Background: B-type natriuretic peptides (BNP) are acknowledged markers of acute and chronic heart failure. Insufficient data exist, however, regarding their diagnostic usefulness in cardiac surgery, particularly in coronary patients.
Aim: To assess diagnostic accuracy of preoperative value of NT-proBNP level as a predictor of short-term postoperative complications in subjects undergoing coronary artery bypass grafting (CABG).
Methods: This pilot study included 100 consecutive patients scheduled for elective CABG, including 24 females and 76 males (mean age 65.9 ± 9.1 years). Exclusion criteria were: significant valvular disorders, off-pump procedure, renal failure (GFR < 60 mL/min/1.73 m2), low ejection fraction (< 30%), intra-aortic balloon pump counterpulsation (IABP), use of inotropic agents, atrial fibrillation (AF), and implanted pacemaker or defibrillator. The NT-proBNP level was measured on the day of the surgery before induction of anaesthesia. We investigated short-term postoperative complications, defined as those occurring within 30 days or before hospital discharge.
Results: Median NT-proBNP concentration was 526.0 pg/mL (IQR 156.0-1150.0). None of patients died postoperatively. Excessive drainage (> 850 mL) was found in 13 (13%) patients and 22 (22%) subjects required transfusions. Prolonged mechanical ventilation (> 12 h) was necessary in 15 (15%) patients and respiratory failure occurred in 2 (2%) of them. Postoperative AF was present in 34 (34%) subjects. Perioperative myocardial infarction was diagnosed in 2 (2%) persons. Low cardiac output was present in 9 (9%) patients. Haemodynamic support with the use of IABP was necessary in 7 (7%) patients and inotropic drugs were used in 61 (61%) subjects. Stroke or delirium was diagnosed in 1 (1%) subject. The NT-proBNP level correlated with the operative risk estimated by logistic and additive EuroSCORE: r = 0.558 (95% CI 0.406-0.680; p < 0.001) and r = 0.551 (95% CI 0.397-0.674; p < 0.001), respectively. The NT-proBNP level correlated significantly with the length of Intensive Care Unit (ICU) stay and hospital stay: r = 0.412 (95% CI 0.238-0.566; p < 0.001) and r = 0.547 (95% CI 0.393-0.672; p < 0.001), respectively. The NT-proBNP level was a predictor of postoperative prolonged mechanical ventilation, respiratory failure, AF, IABP use, inotropic support and postoperative platelet transfusions (p < 0.05 for all). However, good or very good diagnostic accuracy was found only in relation to mechanical ventilation (AUROC = 0.854), respiratory insufficiency (AUROC = 0.867), IABP use (AUROC = 0.889), and milrinone use (AUROC = 0.929).
Conclusions: Preoperative assessment of NT-proBNP level in CABG patients could be a valuable diagnostic method for predicting several postoperative complications, especially pulmonary outcomes and requirement for haemodynamic support, and it correlated with the length of ICU stay and hospital stay.