NT-ProBNP in outpatients after myocardial infarction: interaction between symptoms and left ventricular function and optimized cut-points.
BACKGROUND
N-terminal pro-brain natriuretic peptide (NT-proBNP) allows us to rule out left ventricular dysfunction (LVD) in the general population at a recommended cut-off concentration of 125 pg/mL. It was our objective to reassess this cut-point in outpatients after myocardial infarction.


RESULTS
NT-proBNP was assessed in 418 randomly selected outpatients who had experienced myocardial infarction and 352 siblings who had not experienced myocardial infarction (control). Left ventricular ejection fraction (LVEF) and mass-index (LVMI) were assessed by echocardiography. NT-proBNP was elevated in outpatients after myocardial infarction (mean [+/-SEM], 305 +/- 25 pg/mL vs control, 84 +/- 8 pg/mL; P < .01) and was correlated inversely with LVEF ( P < .001). When patients were stratified according to the presence or absence of heart failure, NT-proBNP was elevated significantly throughout all LVEF strata (each P < .05). On regression analysis, NT-proBNP was correlated independently with LVEF, LVMI, heart failure, and glomerular filtration rate (all P < .01). In patients with heart failure, the optimal cut-point for the detection of an LVEF <35% was 348 pg/mL (sensitivity 80%; specificity 69%) and for the detection of an LVEF <45% was 260 pg/mL (sensitivity 60%; specificity 60%). The relative risk for LVD in the presence of elevated NT-proBNP increased from 2.7 to 7.7 (EF < 35%) and from 1.4 to 2.4 (EF < 45%) when these cut-points were applied instead of the 125 pg/mL cut-point. An LVEF of <35% could be ruled out in symptomatic outpatients after myocardial infarction with a negative predictive value of 97% (cut-point 348 pg/mL) and in asymptomatic outpatients after myocardial infarction with a negative predictive value of 98% (cut-point 157 pg/mL).


CONCLUSIONS
NT-proBNP is higher in outpatients after myocardial infarction than in the general population. In symptomatic patients, a cut-point of 348 pg/mL yields satisfactory sensitivity and specificity for the detection of significant LVD (EF < 35%). Furthermore, significant LVD can be virtually ruled out in symptomatic and asymptomatic outpatients after myocardial infarction at below-threshold concentrations.
Luchner
Andreas
A
Klinik und Poliklinik für Innere Medizin II, University of Regensburg, Regensburg, Germany.
Hengstenberg
Christian
C
Löwel
Hannelore
H
Buchner
S
S
Schunkert
Heribert
H
Riegger
Günter A J
GA
Holmer
Stephan
S
D000368:Aged; D000553:Ambulatory Care; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D004452:Echocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009203:Myocardial Infarction / Q000097:blood* / Q000175:diagnosis* / Q000503:physiopathology; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D011237:Predictive Value of Tests; D012107:Research Design; D012680:Sensitivity and Specificity; D018487:Ventricular Dysfunction, Left / Q000097:blood* / Q000175:diagnosis; D016277:Ventricular Function, Left / Q000502:physiology
D015415:Biomarkers; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain