Função endotelial vascular em pacientes com fluxo coronário lento e os efeitos do nebivolol Vascular endothelial function in patients with coronary slow flow and the effects of nebivolol

FUNDAMENTO: A função endotelial braquial tem sido associada ao fluxo lento coronário (FLC). O aumento do fluxo sanguíneo para a artéria braquial faz com que o endotélio libere óxido nítrico (ON), com subsequente vasodilatação. Além de sua atividade com betabloqueador, o nebivolol provoca vasodilatação, aumentando a liberação endotelial de ON. OBJETIVO: Avaliar os efeitos do nebivolol na função endotelial vascular em pacientes com FLC. MÉTODOS: 46 pacientes com FLC e 23 indivíduos com artérias coronárias epicárdicas normais foram examinados com ecocardiografia transtorácica e ultrassonografia da artéria braquial. Os pacientes foram reavaliados dois meses após o tratamento com aspirina ou aspirina e nebivolol. RESULTADOS: Os pacientes com FLC apresentaram maior índice de massa corporal (26,5 ± 3,3 vs. 23,8 ± 2,8, p < 0,001), tempo de relaxamento isovolumétrico (TRIV) de influxo mitral (114,9 ± 18,0 vs. 95,0 ± 22,0 mseg, p < 0,001), menor fração de ejeção do ventrículo esquerdo (FEVE) (63,5 ± 3,1% vs. 65,4 ± 2,2, p = 0,009), colesterol HDL (39,4 ± 8,5 vs. 45,8 ± 7,7 mg/dL, p = 0,003) e dilatação fluxo-mediada da artéria braquial (DFM) (6,1 ± 3,9% vs. 17,6 ± 4,5%, p BACKGROUND: Brachial endothelial function has been associated with coronary slow flow (CSF). Increasing blood flow to brachial artery provokes endothelium to release nitric oxide (NO) with subsequent vasodilatation. Besides its β1-blocker activity, nebivolol causes vasodilatation by increasing endothelial NO release. OBJECTIVE: To assess the effects of nebivolol on vascular endothelial function in patients with CSF. METHODS: Forty-six patients with CSF and 23 individuals with normal epicardial coronary arteries were examined with transthoracic echocardiography and brachial artery ultrasonography. The patients were reevaluated two months after treatment with aspirin or aspirin plus nebivolol. RESULTS: Patients with CSF had higher body mass index (26.5 ± 3.3 vs. 23.8 ± 2.8, p < 0.001), mitral inflow isovolumetric relaxation time (IVRT) (114.9 ± 18.0 vs. 95.0 ± 22.0 msec, p < 0.001) and lower left ventricular ejection fraction (LVEF) (63.5 ± 3.1% vs. 65.4 ± 2.2, p = 0.009), HDL-cholesterol (39.4 ± 8.5 vs. 45.8 ± 7.7 mg/dL, p = 0.003) and brachial flow-mediated dilatation (FMD) (6.1 ± 3.9% vs. 17.6 ± 4.5%, p < 0.001). There were significant correlations between FMD and the presence of CSF (r = 0.800, p < 0.001) and HDL-cholesterol (r = 0.349, p = 0.003). Among Patients with CSF, although pretreatment mean FMD values were similar (6.1 ± 4.3% vs. 6.0 ± ,6%, p = 0.917) compared to aspirin alone group, posttreatment FMD was significantly higher in patients treated with aspirin plus nebivolol (6.0 ± 3.5% vs. 8.0 ± 2.9%, p = 0.047). Treatment with nebivolol was associated with a significant increase in FMD (6.0 ± 3.6 to 8.0 ± 2.9 %, p = 0.030) whereas treatment with aspirin alone was not. CONCLUSION: Endothelial function may be impaired in both coronary and brachial arteries in patients with CSF and nebivolol may be effective in the improvement of endothelial function in patients with CSF.