Arquivos Brasileiros de Cardiologia (Dec 2012)
Níveis NT-Pro-BNP e resposta ao exercício em pacientes com fluxo lento coronariano NT-Pro-BNP levels and their response to exercise in patients with slow coronary flow
Abstract
FUNDAMENTO: Os peptídeos natriuréticos são liberados pelo coração em resposta ao estresse da parede. OBJETIVO: As concentrações de NT-Pro-BNP em pacientes com Fluxo Lento Coronariano (FLC) foram avaliadas antes e depois do teste de exercício e comparados com os valores dos controles saudáveis. MÉTODOS: A população do estudo foi de 34 pacientes com FLC [22 homens (64,7%), com idade 51,0 ± 6,2 anos], e 34 indivíduos normais com artérias coronarianas normais [21 homens (61,8%), com idade 53,2 ± 6,6 anos]. As taxas de fluxo coronariano dos pacientes e controles foram determinadas pelo escore TIMI Trombólise no Infarto do Miocárdio (Thrombolysis in Myocardial Infarction). As amostras de sangue foram coletadas em repouso e após o teste ergométrico. RESULTADOS: As concentrações basais de NT-Pro-BNP nos pacientes com FLC foram superiores às dos indivíduos-controle (NT-Pro-BNP: 49,7 ± 14,2 pg/mL vs. 25,3 ± 4,6 pg/mL p BACKGROUND: Natriuretic peptides are released by the heart in response to wall stress. OBJECTIVE: The NT-Pro-BNP concentrations in slow coronary flow (SCF) patients were assessed before and after the exercise test and compared with the values of healthy controls. METHODS: The study population was 34 patients with SCF [22 males (64.7%), aged 51.0±6.2 years], and 34 normal subjects with normal coronary arteries [21 males (61.8%), aged 53.2±6.6 years]. Coronary flow rates of all patients and control subjects were documented as Thrombolysis in Myocardial Infarction (TIMI) frame count. Blood samples were drawn at rest and after the exercise testing. RESULTS: The baseline NT-Pro-BNP concentrations of the SCF patients were higher than those of the control subjects (NT-Pro-BNP: 49.7±14.2 pg/mL vs. 25.3±4.6 pg/mL p<0.0001, respectively), and this difference increased after exercise test between the groups (NT-Pro-BNP: 69.5±18.6 pg/mL vs. 30.9±6.4 pg/mL p<0.0001). In SCF group after exercise, NT-Pro-BNP concentration in 15 patients with angina was higher than those without angina (76.8 ± 17.8 pg/mL vs. 63.8±17.5 pg/mL p=0.041). NT-Pro-BNP concentration in 11 patients with ST depression was also higher than those without ST depression (82.4 ± 17.3 pg/mL vs. 63.3 ± 16.1 pg/mL p=0.004). Median post-exercise increases in NT-Pro-BNP (Δ NT-Pro-BNP) were higher in the SCF group than in the control group (Δ NT-Pro-BNP: 19.8±7.7 pg/mL vs. 5.7±4.5 pg/mL p<0.0001). CONCLUSION: The results of this study suggest that there may be an important pathophysiologic link between the severity of SCF (microvascular or epicardial coronary artery dysfunction) and the level of circulating NT-Pro-BNP in SCF patients.
