The interrelationship between preoperative anemia and N-terminal pro-B-type natriuretic peptide: the effect on predicting postoperative cardiac outcome in vascular surgery patients.
BACKGROUND
N-terminal pro-B-type natriuretic peptide (NT-proBNP) predicts adverse cardiac outcome in patients undergoing vascular surgery. However, several conditions might influence this prognostic value, including anemia. In this study, we evaluated whether anemia confounds the prognostic value of NT-proBNP for predicting cardiac events in patients undergoing vascular surgery.


METHODS
A detailed cardiac history, resting echocardiography, and hemoglobin and NT-proBNP levels were obtained in 666 patients before vascular surgery. Anemia was defined as serum hemoglobin <13 g/dL for men and <12 g/dL for women. Troponin T measurements and 12-lead electrocardiograms were performed on postoperative days 1, 3, 7, and 30 and whenever clinically indicated. The primary end point of the study was the composite of 30-day postoperative cardiovascular death, nonfatal myocardial infarction, and troponin T release. Receiver operating characteristic curve analysis was used to assess the optimal cutoff value of NT-proBNP for the prediction of the composite end point. Multivariable regression analysis was used to assess the additional value of NT-proBNP for the prediction of postoperative cardiac events in nonanemic and anemic patients.


RESULTS
Anemia was present in 206 patients (31%) before surgery. Hemoglobin level was inversely related with the NT-proBNP levels (beta coefficient = -2.242; P = 0.025). The optimal predictive cutoff value of NT-proBNP for predicting the composite cardiovascular outcome was 350 pg/mL. After adjustment for clinical cardiac risk factors, both anemia (odds ratio [OR] 1.53; 95% confidence interval [CI]: 1.07-2.99) and increased levels of NT-proBNP (OR 4.09; 95% CI: 2.19-7.64) remained independent predictors for postoperative cardiac events. However, increased levels of NT-proBNP were not predictive for the risk of adverse cardiac events in the subgroup of anemic patients (OR 2.16; 95% CI: 0.90-5.21).


CONCLUSIONS
Both anemia and NT-proBNP are independently associated with an increased risk for postoperative cardiac events in patients undergoing vascular surgery. NT-proBNP has less predictive value in anemic patients.
Department of Vascular Surgery, Erasmus Medical Center, Rotterdam, The Netherlands.
Dustin
D
Goei
Willem-Jan
WJ
Flu
Sanne E
SE
Hoeks
Wael
W
Galal
Martin
M
Dunkelgrun
Eric
E
Boersma
Ruud
R
Kuijper
Jan-Peter
JP
van Kuijk
Tamara A
TA
Winkel
Olaf
O
Schouten
Jeroen J
JJ
Bax
Don
D
Poldermans
D000368:Aged; D000740:Anemia / Q000097:blood / Q000150:complications*; D015415:Biomarkers / Q000097:blood; D004562:Electrocardiography; D005260:Female; D006331:Heart Diseases / Q000097:blood / Q000209:etiology* / Q000401:mortality; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D016017:Odds Ratio; D010446:Peptide Fragments / Q000097:blood*; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D020107:Troponin T / Q000097:blood; D014656:Vascular Surgical Procedures / Q000009:adverse effects* / Q000401:mortality
D015415:Biomarkers; D006454:Hemoglobins; D010446:Peptide Fragments; D020107:Troponin T; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain