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.

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.

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).

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