Serum N-terminal pro brain natriuretic peptide (NTproBNP) in perioperative cardiac surgical patients

Introduction

Brain natriuretic peptide (BNP) is released from stretched ventricular wall. BNP particularly the N-terminal portion of proBNP (NTproBNP) is a sensitive marker of congestive heart failure and predictor of outcome [1]. Variations in NTproBNP in cardiac surgical patients are not well described [2]. We investigated changes in NTproBNP in relation to clinical progress in open heart surgery patients.

Methods

We measured serum concentrations of NTproBNP in 15 perioperative cardiac surgical patients in a pilot observational study using an electrochemiluminescent sandwich immunoassay (Elecsys 2010, Roche Diagnostics: interassay c.v. 5.0% at 380 ng/l, 4.4% at 8700 ng/l, 5.0% at 13000 ng/l, detection limit 20 ng/l, upper measuring limit 25,000 ng/l). We collected samples on induction of anaesthesia, at the end of the surgery, 12 hourly for 3 days, then daily for 3 days.

Results

Two patients of 15 died. One had preoperative right ventricular failure and a baseline NTproBNP of >25,000 ng/l falling to 18613 ng/l postoperatively but rising to >25,000 ng/l until death. The other with left ventricular failure and NTproBNP of 3720 ng/l had sustained postoperative levels of >25,000 ng/l until death. Two patients were hemofiltered and NTproBNP rose to >25,000 ng/l postoperatively. Eight patients with a baseline NTproBNP <700 ng/l had uncomplicated recoveries. Of five patients with a baseline NTproBNP >1000 ng/l two died and two had prolonged ICU stays. Baseline NTproBNP was missing for two patients, one of whom died (Fig. 1).

Figure 1

NTproBNP concentrations in 15 heart surgery patients.

Conclusions

Changes in serum NTproBNP in cardiac surgical patients may predict clinical course.