Plasma NT-proBNP measured pre-discharge provides useful prognostic information following hospitalisation with acute LVF.

Elevated plasma natriuretic peptide levels after AMI (acute myocardial infarction) are associated with adverse outcome. The aim of the present study was to examine the relationship of plasma N-ANP (N-terminal pro-atrial natriuretic peptide) and N-BNP (N-terminal pro-B-type natriuretic peptide) with mortality and heart failure following AMI. We studied 403 patients with AMI. Blood was sampled for measurement of N-ANP and N-BNP on a single occasion between 72 and 96 h after symptom onset. Natriuretic peptide levels were related to all-cause mortality and heart failure episodes. During follow up (median, 462 days; range 5-764), 43 (10.7%), 25 (6.2%) and 49 (12.2%) patients suffered death, heart failure hospitalization and outpatient heart failure respectively. Only N-BNP (P < 0.0005), N-ANP (P = 0.005) and previous AMI (P = 0.016) were independently predictive of death. N-BNP, but not N-ANP, predicted 30-day mortality. N-ANP, but not N-BNP, predicted mortality after 30 days. N-BNP was the better predictor of heart failure. N-ANP and N-BNP were above the median in 35 and 38 respectively, of 43 patients who later died. N-ANP, N-BNP, or both were above the median in 41 out of 43 patients. Of 25 patients hospitalized with heart failure, N-ANP and N-BNP was above the median in 20 and 24 respectively, and one or other was elevated in all cases. Above-median N-ANP predicted 36 and N-BNP predicted 41 out of 49 episodes of outpatient heart failure. One or other peptide was above the median in 45 out of 49 patients. Our results indicate that N-BNP predicts 30-day and N-ANP >30-day mortality. We conclude that consideration of both N-ANP and N-BNP identifies a greater number of patients at risk of death or heart failure than either peptide alone.

Cardiotrophin-1 (CT-1) leads to a specific form of ventricular hypertrophy characterized by sarcomeres added in series, and has been reported to be elevated in heart failure. Previous competitive assays for CT-1 necessitate the extraction of plasma and involve prolonged incubations. We describe the development of a non-competitive assay for CT-1 that can measure plasma levels without the need for extraction. Two antibodies specific for the mid-section (amino acids 105-120) and C-terminal (amino acids 186-199) portions of CT-1 were developed in rabbits. One antibody was immobilized and used as the capture antibody. The other antibody was affinity purified and biotinylated. Unextracted plasma was incubated with these antibodies, and detection was with methylacridinium ester-labelled streptavidin. Plasma was obtained from 40 patients with heart failure and 40 normal control subjects. The non-competitive assay demonstrated a linear increase in chemiluminescence (measured as relative light units) with increasing amounts of full-length recombinant CT-1, with no evidence of a hook effect at high concentrations. The lower limit of detection was 2.9 fmol/ml. Intra-assay coefficients of variation ranged from 3.1% to 4.2% in the 10-40 fmol/well concentration range, and interassay coefficients of variation ranged from 3.5% to 4.5% in the 550-950 fmol/ml range. Measurements of CT-1 levels in patients with heart failure (median 166.5 fmol/ml; range 49.5-2788 fmol/ml) revealed very significantly elevated levels compared with those in normal controls (median 43.5 fmol/ml; range 11.2-258.6 fmol/ml; P<0.0001 by Mann-Whitney test). At a CT-1 concentration of 68 fmol/ml, sensitivity and specificity were 95% and 82.5% respectively. Thus this new non-competitive immunochemiluminometric assay for CT-1 could successfully detect full-length recombinant CT-1 in unextracted plasma, and demonstrated that plasma levels of CT-1 were significantly elevated in patients with heart failure.