SAN DIEGO — Preoperative elevated levels of N-terminal pro-B-type natriuretic peptide are an excellent predictor of mortality in patients undergoing cardiac surgery, even when adjusted for currently used scoring systems, Dr. Brian H. Cuthbertson reported during a poster session at the annual meeting of the American Association for Clinical Chemistry.
Dr. Cuthbertson and his associates measured the preoperative NT-proBNP levels from blood samples in 541 consecutive patients who underwent cardiac surgery at Aberdeen Royal Infirmary, Aberdeen, Scotland. They followed the patients postoperatively for a median of 18 months to assess mortality.
The researchers found that the median NT-proBNP levels were significantly higher in the patients who died, compared with those who survived (1,173 pg/mL and 282 pg/mL, respectively).
In addition, patients who died were significantly older than those who survived (median 73 years and 67 years, respectively). They also had significantly higher scores on the European System for Cardiac Operative Risk Evaluation (EuroSCORE) than did survivors (median 6.6 and 2.9, respectively).
Median estimated glomerular filtration (eGFR) rate was significantly lower in patients who died, compared with survivors (62 mL/min per 1.73 m
In a Kaplan Meier analysis for survival, patients in the highest tertile for NT-proBNP showed the highest mortality, compared with those in the lower two tertiles (12.8% vs. 2.2%).
A multivariate model that included NT-ProBNP, EuroSCORE, age, gender, previous myocardial infarction, hypertension, diabetes, smoking, and eGFR showed that only elevated levels of NT-ProBNP and older age remained significant predictors of mortality.
“Preoperative measurement of NT-proBNP may help identify patients at higher risk who would benefit from further optimization of clinical status prior to surgery,” the researchers concluded.
The study, which is the largest of its kind, will eventually enroll 1,000 patients, according to Dr. Cuthbertson.