Plasma brain natriuretic peptide and cardiac troponin I concentrations after adult cardiac surgery: association with cardiovascular death, postoperative cardiac, renal and pulmonary dysfunction

Introduction

B-type natriuretic peptide (BNP) and troponin levels can predict outcome after acute myocardial infarction and after acute heart failure. The purpose of this study was to evaluate the prognostic implication of high postoperative BNP and cardiac troponin I concentrations in adult patients undergoing cardiac surgery.

Methods

A prospective study was carried out in a total of 181 consecutive patients undergoing elective coronary artery bypass or valve surgery patients. BNP and cardiac troponin I concentrations were measured immediately after surgery (day 0), and at day 1 after surgery (day 1). Postoperative cardiac dysfunction was defined as low output cardiac or hemodynamic instability requiring inotropic support for >24 hours. Pulmonary dysfunction was defined as postoperative hypoxemia (rate PO₂/FiO₂ < 200) or time to extubation longer than 360 minutes. Univariate and multivariate analyses were performed.

Results

A significant secretion of BNP was observed after cardiac surgery. Independent predictors of cardiac dysfunction were higher values of BNP and troponin measured on day 0 and on day 1 (P = 0.0001), higher levels of CKMB (P = 0.006), and lower ejection fraction (P = 0.05). Independent predictors of pulmonary dysfunction were elevation of BNP on day 0 (P = 0.0005) and on day 1 (P = 0.02). BNP levels higher than 300 pg/ml were associated with higher rates of renal failure (P = 0.0001). A BNP level higher than 300 pg/ml and a troponin level higher than 15 ng/ml was associated with a higher risk of mortality (P = 0.0001).

Conclusion

Postoperative BNP and cardiac troponin are independent predictors of mortality and cardiac and pulmonary dysfunction after cardiac surgery. Higher levels of BNP are also correlated with higher rates of renal failure after cardiac surgery.