Is ambulatory blood pressure monitoring reliable in hypertensive patients with atrial fibrillation?]

Atrial fibrillation (AF) is commonly seen in patients (pts) with systemic hypertension. They are usually excluded from ambulatory blood pressure monitoring (ABPM) because its accuracy is unknown. The aim of our study was to determine if ABPM can be used to assess 24 hour BP in pts with AF. We included hypertensive pts with chronic (> 6 months) AF, controlled heart rate (60-100 c.p.m), under therapy and also hypertensive pts in sinus rhythm (control group--CG). They were submitted to 24 hour ABPM (Spacelabs 90207). Manual BP with a standard mercury sphygmomanometer was taken during 3 visits (office BP) and on the day of ambulatory monitoring. Simultaneous measurements with a T-Tube were also performed. Thirty pts with chronic AF (63% males), mean age 73 +/- 8 years (52-85) and 18 pts in sinus rhythm (CG) were studied. The age, gender, office BP, ambulatory BP and proportion of successful measurements was similar in the 2 groups. In CG systolic and diastolic office BP did not differ from day ambulatory BP (148 +/- 14/84 +/- 7 vs 138 +/- 18/76 +/- 11 mmHg) and the same was seen in pts in AF (table). In this group, only the systolic BP taken immediately before the ambulatory device was put on, was significantly different from day ambulatory BP (148 +/- 21 vs 137 +/- 19 mmHg, p = 0.04). The proportion of successful measurements in AF group was 94 +/- 8 (65-98) with 93% > 80%. In 64 simultaneous measurements the differences were 6 +/- 5 and 5 +/- 5 mmHg for systolic and diastolic BP. Casual and ambulatory heart rate was also similar in the two groups (76 +/- 7/76 +/- 12--AF group; 78 +/- 10/78 +/- 8--control group). In conclusion, this study demonstrates that ABPM can be used to assess BP in patients with atrial fibrillation. There was a high percentage of successful recordings (93%). As in patients in sinus rhythm, there was no significantly difference in mean office blood pressure and daytime ambulatory blood pressure.     

Twenty-four-hour ambulatory blood pressure in shift workers

Blood pressure and heart rate of 15 male shift workers were measured every 15 minutes for 24 hours during three work shifts: morning, 4:00 AM to noon; afternoon, noon to 8:00 PM; and night, 8:00 PM to 4:00 AM. For each shift, 24-hour systolic and diastolic blood pressure showed a large "trough" (the low pressure span) and a continuous range of elevated pressure (the high pressure span). Fourier series were used to model the 24-hour blood pressure profiles. A careful examination of the residuals (measured minus predicted pressures) showed that four harmonics were necessary to describe the data accurately. The model enabled localization in each blood pressure profile of the high and low pressure spans that did not coincide with the subject's work and rest periods. The time and slope of blood pressure entering and leaving these spans could also be individually determined. Mean blood pressure during the high pressure span was the same for the three shifts, but mean blood pressure during the low pressure span was lower when the subject worked in the afternoon. During that shift, the systolic blood pressure slopes entering and leaving the low pressure span were steeper than during the two other shifts. The high pressure span was longest during the night shift and shortest during the afternoon shift. Therefore, a change in the working time profoundly perturbed the 24-hour blood pressure profile.(ABSTRACT TRUNCATED AT 250 WORDS)     

120例房颤患者24h动态心电图分析

目的：分析房颤患者12导联动态心电图,探讨其伴发的异常表现与年龄、疾病诊断情况及心脏器质性病变的关系,进一步认识阵发性房颤。方法收集我院动态心电图检测诊断为房颤（AF）及阵发性房颤（PAF）的120例患者的动态心电图,采用回顾性分析方法,根据动态心电图记录房颤中伴发的异常表现,结合临床资料进行分析和总结。结果①120例房颤患者中,动态心电图检测显示68例伴发有不同类型的心电图异常,异常发生率为68／120（56．7％）,其中以快速心室率及室性早搏最多见,分别占37／120（30．8％）和35／120（29．2％）,其次分别为：ST-T 改变占32／120（26．7％）;传导阻滞占29／120（24．2％）;＞2．0 s 的长 R-R 间期占23／120（19．2％）和室性心动过速7／120（4．2％）。在65岁以上的房颤患者中,心电图伴发的异常表现在同一患者有时可达两种或两种以上。②120例房颤患者中阵发性房颤有18例,占15％（18／120）,多由房性早搏触发所致。肺心病组、冠心病组、外科检查组和风心病组都以室性早搏最多见,分别占45％（5／11）、50．0％（11／22）、42．9％（2／7）和30．0％（3／10）;高血压组以ST-T 改变最多见,占44．1％（15／34）;胸闷、心悸组、甲亢组及糖尿病组都以快速心室率最多见,分别占38．0％（8／21）、33．3％（1／3）和22．2％（2／9）;晕厥组中1例伴发快速心室率,1例伴发＞2．0 s 的长 R-R 间期。有器质性心脏病房颤患者动态心电图伴发异常表现率可高达67．4％。结论动态心电图可准确显示房颤患者伴发的心电图异常表现,在合并器质性心脏病和／或65岁以上的房颤患者中有时达两种甚至更多,可确定阵发性房颤的心电始动因素及其部位。     

Twenty-four-hour ambulatory blood pressure monitoring in the evaluation of antihypertensive drugs: methodological aspects

Ambulatory blood pressure monitoring (ABPM) provides reproducible measurements over 24 h, avoiding the alerting reaction. However, the reproducibility of mean hourly ambulatory values is poorer by far than the whole day average. In phases II and III clinical triams ABPM seems to evaluate the time-course of the antihypertensive effect and helps to determine the trough: peak ratio. The potential advantage of the method could be an increase in statistical power of the trial, with regard to the number of patients to include, according to the study design. ABPM led to the identification of 'white-coat' hypertension with elevated clinic blood pressure measurements and persistently normal ABPM over time. No epidemiological evidence to include patients in trials according to ABPM criteria has been provided to date, but a subsequent stratification on the initial ABPM data has to be performed. Although an insignificant effect on the 24 h mean blood pressure values in short-term trials, the use of placebo seems to be necessary to supply reference blood pressure values for dosing and trough: peak ratio determination. Whether ABPM is able to decrease the number of patients to include remains debated. It has been noted that an increasing number of readings could lead to a decrease in SD and that a decrease in the number of patients required can be expected both in parallel and in cross-over design trials. However, it has been reported that the advantage of the higher reproducibility of ABPM could be lost in parallel design trials and that analysis of the antihypertensive effect of the drug throughout the 24 h could then require more patients. In order to conduct multicentre trials using ABPM, a consensus among investigators is needed for the presentation and analysis of the results. We have to overcome these difficulties in order to avoid a 'centre effect' and to allow for the expected increase in power of the trial. In such a trial the comparability of parallel groups could be jeopardized by a misadherence to the ABPM protocol. How can ABPM modify the doctor-patient relationship?. A pedagogical approach seems necessary, namely to inform the patients concerning technical and medical prerequisites of the method, in order to conform to the 'guidelines'. ABPM might constitute a new determinant of compliance with treatment; but its influence, beneficial or not, remains to be assessed. Compliance evaluation could be combined with ABPM, in order to provide a better evaluation of the antihypertensive effect of the drugs.     

Twenty-four-hour ambulatory blood pressure in children with sleep-disordered breathing

Obstructive sleep apnea causes intermittent elevation of systemic blood pressure (BP) during sleep. To determine whether obstructive apnea in children has a tonic effect on diurnal BP, 24-hour ambulatory blood pressure was obtained from 60 children with mean age of 10.8 +/- 3.5 years. Thirty-nine children had obstructive apnea and 21 had primary snoring. Children with obstructive apnea had significantly greater mean BP variability during wakefulness and sleep, a higher night-to-day systolic BP, and a smaller nocturnal dipping of mean BP. Variability of mean arterial pressure during wakefulness was predicted by the desaturation, body mass, and arousal indices, whereas variability during sleep was predicted by apnea-hypopnea and body mass indices. Nocturnal BP dipping was predicted by the desaturation index. There were no significant differences in systolic, diastolic, or mean arterial BP during sleep between the groups. Diastolic BP during wakefulness was significantly different between the groups and correlated negatively with apnea-hypopnea index. We conclude that obstructive apnea in children is associated with 24-hour BP dysregulation and that, independent of obesity, the frequency of obstructive apnea, oxygen desaturation, and arousal contributes to abnormal BP control.     

Twenty-four-hour blood pressure monitoring and effects of indapamide

Twenty-four-hour blood pressure (BP) monitoring with a noninvasive device (Kontron) has been used to assess the effect of a single dose of indapamide in a group of patients with essential hypertension. Originally 23 patients were selected. Three patients withdrew from the study because of refusal to go through the second 24-hour recording. Eight of the remaining patients had to be excluded for technical reasons, which left 12 patients available for analysis. All patients received a single dose of indapamide, 2.5 mg/day. Before treatment began, a 24-hour BP control was performed, and a second one a month later (37 +/- 8 days). The age of the patients was 46 +/- 10 years. Diurnal BP (8 am to 10 pm) and heart rate were, respectively, 148 +/- 15/101 +/- 6 mmHg and 79 +/- 9 beats/min; night BP (10 pm to 8 am) was 131 +/- 15/88 +/- 7 mmHg and heart rate 71 +/- 10 beats/min. After therapy, diurnal BP was 131 +/- 15/92 +/- 7 mmHg (-15 +/- 7/-8 +/- 4: p less than 0.0001/p less than 0.0001); heart rate 82 +/- 8 beats/min (difference not significant); night BP was 115 +/- 13/80 +/- 8 mmHg (-16 +/- 11/-8 +/- 7: p less than 0.0001/p less than 0.0001) and heart rate 70 +/- 9 beats/min (difference not significant). Twenty-four-hour systolic work values were 106 +/- 15 at the beginning of the trial and 96 +/- 14 (-9.7 +/- 14; p less than 0.05) after 1 month of indapamide treatment. Variability did not change with treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reproducibility of ambulatory blood pressure monitoring

Short-term blood pressure variability has been studied extensively with monitoring techniques. To assess whether or not and to what extent average 24-hour blood pressure varies when repeatedly recorded, 12 mild to moderate hypertensive subjects underwent 3 non-invasive blood pressure monitorings at monthly intervals. When the average 24-hour blood pressure of the whole group was evaluated no substantial differences were found between the 3 recordings, even though slightly lower blood pressure values were recorded at the first monitoring. However, when the within-period comparison was studied in the single patients, remarkable discrepancies of up to 20.9/15.8 mmHg were detected. Systolic and diastolic blood pressure variations greater than or equal to 5 mmHg were recorded in 58% of the subjects. These differences were unrelated to the number of faulty readings. Casual blood pressure varied even to a greater extent between the first and the subsequent visits; no correlation was found between casual and 24-hour blood pressure variations. The results of the present study indicate that ambulatory blood pressure may vary even to a great extent when repeatedly recorded. This finding entails important clinical implications, as the evaluation of the hypertensive patient is usually made with a single blood pressure monitoring.     

Sex differences in ambulatory blood pressure monitoring

Purpose

Referral to ambulatory blood pressure monitoring may have bearing upon blood pressure control and prognosis. We describe sex-related differences in referral for ambulatory monitoring and their prognostic impact.

Methods

Between 1991 and 2005, 3957 patients were monitored in our ambulatory monitoring service, of whom 2114 (53%) were women. Demographic and clinical data were analyzed according to sex.

Results

Age (58 ± 15 vs 52 ± 17 years, respectively) and body mass index (27.5 ± 4.9 vs 26.9 ± 4.0 kg/m², respectively) were higher in women than men. Treatment for hypertension was more prevalent in women (62% vs 53%, respectively). Clinic systolic blood pressure (148 ± 24 vs 146 ± 20 mm Hg, respectively) and clinic pulse pressure (65 ± 22 vs 59 ± 18 mm Hg, respectively) were higher in women compared with men. In women, the white-coat effect was increased, compared with men; 5.2 ± 12.4% vs 1.5 ± 10.7% systolic, and 5.4 ± 11.2% vs 3.6 ± 10.3% diastolic. Consequently, women had lower ambulatory blood pressure than men. In women, 24-hour blood pressure was 136 ± 17/76 ± 10 vs 140 ± 15/81 ± 10 mm Hg in men, awake blood pressure 141 ± 17/80 ± 11 vs 144 ± 15/84 ± 10 mm Hg, and sleep blood pressure was 125 ± 19/67 ± 10 vs 127 ± 18/71 ± 11 mm Hg. Age-adjusted ambulatory blood pressure also was lower in women. Ambulatory heart rate was higher in women (P <.0001). Kaplan-Meier survival did not differ by sex (P = .66), despite older age and higher clinic blood pressure.

Conclusions

The results might imply that referral was driven by the physicians' overall patient risk perception. The greater magnitude of white-coat effect in women, and correspondingly lower ambulatory blood pressure, might in part account for similar mortality in the face of older age and higher clinic blood pressure.     

Reproducibility of ambulatory blood pressure monitoring

OBJECTIVE: To investigate whether blood pressure monitoring is reproducible. DESIGN: Reproducibility of ambulatory blood pressure monitoring data was assessed by means of traditional and relatively new statistical methods, namely correlation coefficients, regression analysis and agreement analysis. METHODS: Ninety-one normotensive and hypertensive, uncomplicated outpatients underwent monitoring twice (mean interval 241 days). Data were analysed for reproducibility, correlation, difference and adaptation. Analyses were performed to verify the reproducibilities of the diagnosis of hypertension and of the treatment assessment. RESULTS: Ambulatory blood pressure monitoring is highly reproducible in terms of traditional statistics, but not in terms of the agreement analysis (error as high as 18 mmHg), although it performs better than does office sphygmomanometry (error as high as 38 mmHg). Reproducibility is acceptable in normotensive subjects and in patients who respond to treatment, but untreated hypertensives and those who do not respond to treatment show a worse ratio. CONCLUSION: The reproducibility of ambulatory blood pressure monitoring requires improvement. We do not know how many repeated measurements we need before diagnosing hypertension. Spontaneous variability of blood pressure interferes with blood pressure reproducibility. Diagnosis and treatment assessment in hypertension must take into account poor reproducibility.     

Epidemiology of ambulatory blood pressure monitoring

An operational threshold for making clinical decisions on the basis of ambulatory blood pressure monitoring must be defined [1-3]. This requires that the relationship between the ambulatory blood pressure and the incidence of cardiovascular complications be clarified beyond present understanding [4-7]. In addition, the distribution of the ambulatory blood pressure must be characterized better under various conditions and for various populations and compared with the centrality and spread of the conventional blood pressure under similar circumstances.     

24-hour ambulatory blood pressure monitoring

24-hour ambulatory blood pressure monitoring (ABPM) is the exact, fully automatic and noninvasive method for evaluation of the 24-hour hemodynamic profile of the subject by multiple and regular blood pressure and heart rate measurement. In comparison with causal blood pressure measurement, ABPM allows the definition of daytime and nighttime blood pressure averages, diurnal changes of blood pressure, localization of periods of the most frequent appearance of hypertensive values, specification of hypertensive load, percent time elevation and diagnosing of white coat phenomenon. The use of all mentioned findings leads to the improvement of blood pressure control in patients with resistant hypertension, polymorbidity, helps to analyze paroxysmal hypertension, verify diagnosis of the hypertension in patients with borderline or high normal blood pressure. The final profit is the reduction of the target organ damage and reduction of cardiovascular morbidity and mortality. Definite diagnosis of the white coat phenomenon markedly decreases consumption of the antihypertensive drugs. In addition, this method enables better evaluation of hypotensive syndromes and is very helpful in the investigation of physiology of blood pressure regulation, biorhythms and in pharmacodynamical studies of the new antihypertensives.     

Reliability of ambulatory blood pressure monitoring

OBJECTIVE: To focus on the reliability of ambulatory blood pressure monitoring and on its limitations in clinical practice, and to construct adequate strategies to improve ambulatory monitoring performance. METHODS: The literature was reviewed, and personal data were used. DISCUSSION: Since the beginning of non-invasive ambulatory blood pressure monitoring, it appeared that some subjects had a high proportion of outlying readings that were unlikely to be accurate. Although ambulatory blood pressure is more reproducible than clinic blood pressure, large day-to-day differences have also been reported in reproducibility studies for average 24 h blood pressure. It has been shown that, for day-to-day 24 h blood pressure differences greater than 4/3 mmHg, ambulatory blood pressure is poorly predictive of the degree of target organ damage. The variability of average 24 h blood pressure may arise from several causes, including true biological variability, a lack of standardization of activities and measurement errors. Artefactual readings can easily occur if patients are not properly instructed. Although editing procedures can eliminate outliers, it is often impossible to identify inaccurate readings included within the patient's trend. To optimize ambulatory blood pressure monitoring, health-care providers should be instructed adequately on how to perform this technique. Appropriate patient selection, a proper application of instrumentation and the checking of its performance, careful instructions to patients, the immediate evaluation of the patient's diary and 24 h tracing after completion of the recording should improve the results of ambulatory monitoring. CONCLUSIONS: A checklist of criteria that should be used for optimizing ambulatory monitoring in clinical practice should be proposed by the Consensus Conference on ambulatory blood pressure monitoring. To improve doctors' proficiency, strategies including educational protocols and training programmes should be implemented.     

Self monitoring versus ambulatory blood pressure monitoring]

Blood pressure is a variable parameter for which the isolated determination cannot be considered as a characteristic of the subject. Therefore, the clinical measurement of blood pressure constitutes the method of reference but presents limits and causes of errors which pose a problem for its validity in evaluating the average blood pressure level in certain patients. In order to overcome the limits of occasional measurement, different methods of blood pressure measurement have been proposed. Among these methods, self monitoring of blood pressure by the patient and 24 hour ambulatory blood pressure monitoring (ABPM) are the most used. Each of these methods presents advantages and disadvantages, indications and limits of use. The information obtained by each of them is of a different nature: these methods are not substitutes but are complementary. Self monitoring and ABPM seem to evaluate the pressure load better than clinical monitoring and are better correlated to the organic effects of hypertension and thus the cardiovascular morbidity and mortality, ABPM in particular. However, it remains to be clarified whether the use of these methods in the evaluation of cardiovascular risk and the therapeutic management of the hypertensive can improve the long term cardiovascular prognosis.     

Twenty-four-hour ambulatory blood pressure monitoring efficacy of perindopril/indapamide first-line combination in hypertensive patients: the REASON study

BACKGROUND: Circadian blood pressure (BP) measurements provide more information on hypertensive complications than office BP measurements. The purpose of this study was to analyze the efficacy of the first-line combination of perindopril 2 mg plus indapamide 0.625 mg versus atenolol 50 mg on BP parameters and variability over 24 h in patients with hypertension. METHODS: A double-blind, randomized, controlled, 12-month study comparing perindopril/indapamide and atenolol was performed in 201 patients (age 55.0 years) with uncomplicated sustained essential hypertension. Ambulatory BP measurements (ABPM) were done every 15 min over 24 h. RESULTS: After 1 year of treatment, the decrease in systolic BP was significantly greater for perindopril/indapamide than for atenolol during the entire 24-h period (-13.8 v -9.2 mm Hg), the daytime and the nighttime periods (P <.01). Diastolic blood pressure (DBP) variations were comparable for the two groups (-7.2 v -8.3 mm Hg, NS). Pulse pressure (PP) reduction was also significantly greater for perindopril/indapamide than for atenolol (for the whole 24 h, -6.6 v -0.9 mm Hg, P <.001). The through to peak (T/P) BP ratio and the smoothness index were comparable in the two groups for DBP. For systolic blood pressure (SBP), higher values of the T/P ratio (0.80 v 0.59) and the smoothness index (1.45 v 0.98; P <.02) were achieved for the perindopril/indapamide combination than for atenolol. CONCLUSIONS: The perindopril/indapamide first-line combination decreased SBP and PP more effectively than atenolol. Moreover, the BP control effect was smooth and consistent throughout the 24-h dosing interval and BP reduction variability was lower than the one induced by atenolol.     

The placebo effect in ambulatory blood pressure monitoring

The reduction of clinic blood pressure by placebo tablets in clinical trials of antihypertensive drugs is well established and health authorities require a placebo arm in these trials in order to know how much of the total reduction of blood pressure is attributable to the drug. Most authors now favor the hypothesis that, in contrast to clinic blood pressure measurements, ambulatory blood pressure monitoring (ABPM) is not subject to a placebo effect. Scientific evidence so far shows that ABPM recordings are affected by a negligible and clinically irrelevant placebo effect in short-term trials. Nevertheless, the results of the SYST-EUR study suggest that placebo treatment induces a reduction of blood pressure in old patients with isolated systolic hypertension even when blood pressure is measured by 24 h ABPM, and raise the question of whether a placebo arm is required in clinical trials when ABPM is used to measure changes in blood pressure. In this article, the evidence supporting and contradicting the hypothesis that placebo exerts an effect on ABPM and the possible explanations for the discrepancy are reviewed. My position is that clinical trials on antihypertensive drugs using ABPM should be designed with the same standards as those using clinic blood pressure measurements; that is, randomized, double-blind, placebo-controlled studies. This should be an absolute requirement in long-term trials. Short-term trials lasting no more than 12 weeks, particularly those focused on examining average changes in 24 h diastolic blood pressure, may be designed without a placebo arm.