Mid-regional pro-atrial natriuretic peptide is a strong predictor of outcome in an unselected cohort of critically ill patients

Introduction

Atrial natriuretic peptide (ANP) is a strong predictor of outcome in patients with heart failure, various other cardiovascular diseases and in patients with systemic inflammatory response syndrome and sepsis. Furthermore, ANP is elevated in patients with kidney disease. We aimed to test the prognostic potency of the precursor molecule mid-regional pro-atrial natriu-retic peptide (MR-pro-ANP) in an unselected cohort of critically ill patients.

Methods

Between August 2004 and February 2006, a total of 294 patients (191 males, age 63.8 ± 14.7 years) admitted to our ICU were studied. The mean SAPS2 and APACHE II score were 52 ± 23 and 24 ± 11, respectively. Two hundred and three patients (69.1%) were on intravenous inotropic support, 30 patients had additional mechanical circulatory support (23 intraaortic balloon counterpulsation (7.8%), eight extracorporeal membrane oxygenation (2.7%), three left ventricular assist device (0.9%)). Two hundred and five patients (69.7%) were mechanically ventilated, and 59 patients (20.1%) presented with acute renal failure. Plasma samples for determination of MR-pro-ANP were obtained on admission in all patients. As MR-pro-ANP values were not normally distributed, log MR-pro-ANP values were used for analysis.

Results

Two hundred and thirty-five patients (79.9%) survived to ICU discharge and 59 patients died (21.1%). Log MR-pro-ANP plasma levels were significantly higher in patients who died than in ICU survivors (2.76 ± 0.39 pmol/l vs 2.50 ± 0.38 pmol/l, respectively, P < 0.0001). In the Kaplan–Meier analysis of 28-day survival, patients with log MR-pro-ANP plasma-levels above the median had significantly lower survival rates compared with patients with log MR-pro-ANP plasma levels below the median (P = 0.02).

Conclusion

Our data show that elevated plasma levels of MR-pro-ANP at ICU admission are associated with an adverse outcome in an unselected cohort of critically ill patients.