Incremental value of high-sensitivity C-reactive protein and N-terminal pro-B-type natriuretic peptide for the prediction of postoperative cardiac events in noncardiac vascular surgery patients

Abstract

High-sensitivity C-reactive protein (hs-CRP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are associated with the presence of coronary artery disease. The aim of this study was to assess the prognostic value of hs-CRP and NT-proBNP for postoperative cardiac events in noncardiac vascular surgery patients. In 592 patients, cardiac history, hs-CRP, and NT-proBNP levels were assessed preoperatively. Levels of hs-CRP of at least 6.5 mg/l and NT-proBNP of at least 350 pg/ml were defined as the optimal cut-off values for the prediction of postoperative cardiac events. The end point was the composite of 30-day cardiovascular death, Q-wave myocardial infarction, and troponin T release. Multivariable regression analysis was used to evaluate the association between hs-CRP, NT-proBNP and the end point. The performance of the risk models based on cardiac risk factors alone and the addition of both biomarkers was determined using C statistics. After adjustment for cardiac risk factors, site of surgery and type of procedure, elevated levels of hs-CRP (odds ratio 2.54; 95% confidence interval 1.50-4.30) and NT-proBNP (odds ratio 4.78; 95% confidence interval 2.71-8.42) remained independent predictors for postoperative cardiac events. When hs-CRP and NT-proBNP were added to the cardiac risk score, the C statistic improved from 0.79 to 0.84. A combined elevation of hs-CRP and NT-proBNP provided a seven-fold higher risk for postoperative cardiac events. Both hs-CRP and NT-proBNP have additional value in the prediction of postoperative cardiac events in vascular surgery patients. Their integrated use improves cardiac risk stratification.