Comparação de parâmetros da monitorização ambulatorial da pressão arterial em pacientes hipertensos com e sem doença renal crônica

Abstract

Systemic arterial hypertension (SAH) and chronic kidney disease (CKD) are two indissoluble clinical conditions; SAH is cause and consequence of CKD. Adequate blood pressure (BP) control can slow the progression of renal damage and diminish cardiovascular complications. Ambulatory Blood Pressure Monitoring (ABPM) has better accuracy than office blood pressure measurement and it can also report other prognostic factors. The main objective of this study was to describe ABPM parameters in hypertensive patients with CKD and compare with those with normal renal function. Patients with primary SAH, age between 40 and 75 years, were included and divided in two groups according to the presence (CKD =30 patients) or absence of CKD (without CKD = 30 patients), defined as a glomerular filtration rate < 60 ml/min (estimated by the MDRD equation). Patients were evaluated clinically and blood and urine samples were collected. ABPM for 24hours was performed and the following parameters analyzed: mean pressure, nocturnal blood pressure fall, morning surge, blood pressure variability, pulse pressure and ambulatorial arterial stiffness index. Data is shown as mean ± standard deviation (SD). Mean age was 63.2 ± 9.1 for CKD and 62.8 ± 9.3 years for the group without CKD. Mean office blood pressure was 144.6 ± 22.7 mmHg (systolic) and 85.3 ± 9.9 mmHg (diastolic) for CKD patients and 148.7 ± 18.3 mmHg (systolic) e 86.9 ± 8.7 mmHg (diastolic) for patients with normal renal function (p > 0.05). Albeit similar values for blood pressure were found in office and ABPM readings, the CKD group took more antihypertensive drugs (2.7 ± 1.1 versus 2.2 ± 0.6, p = 0.03). In CKD group, mean systolic nocturnal blood pressure fall was lower when compared with patients without CKD (3.8 ± 8.1% versus 7.3 ± 5.9%, p = 0.05). The ambulatorial arterial stiffness index (AASI) was significantly different between groups (0.45 ± 0.16 for CKD vs 0.37 ± 0.15 for those without CKD, p=0.04). Linear regression pointed AASI positively related to age (r=0.38, p<0.01) and pulse pressure (r=0.43, p<0.05) and inversely related to nocturnal blood pressure fall (r=-0.37, p<0.05). There was no correlation between AASI and estimated glomerular filtration rate. This was the first study to compare hypertensive patients with and without chronic kidney disease, with similar baseline characteristics, and showed that ABPM can report important parameters beyond blood pressure measurement, such as nocturnal blood pressure fall and AASI. Therefore, we suggest that hypertensive patients with CKD should be evaluated by ABPM in order to identify more parameters for cardiovascular risk stratification.