B-type natriuretic peptide as a surrogate marker for survival in patients undergoing cardiac surgery

Abstract

Background: B-type natriuretic peptide (BNP) is a biomarker predicting morbidity and mortality in patients with congestive heart failure. However, the usefulness of preor postoperative BNP levels in patients undergoing cardiac surgery remains uncertain. We sought to determine the association of pre or postoperative BNP levels on mortality in patients undergoing cardiac surgery under cardiopulmonary bypass (CPB).

Methods: This study retrospectively evaluated 1,642 patients undergoing cardiac surgery under CPB over 2 years. The primary outcomes were 30-day and overall mortality after cardiac surgery.

Results: The 30-day mortality rate was 3.0% (n=49), and the overall mortality occurred in 118 patients during the mean follow-up period of 24.9 +/- 8.9 months. In multivariable analyses, preoperative BNP level was not significantly associated with 30-day [odds ratio (OR), 1.03; 95% confidence interval (CI), 0.99- 1.06; P=0.06] or overall [hazard ratio (HR), 1.01; 95% CI, 0.98-1.03; P=0.50] mortalities. However, the postoperative BNP level was significantly associated with 30-day (OR, 1.05; 95% CI, 1.02-1.09; P=0.001) and overall (HR, 1.03; 95% CI, 1.01-1.04; P=0.01) mortalities. As a sensitivity analysis, postoperative BNP levels were divided into quartiles. The top quartile (>_484 pg/mL) was identified as a strong predictor of overall mortality (HR, 2.18; 95% CI, 1.14-4.19; P=0.02).

Conclusions: Preoperative BNP level was not associated with mortality after cardiac surgery. However, postoperative BNP level was associated with mortality after cardiac surgery, especially in patients with high levels (>_484 pg/mL). Further studies in larger cohorts are necessary to validate these results.