Abstract 2667: Comparison of Mid-regional Pro-atrial Natriuretic Peptide (MR-proANP) and N-terminal Pro B-type Natriuretic Peptide (NT-proBNP) as Predictors of Survival in Patients with Chronic Heart Failure (CHF)
BACKGROUND: Natriuretic peptides are powerful predictors of survival in CHF. ANP comprises 98% of all natriuretic peptides in the circulation. Its relative instability compared to other natriuretic peptides limits its prognostic value. Mid-regional proANP (MR-proANP) is highly stable in vivo and ex vivo.
METHODS: We investigated 536 CHF patients (age 61±12 yrs, NYHA class 2.6±0.8, LVEF 30±10%, N-terminal pro-B-type natriuretic peptide [NT-proBNP] 3581±6513 pg/mL, serum creatinine 112±43 μmol/L, 94% male, 71% ischemic etiology) from 5 European centers. MR-proANP was detected using a novel commercial assay (B.R.A.H.M.S. Seristra Luminescence Immuno Assay). The functional assay sensitivity (inter assay CV 24 hours. Median MR-proANP in 325 healthy individuals in previous investigations was 45 pmol/L (95% CI 43– 49 pmol/L).
RESULTS: Mean MR-proANP in our CHF population was 334±306 pmol/L (range: 24.5–2280). MR-proANP increased with NYHA class (I: 133±94, II: 243±202, III: 379±301, IV 626±446 pmol/L, p<0.0001 for all comparisons except NYHA I vs II [p=0.0269]). In a multivariate model, MR-proANP correlated with NT-proBNP (r=0.49, p<0.0001), serum creatinine (r=0.24, p<0.0001), NYHA class (r=0.18, p0.3). During follow-up (92 to 4879 days in survivors, median 467 days), 149 patients (28%) died after 1 to 3678 days (median 310 days). The 1- and 5-year mortality were 15% (95% CI 11–19%) and 41% (95% CI 36 – 47%), respectively. In univariate Cox proportional hazard analysis, MR-proANP (chi square 102.4), NT-proBNP (chi square 73.6), NYHA class, serum creatinine, LVEF (all p<0.0001), and age (p=0.003) all predicted survival. Increasing MR-proANP was a predictor of poor survival (hazard ratio 1.100 per 100 pmol/L, 95% CI 1.047 to 1.156, p=0.0002), independently of NT-proBNP, age, sex, etiology, LVEF, NYHA class, and creatinine. In this model, NT-proBNP did not predict survival (p=0.1149). 18-month mortality was 4% (95% CI 0 – 8%), 24% (95% CI 14–34%), 37% (95% CI 25– 49%), and 77% (95% CI 67– 87%) in ascending quartiles of MR-proANP (p<0.0001).
CONCLUSIONS: MR-proANP is a powerful new predictor of mortality in patients with CHF independently of established prognosticators. Its predictive power exceeded that of NT-proBNP in our study population.