Níveis de metaloproteinase-9 e parâmetros hemodinâmicos centrais em diferentes níveis de pressão arterial

Abstract

Prehypertension predisposes individuals to systemic hypertension, which is the main risk factor for the development of cardiovascular diseases (CVD). Ambulatory blood pressure monitoring (ABPM) is an important method to assess blood pressure (BP) as it records levels during 24 hours, as well as changes related to the circadian cycle. In addition to peripheral hemodynamic parameters, 24h ABPM assesses central hemodynamic parameters, such as those linked to arterial stiffness. Thus, this examination presents several variables that correlate with cardiovascular events. Additionally, levels of metalloproteinase-9 (MMP-9), an enzyme involved in the degradation of extracellular matrix components, have been associated with the development of CVD and the arterial stiffness process. Objectives: The aims of the present study were: 1. to compare the peripheral and central hemodynamic variables obtained by ABPM at different BP levels according to the classification of normotension, prehypertension and arterial hypertension and to analyze MMP-9 values in these situations, correlating them with the variables obtained by ABPM. 2. To evaluate MMP-9 levels in acute BP elevations represented by hypertensive crisis. Methods: Participants included normotensive (NT), prehypertensive (PH) and controlled hypertensive (CHT) subjects. Individuals with hypertensive crisis, grouped as hypertensive urgency (HU) and hypertensive emergency (HE) were also included for MMP-9 measurement. Biochemical variables were evaluated for all volunteers. With the exception of hypertensive crisis, peripheral hemodynamic systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), pulse pressure, cardiac output (CO), peripheral vascular resistance (PVR) and central variables as central systolic BP (SBPc), central diastolic BP (DBPc), augmentation index 75% (AI75%) and pulse wave velocity (PWV) were assessed by 24h ABPM. Results: The PH group presented a significant difference when compared to CHT in relation to the peripheral (SBP) and central (SBPc and PWV) variables. There were also differences in these studies between the PH and NT for SBP, SBPc and DBPc. With ABPM, this study also identified significant differences in nocturnal systolic and diastolic dipping between PH and CHT. Regarding the MMP-9 levels, this study showed progressively higher levels between CHT, HU and HE, and that the PH group had higher MMP-9 levels than the CHT group. A positive correlation was identified between MMP-9 levels, CO and PVR. Conclusions: It is suggested that in the PH state there are changes in peripheral and central hemodynamic parameters and, consequently, in functional and structural alterations that predispose subjects to the development of systemic hypertension. Furthermore, MMP-9 levels appear to be influenced by antihypertensive therapy, since controlled hypertensive patients have lower MMP-9 levels than prehypertensive individuals. In the case of hypertensive crisis higher MMP-9 levels may constitute an important biomarker in the acute elevation of blood pressure.