 and 199 pg/ml in the two groups respectively, and were significantly lower in patients without LVD (BNP: 8 pg/ml and NT-proBNP: 55 pg/ml, P < 0.0001). NT-proBNP demonstrated a weak negative correlation with renin (r = − 0.18, P = 0.03) and aldosterone (r = − 0.18, P = 0.03), but no significant correlation with Ang II (r = − 0.14, P = 0.10) or noradrenaline (r = 0.11, P = 0.19). Renin correlated well with Ang II (r = 0.85, P < 0.0001), and aldosterone (r = 0.41, P < 0.0001). RAAS and noradrenaline demonstrated no diagnostic potential for the diagnosis of any LVD with areas under ROC curves close to 0.50. The area was 0.93 (95% CI 0.90–0.98) for BNP and 0.95 (0.91–0.99) for NT-proBNP. In 5–10% of patients with LVD, BNP and NT-proBNP were under the selected thresholds. Conclusion Patients with LVD demonstrated considerable activation of the BNP system, whereas RAAS hyperactivity could not be demonstrated. Thus, BNP and NT-proBNP had a considerable diagnostic potential even in patients with mild HF.