O peptídeo natriurético tipo B (BNP) como preditor de mortalidade a longo prazo em pacientes com síndrome coronariana aguda sem supradesnível do segmento ST

Abstract

Background: In spite of the large knowledge gathered on mortality prediction markers in acute coronary syndrome, their long term capability remains unknown. B-type natriuretic peptide (BNP) have been extensively evaluated, but the existing evidence is restricted for short and intermediate-term. Objectives: To determine if BNP is an independent predictor of long term all-cause mortality in non-ST segment elevation acute coronary syndrome (NSTEACS). Methods: Between 1st January 2002 and 31st December 2003, 224 consecutive patients seen in the emergency department with NSTEACS were enrolled. Admission plasma BNP measurement was incorporated in the diagnostic protocol, with the purpose of correlating its value with mortality at the end of the follow-up. Results: Patients were followed for 9.34 years (median), median age=71.5 years (IQ range=60.5;79.0) and mostly males (62.9%). Arterial hypertension was observed in 82.1% and diabetes in 23.7%. Unstable angina (UA) was diagnosed in 52.2% and non-ST segment elevation acute myocardial infarction (NSTEAMI) in 47.8%. Median BNP was 81.9 pg/ml (IQ range=22.2; 225) and mortality rate was correlated with increased BNP quartiles: 14.3; 16.1; 48.2; and 73.2% (p<0.0001). ROC curve disclosed 100 pg/ml as the best BNP cut-off value for mortality prediction with an area under the curve (AUC) of 0.79 (95% CI=0.72-0.85), being a strong late mortality predictor: BNP<100 pg/ml=17.3% vs. BNP&#8805;100 pg/ml=65.0%, p<0.001, RR=3.76 (95% CI=2.49-5.63). BNP achieved significant prognostic power both in patients with (26.7 vs. 71.2%, p<0.001) and without (12.9 vs. 56.8%, p<0.001) left ventricular disfunction, and in those with UA (18.7 vs. 48.6%, p=0.001) and NSTEAMI (14.9 vs. 75,0%, p<0.001). On logistic regression analysis, age>72 years (OR=3.79, 95% CI=1.62-8.86, p=0.002), BNP&#8805;100 pg/ml (OR=6.24, 95% CI=2.95-13.23, p<0.001) and estimated glomerular filtration rate (OR=0.98, 95% CI=0.97-0.99, p=0.049) were independent late-mortality predictors. Conclusions: Admission BNP is a strong and independent long-term mortality predictor in NSTEACS.