Plasma N-terminal pro-B-type natriuretic peptide as a predictor of perioperative and long-term outcome after vascular surgery
Objective: N-terminal pro-B-type natriuretic peptide (NT-proBNP) is secreted by the heart in response to ventricular wall stress and has prognostic value in patients with heart failure, coronary artery disease, and heart valve abnormalities. Postoperative and long-term outcome is also related to these risk factors. This study assessed the additional prognostic value of NT-proBNP levels as a simple objective risk marker for postoperative cardiac events among vascular surgery patients. Methods: A detailed cardiac history (angina, myocardial infarction, age >70 years, diabetes mellitus, renal failure, stroke, heart failure), resting echocardiography, and NT-proBNP levels were obtained in 400 vascular surgery patients. Postoperative troponin-T levels and an electrocardiogram were obtained on days 1, 3, 7, and 30, and whenever clinically indicated. Patients were monitored every 6 months at the outpatient clinic. Study end points were perioperative cardiac events (ie, composite of cardiac death, myocardial infarction, and troponin release) and long-term all-cause mortality. The additional value of NT-proBNP was assessed with multivariable regression analysis. The optimal cutoff value was assessed by receiver operating characteristic curve analysis. Results: Postoperative troponin T release occurred in 79 patients (20%). Cardiac risk factors were used to classify patients as low (0 risk factors), intermediate (1 to 2), and high (>3) cardiac risk (event rate of 7%, 15%, and 37%, respectively). The median NT-proBNP level was 206 pg/mL (interquartile range, 80-548 pg/mL). The risk of postoperative cardiac events was augmented with increasing NT-proBNP, irrespective of underlying cardiac risk factors and type of vascular surgery. In addition to cardiac risk factors only (C index, 0.66) or cardiac risk factors and site and type of surgery (C index, 0.81), NT-proBNP was an excellent tool for further risk stratification (C index, 0.86), with an optimal cutoff value of 350 pg/mL. In multivariate analysis, NT-proBNP >350 pg/mL remained significantly associated with perioperative cardiac events (odds ratio [OR], 4.7; 95% confidence interval [CI], 2.1-10.5, P < .001). NT-proBNP >350 pg/mL was also associated with an independent 1.9-fold (95% CI 1.1-3.2) increased risk for long-term mortality during a median follow-up of 2.4 years. Conclusion: NT-proBNP is an independent prognostic marker for postoperative cardiac events and long-term mortality in patients undergoing different types of vascular surgery and might be used for preoperative cardiac risk stratification.