ABC | Volume 110, Nº2, February 2018

Original Article Casali et al Short & very short-term blood pressure variability Arq Bras Cardiol. 2018; 110(2):157-165 Table 1 – Clinical characteristics of controls (C) and diabetic-hypertensive (DH) subjects. Variables Controls (n = 12) Diabetic-hypertensive (n = 51) p Age (years) 51.6 ± 4.4 57.3 ± 8.1 0.011 Male gender 6 (50.0) 11 (20.8) 0.065 BMI (Kg/m 2 ) 23.5 ± 2.3 30.5 ± 4.2 < 0.001 Office SBP (mmHg) 116.0 ± 8.2 139.2 ± 17.2 < 0.001 Office DBP (mmHg) 77.0 ± 5.0 80.9 ± 11.9 0.086 Duration of diabetes (years) - 6.9 (3.0-10.0) Fasting plasma glucose (mg/dL) - 156.5 ± 55.1 HbA1c (%) - 8.2 ± 2.0 Total cholesterol (mg/dl) - 181. 2 ± 32.6 HDL cholesterol (mg/dl) - 42.6 ± 13.2 Triglycerides (mg/dl) - 180.5 (132.8 – 248.5) Creatinine (mg/dl) - 0.82 ± 0.2 Microalbuminuria (> 17 µg/min) - 14 (27.4) BMI: body mass index, SBP: systolic blood pressure, DBP: diastolic blood pressure, HbA1c: glycated hemoglobin, HDL: high-density lipoprotein; FBPM: Short-Term Blood Pressure. Continuous variables are expressed as mean ± standard deviation or median and interquartile range (p25-p75) and percentiles. Categorical variables are expressed as number (%). Comparisons were tested by Pearson’s χ2 test and Student’s t test. bands 21 and expressed spontaneous baroreflex sensitivity. All series were analyzed by a trained researcher who was also blinded to conditions and subjects. Delta indices were calculated for HR variability (HRV), LF/HF index and LF component of BPV, using variable values before (rest) and after standing-up maneuver (sympathetic activation, SA) for normalization, as follows: Delta = SA – REST REST These indices had been previously proposed in order to quantify autonomic responses to standing-up maneuver. 22,23 Biochemical measurements Venous blood samples for biochemical measurements were drawn after 12-hour fasting. Plasma glucose was determined by the glucose oxidase method, serum creatinine by Jaffé’s reaction, and glycated hemoglobin (HbA1c) by ion-exchange HPLC (Merck-Hitachi L-9100 HbA 1c analyzer; Merck, Darmstadt, Germany). Serum cholesterol and triglycerides were measured by enzymatic-colorimetric methods (Merck Diagnostica, Darmstadt, Germany; Boehringer Mannheim, Buenos Aires, Argentina), and HDL cholesterol by a homogeneous direct method (autoanalyzer, ADVIA 1650). Low-density lipoprotein (LDL) cholesterol was calculated using Friedewald’s formula. 24 Statistical analyses Data are expressed as mean ± standard deviation (SD) or medians and interquartile intervals, according to normality plots with tests and percentages. Pearson’s chi-square, unpaired Student’s t-test, Mann-Whitney rank sum test, two-way repeated measures ANOVA or Friedman repeated measures analysis of variance on rank, post hoc Student‑Newman‑Keuls were used when variables were compared between groups, as indicated. The correlation between the different indices obtained by 24h-ABPM and by FBPM were analyzed by the Spearman’s correlation coefficient. Correlations were considered for discussion only if they were statistically significant and represented large-effect sizes, as defined by a correlation coefficient of 0.50 or higher. 25 All statistical analyses were performed using the SPSS statistical software package version 17.0 for Windows (SPSS Inc., Chicago, IL, USA). Statistical significance was set at p < 0.05. Results Twelve healthy subjects (C) and 73 diabetic-hypertensive patients (DH) were selected; all C and 51DHhad complete data from 24h-ABPM and FBPM. Controls were 51.7 ± 8.1 years old and 50% were men; DH were 57.3 ± 8.1 years-old, 12% were men, 54.9% had their office BP well-controlled (< 130/80 mmHg) and 35.8% had good metabolic control (HbA1c < 7.0%). Clinical characteristics are shown in Table 1. Short-term BP variability (24h-ABPM) results are displayed in Figure 1. There were differences among the indices obtained from total, daytime, and nighttime periods for both C and DH groups, confirming the expected circadian variations and justifying the division into periods. Comparisons between C and DH groups are represented by the bar graph, which shows that higher SBP and time-rate obtained from SBP in DH group for all periods evaluated. The mean of the standard deviation and the coefficient of variation of 24-hour SBP were different between C and DH in daytime only. Circadian behavior differences, calculated by subtracting nighttime from daytime values, show a lower reduction of mean SBP at night in DH patients as compared to controls. The differences obtained for 159