ABC | Volume 114, Nº4, April 2020

Original Article Prognostic Value of NT-proBNP versus Killip Classification in Patients with Acute Coronary Syndromes Thiago M. B. Souza, 1 Antônio Maurício S. Cerqueira Jr., 1 Jessica G. Suerdieck, 1 Nicole C. de Sá, 1 Gabriella S. Sodré, 1 Vitor C. A. Correia, 1 Yasmin F. Lacerda, 1 Leticia L. Fonseca, 1 Marcia M. Noya-Rabelo, 2 Luis C. L. Correia 1 Escola Bahiana de Medicina e Saúde Pública, 1 Salvador, BA – Brazil Hospital São Rafael, 2 Salvador, BA – Brazil Mailing Address: Luis Correia • Escola Bahiana de Medicina e Saúde Pública – Av. Princesa Leopoldina, 19/402. Postal Code 40050-420, Salvador, BA – Brazil E-mail: lccorreia@cardiol.br Manuscript received November 13, 2018, revised manuscript May 20, 2019, accepted June 05, 2019 DOI: https://doi.org/10.36660/abc.20180345 Abstract Background: Plasma levels of brain natriuretic peptides have better diagnostic accuracy compared to clinical-radiologic judgment for acute heart failure. In acute coronary syndromes (ACS), the prognostic value of acute heart failure is incorporated into predictive models through Killip classification. It is not established whether NT-proBNP could increment prognostic prediction. Objective: To evaluate whether NT-proBNP, as a measure of left ventricular dysfunction, improves the in-hospital prognostic value of the GRACE score in ACS. Methods: Patients admitted due to acute chest pain, with electrocardiogram and/or troponin criteria for ACS were included in the study. The plasma level of NT-proBNP was measured at hospital admission and the primary endpoint was defined as cardiovascular death during hospitalization. P-value < 0.05 was considered as significant. Results: Among 352 patients studied, cardiovascular mortality was 4.8%. The predictive value of NT-proBNP for cardiovascular death was shown by a C-statistic of 0.78 (95% CI = 0.65–0.90). After adjustment for the GRACE model subtracted by Killip variable, NT-proBNP remained independently associated with cardiovascular death (p = 0.015). However, discrimination by the GRACE-BNP logistic model (C-statistics = 0.83; 95%CI = 0.69–0.97) was not superior to the traditional GRACE Score with Killip (C-statistic = 0.82; 95%CI = 0.68–0.97). The GRACE-BNP model did not provide improvement in the classification of patients to high risk by the GRACE Score (net reclassification index = – 0.15; p = 0.14). Conclusion: Despite the statistical association with cardiovascular death, there was no evidence that NT-proBNP increments the prognostic value of GRACE score in ACS. (Arq Bras Cardiol. 2020; 114(4):666-672) Keywords: Acute Coronary Syndrome; Heart Failure; Natriuretic Peptide, Brain; Mortality; Ventricular Dysfunction, Left; Biomarkers. Introduction Brain natriuretic peptide is a prohormone, biologically measured by its active fragment or its inactive terminal portion (NT-proBNP). These molecules are biomarkers of left ventricular dysfunction, released to the bloodstream by myocytes undergoing wall tension due to volumetric or pressure overload. 1 In the detection of heart failure, these peptides present better accuracy than clinical-radiological evaluation, being able to identify sub-clinical levels of decompensation. 2 The presence of left ventricular dysfunction is an important determinant of prognosis in patients with acute coronary syndromes (ACS). In this context, multivariate predictive models 3,4 take into account the presence of clinically manifested left ventricular dysfunction, well represented by the classification of Killip and Kimball. 5 Two reasons support the hypothesis that the use of plasma biomarkers may increase the prognostic value of these models: the capacity to numerically quantify the degree of cardiac decompensation and the higher sensitivity for subclinical changes, without impairing specificity. 2 In the context of ACS, the concentration of NT-proBNP has a well-documented prognostic accuracy. 6 However, from a predictive point of view, whether NT-proBNP has an incremental value in relation to probabilistic models that already contain Killip as a predictor variable is a controversial matter. 7-9 Among the models validated for risk prediction, GRACE score is the one with the best prognostic accuracy, containing Killip class as the marker of heart failure. 10-12 In this cohort, we tested the hypothesis that NT-proBNP incorporation increases the prognostic value of the GRACE score in patients with ACS. NT-proBNP was measured at admission and the primary outcome was defined as cardiovascular death during hospitalization. 666