Ambulatory blood pressure monitoring in essential hypertensive patients with acute ischaemic stroke

Blood pressure (BP) has been identifi ed as a risk factor for various health disorders, including stroke onsets. Hypertension is one of the crucial health problem among adult Ukrainian. Due to the importance of elevated BP in stroke causality, BP measurement remains critical. However, it is limited information about value in clinical practice of ambulatory blood pressure monitoring (ABPM) data in hypertensive patients with inadequately controlled BP with acute stroke compared with those individuals who has no vascular onset. The aim of the study was to determine ABPM parameters in essential hypertensive patients with ischaemic hemisphere stroke. Materials and methods. A total of 114 study participants were analyzed (mean age 62 (56;72) years, 40 % women). We divided them into two groups according to the level of 24-h systolic BP (SBP) and diastolic BP (DBP), and the results of clinical examination. The fi rst group (n=83) were inadequately controlled essential hypertensive individuals with high systolic or/and diastolic BP level according to the ABMP results, and the second one (n=31) were EH patients with an acute hemispheric ischaemic stroke (IS). Diagnosis of stroke was confi rmed with clinical examination and computed tomography scan or magnetic resonance imaging results, and ABPM was conducted in 4.2±2.3 days after the stroke onset. Results. We had statistician difference (p<0.001) between groups of such parameters, as average SBP (diurnal, daytime, nighttime); diurnal pulse BP; SBP load (p<0.05); the diurnal AASI (p<0.05); circadian rhythm of DBP (p<0.05). No differences were found between the groups in morning surge calculated as speed and amplitude of the BP climbed in morning hours both for SBP (P=0.422 and P=0.395 respectively) and DBP (P=0.860 and P=0.337 respectively). Conclusion. In the present study, we evaluated the ABPM parameters in inadequately controlled essential hypertensive individuals with and without acute ischaemic hemispheric stroke. There was no statistical difference in ABPM parameters as for diastolic BP (averages, BP load) and for systolic BP (some parameters of BP load, variability). Meanwhile, there was statistician difference in systolic BP profi le (averages, BP load, and the circadian index), pulse BP and the diurnal AASI. Zaporozhye medical journal 2016; No6 (99): 25–29


Запорожский медицинский журнал. -2016. -№6 (99). -С. 25-29
H ypertension is one of the crucial health problem among adult Ukrainian population affecting 55.8 % [1].Blood pressure (BP) has been identifi ed as a risk factor for various health disorders, including stroke onsets, approximately a half of which are attributed to high BP [12].It was shown that the benefi t of BP reduction on stroke incidence or recurrence, population attributable risk calculations place hypertension as the single factor explaining the highest percentage of stroke risk [18].Furthermore, hypertension can infl uence to the high level of stroke mortality and a high frequency of disability [3].
Due to the importance of elevated BP in stroke causality, BP measurement remains critical.The ambulatory blood pressure monitoring (ABPM) is a modern method due to international and local recommendations for investigation of hypertension [2,17].Use of the ABPM to determine the presence of raised BP is becoming standard practice in developed countries [18].Noticeably, it has been reported that ABPM is superior predictor of future cardiovascular events than clinic BP measurement [5].However, it is limited information about value in clinical practice of ABPM data in hypertensive patients with inadequately controlled BP with acute stroke compared with those individuals who has no vascular onset.
In the present study, we sought the confi rmation that hypertensive patients with acute hemisphere ischaemic stroke (IS) would have a considerable difference in the ABPM parameters compared with inadequately controlled essential hypertensives (EHs).
For this purpose, we measured ABPM data in inadequately controlled EH individuals with or without acute hemisphere ischaemic stroke.

Materials and methods
The study protocol was approved by the Medical ethics committee of the Zaporizhzhia State Medical University, and the study was conducted according to the Helsinki Declaration.We examined patients admitted to the Zaporizhzhia clinical hospital № 6 (stroke, cardiology, intensive care units), which is the city stroke center and also the clinical base of the Department of Propedeutics of Internal Diseases, Zaporizhzhia State Medical University (the chief of the Department V. V. Syvolap).A researcher provided written and oral information on the study before the examination.Information on demographics and clinical characteristics was extracted from patients' medical records and purpose-designed questions in the questionnaire.The measurement of brachial BP has been performed using aneroid-type sphygmomanometer and a health professional auscultating the Korotkoff sounds.All the patients underwent ABPM.
ABPM was recorded using a bifunctional device (Incart, S.-P., R. F.).After the baseline examination participants were fi tted with it on their nondominant arm if there were no considerable difference of BP results.Appropriate cuff bladder size was determined based on arm circumference.BP was measured at 15-min intervals from 07:01 to 23:00 and at 30-min intervals from 23:01 to 07:00.For analyzing matter, we defi ned awake and asleep periods as the fi xed periods of time (from midnight to 06:00 AM for nighttime and from nighttime to 06:00 AM, respectively).Analysis was carried out using an oscillometric method.Moreover, we categorized patients based on night/day ratio [10] separately for SBP and DBP as (1) rising or absence of dipping (ratio >1.0); (2) mild dipping (0.9< ratio ≤1.0); (3) dipping (0.8< ratio ≤0.9); and (4) extreme dipping (ratio ≤0.8).
Quality of the ABPM studies was defi ned by the length of time that the monitor was actually worn (≥21 hours) and the number of successful BP recordings (≥1 valid BP measured per two hours were acceptable for analysis, so that there were 14 measures for daytime and at least 7 measurements -for nighttime period) [10].Upon completion of the 24-h ABP recording, the data was downloaded and analyzed statistically to calculate BP averages for systolic BP (SBP) and diastolic BP (DBP) for different time periods (i.e., 24-h, daytime and nighttime) as well as BP loads, BP variations and ABPM indexes and coeffi cients.In particularly, the BP load was calculated as the proportion of BP ≥135/85 mm Hg during the day period and BP ≥120/75 mm Hg during the night period [17,18].And the BP variability was calculated manually as standard deviation of SBP and DBP over a 24-h period, daytime and night periods for each patient [18].The AASI was calculated manually as one minus diastolic (DBP) versus systolic blood pressure (SBP); the Sym_Slope was calculated as slope SBP-versus-DBP divided by correlation coeffi cient (r); the Sym_AASI was founded as 1-1(1-AASI)/r in linear regression analysis as described [9,16].
Statistical analysis was performed using the Statistica version 6.0 (StatSoft, Tulsa, OK., U.S.A.).The various BP values and relationships between them were compared and calculated after excluding patients with inadequately controlled BP.The Shapiro-Wilk test was used to test for deviation from normality.Categorical data are presented as percentages and continuous data as mean ± standard deviation or medians and interquartile ranges as appropriate after testing for normality of distribution.Comparisons between groups were done using the Student t, the Mann-Whitney U and χ 2 tests as appropriate.Two-tailed P values <0.05 were considered statistically signifi cant.

Results and its discussion
In fl ow chart (Fig. 1), it is presented the stages of patients including to the analysis.We enrolled individuals older 18 years with previously documented EH, with sinus rhythm on electrocardiogram (ECG) monitoring, with valid ABPM results.
The study population reported here includes 114 patients, the median age of study population was 62 (56; 72) years and 40 % were female.We classifi ed the subjects into two groups according to the results of clinical examination and ABPM results.The fi rst group (n=83) were inadequately controlled essential hypertensive individuals with high systolic or/and diastolic BP level according to the ABMP results and the second one (n=31) were EH patients with an acute hemispheric IS, diagnosis confi rmed with clinical examination and computed tomography scan or magnetic resonance imaging results, and ABPM was conducted in 4.2±2.3days after the stroke onset.
Age and sex did not differ between the groups of EHs and EH individuals with IS (P=0.110 and P=0.931, respectively).There was a steady increase in the overwhelming ABPM parameters.Particularly, the averages SBP 24-hour and DBP 24-hour were elevated in all hypertensive patients, however, only for SBP 24-hour there were statistical difference (P<0.001) as it is seen in Table 1.
The results of the analysis also show that groups were signifi cantly different only in averages of SBP and pulse BP (PBP).Diastolic BP averages were not shown signifi cantly different between groups.There were increased results in IS group for diurnal SBP (P<0.001),daytime SBP (P<0.001) and nighttime SBP (p<0.001) as compared with the group of EH participants without IS.In addition, for diurnal PBP, results obtained in IS patients were signifi cantly greater than obtained in inadequately controlled BP patients (P<0.001).
It was demonstrated statistical difference in BP loads only for SBP parameters.Percentage of BP augmentation for the diurnal period and daytime periods was considerably higher in the second group with IS (P<0.001 and P=0.001, respectively).Also, the square normalized indexes (SBP Nsq ) of hypertension for all periods (for diurnal, daytime and nighttime) were more in IS patients group compared with the other group of EH individuals (84.6 %, 76.9 %, 93.8 % respectively) with signifi cant difference between two groups (P˂0.05).Both the square indexes (SBP Sq ) of hypertension (for diurnal and nighttime periods) and the time index of hypertension (for diurnal period and daytime) were 94.2 %, 16.9 % and 26.7 %, 28.8 % increased respectively and showed signifi cant difference between groups (P˂0.05).
At the same time, only DBP data for nighttime period achieved signifi cance (P<0.001) after analysis of SBP and DBP variability.
Notably, only the AASI for 24-h period and the AASI for nighttime period were signifi cantly higher in IS individuals (P=0.016 and P˂0.015 respectively).Meanwhile, there was no statistical difference in other new calculated ABPM indexes between groups (Sym_AASI 24 , (P=0.068);Sym_slope 24 , (P=0.068)).
The groups were statistically different only in DBP data concerning analysis of circadian indexes (Table 2).Particularly, there were substantially more mild dipping in DBP pattern in participants with IS as compered with the other group of EHs (39 % vs. 19 %; P<0.029).
No differences were found between the groups in morning surge calculated as speed and amplitude of the BP raising in morning hours both for SBP (P=0.422 and P=0.395 respectively) and DBP (P=0.860 and P=0.337 respectively).
Discussion BP tends to remain high in the hours and days after acute stroke.It was found that BP elevated in 84 % of patients in the acute phase of stroke [11].BP levels are closely associated with clinical outcome in individuals with acute IS [13].As noted in a

Whole study population (n=247)
EXCLUDED (after analyzing clinical information): -not sinus rhythm on ECG monitoring (n=6) -not IS (n=10) -not previous EH (n=21) EXCLUDED (after ABPM analysis): -not valid ABPM (n=42) -ABPM less 130/80 mm Hg (n=55) Patients included in the analysis (n=113) Skalidi et al. study [7] increased SBP values are associated with formation of brain edema.Both stroke-specifi c and non -specifi c external stimuli as well as other transient factors may contribute to BP changes in participants with acute stroke.However, it is noticeably, that BP recorded during sleep or in the early morning is more predictive of fi rst or recurring stroke events than daytime SBP, especially in the elderly [9].Observational studies show that both extremely high and extremely low BP on admission correlates with death or dependency in acute stroke participants [11].Recently, in a cohort study it was found that both daytime and nighttime BP predicted all cardiovascular events in general population.However, nighttime BP, adjusted for daytime BP independently predicted mortality (total, cardiovascular, and non-cardiovascular) [14].
It was also demonstrated that BP load is an independent predictor of hypertensive target organ damage and adverse cardiovascular risk profi le according to the study results, where subjects with a higher SBP load, adjusted for average diurnal SBP, were found to have increased relative myocardial wall thickness and total peripheral vascular resistance [15].
A recent study in stroke cohort population showed the loss of nocturnal BP dipping [9], which may lead to worse target organ damage and facilitates recurrent stroke.Modest preservation of nocturnal BP dipping and the physiological circadian BP pattern may induce a protective effect on cerebral circulation in IS patients.
Several longitudinal epidemiological studies have shown the predictive value of arterial stiffness as intermediate end point, i.e. the greater the arterial stiffness, the greater the number  ISSN 2306-4145 of cardiovascular events [11] and found as one of the strong predictor of stroke and cardiovascular mortality [4].Recently, in meta-analysis it was concluded that this index predicts independently future clinical events, particularly stroke onset [6].
Increased arterial stiffness is associated with higher cardiovascular risk, and carotid stiffness was shown to be a predictor of incident stroke, independent of other cardiovascular risk factors and of aortic stiffness as estimated by carotid-femoral pulse wave velocity [8].
A number of clinical studies propose prognostic value of ABPM parameters as the result of population studies, however, it is not clear the additional value of ABPM data in individuals who are on the acute phase of cardiovascular (CV) event or have already infl uenced by CV events, like stroke, for the clinical situation.Conclusions 1. Overall, in the present study we have found statistical difference in all groups of ABPM parameters, as recommended by the European guidelines as new ones, like the AASI.Noticeably, none of the average and load for diastolic BP parameters, and variability and the circadian index for systolic BP is shown statistical difference between the groups.Meanwhile, there was statistical difference in systolic BP profi le (averages, BP load, the circadian index), pulse BP and the AASI.However, the new described indexes of ABPM not show difference in the groups, except the AASI.
2. Future studies should provide ABPM data on a wider range of populations and diseases, as well as consensus of reference values.
Confl icts of interest: author have no confl icts of interest to declare.