Ambulatory Blood Pressure Monitoring: How Reproducible Is It?

We tested the reproducibility of ambulatory blood pressure monitoring (ABPM) by the use of agreement plots. Thirty-two normotensive volunteers underwent ABPM on four separate days (interval 28 days), on the same typical weekday. Sleeping time was restricted to the ABPM nighttime subperiod from 11:00 pm to 7:00 am. Twenty-four-hour average values—both systolic and diastolic—daytime average values, and nighttime average values, as well as standard deviation (SD) values, were analyzed for differences (analysis of variance). Adaptation occurred from the first to the fourth ABPM, ie, average 24 h, daytime, and nighttime values were lower (−1 to −3 mm Hg) during the fourth recording than the first (P < .05 to P < .01). The agreement analysis showed a surprisingly high agreement among the four data sets (ie, differences from ±2.54 to ±5.92 mm Hg; ±2 SD of the distribution). We concluded that reproducibility of ABPM seems excellent, but adaptation may occur, even in normotensive volunteers under research conditions. Caution must be paid before labeling a patient as hypertensive, because initial ABPM may yield higher values than later monitorings.     

Ambulatory Blood Pressure Monitoring Editing Criteria: Is Standardization Needed?

The effect of different editing methods on the reproducibility of ambulatory blood pressure and on its correlation with microalbuminuria was studied in a population of 584 stage I hypertensives participating in the Hypertension and Ambulatory Recording Venetia Study (HARVEST) Group. For systolic blood pressure (SBP), a modified version of the Casadei method showed the best reproducibility indices, followed by the original Casadei and the Kennedy methods. The Staessen, SpaceLabs, and A&D methods showed poorer indices, irrespective of whether calculations were made in recordings with more or less than 10% artifactual readings. For diastolic blood pressure (DBP), reproducibility indices did not substantially vary with the various editing procedures except for the Kennedy method, which showed a slightly better performance. Blood pressure variability (standard deviation) showed a better reproducibility with the original and modified versions of the Casadei and the Kennedy procedures than with the other methods, especially in the subjects with percentage of measurement errors greater than 10%. The correlation coefficients between 24-h SBP and albumin excretion rate ranged from 0.128 for the raw data to 0.154 for the data edited according to the Casadei procedures. For DBP, the correlation coefficients were similar except for DBP edited with the Kennedy method, which did not correlate with albumin excretion rate to a statistically significant level. These data suggest that, to make the results of different laboratories comparable, common ambulatory blood pressure editing criteria should be used. The modified version of the Casadei procedure, which is automatic and can be applied to recordings obtained from any device, should be regarded as the method of choice.     

Is It Possible to Shorten Ambulatory Blood Pressure Monitoring?

The aim of this investigation was to find a time segment in which average blood pressure (BP) has the best correlation with 24‐hour BP control. A total of 240 patients with full ambulatory BP monitoring (ABPM) were included; 120 had controlled BP (systolic BP [SBP] ≤135 mm Hg and diastolic BP [DBP] ≤85 mm Hg) and 120 had uncontrolled BP (SBP >135 mm Hg and/or DBP >85 mm Hg). Each ABPM was divided into 6‐ and 8‐hour segments. Evaluation for correlation between mean BP for each time segment and 24‐hour BP control was performed using receiver operating characteristic curve analysis and Youden''s index for threshold with the best sensitivity and specificity. The mean BP in the following segments showed the highest area under the curve (AUC) compared with average controlled 24‐hour BP: SBP 2 am to 8 am (AUC, 0.918; threshold value of 133.5 mm Hg, sensitivity−0.752 and specificity−0.904); SBP 2 pm to 10 pm (AUC, 0.911; threshold value of 138.5 mm Hg, sensitivity−0.803 and specificity−0.878); and SBP 6 am to 2 pm (AUC, 0.903; threshold value of 140.5 mm Hg, sensitivity−0.778 and specificity−0.888). The time segment 2 pm to 10 pm was shown to have good correlation with 24‐hour BP control (AUC >0.9; sensitivity and specificity >80%). This time segment might replace full ABPM as a screening measure for BP control or as abbreviated ABPM for patients with difficulty in performing full ABPM.

Blood pressure (BP) measured by ambulatory BP monitoring (ABPM) is more closely associated with target organ damage, and is considered the most accurate method to evaluate true BP.¹, ² In addition, ABPM is the only technique to evaluate nighttime BP and early morning surge.¹ Although ABPM is an important tool in evaluation and follow up of hypertensive patients, its use in clinical practice may be limited by availability, cost, and patient inconvenience. For accurate measurements, the patient is required to keep the cuff on the arm during the entire measurement period (usually 24 hours) as well as having to wear the monitor unit on the waist (by a belt or strap) during the day and keep it at the bedside at night.³ Because of these disadvantages, an easier and shorter method is required. Some studies compared various techniques for clinical BP measurements with full ABPM.³, ⁴ Ernst and colleagues⁵, ⁶ demonstrated the accuracy of a shortened ABPM session of 6 hours in classifying BP as controlled or uncontrolled. Due to the above difficulties in performing full ABPM and the current knowledge about optional shortened ABPM, we aimed to find a time segment during which average BP has the best correlation with 24‐hour BP control.     

Prognostic Importance of Ambulatory Blood Pressure Monitoring in Resistant Hypertension: Is It All that Matters?

Purpose of Review

This article reviews the current knowledge on the prognostic importance of ambulatory blood pressure (BP) monitoring parameters in patients with apparent treatment-resistant hypertension.

Recent Findings

Although mean 24-h ambulatory BPs have been consistently established as better cardiovascular risk predictors than clinic (office) BPs in several clinical settings, and ambulatory BP monitoring is generally indicated in patients with resistant hypertension; there were only five previous longitudinal prospective studies that specifically evaluated the prognostic importance of ambulatory BP monitoring parameters in resistant hypertensive patients. These studies are carefully reviewed here. In conjunction, they demonstrated that office BP levels have little, if any, prognostic value in resistant hypertensive patients. Otherwise, several ambulatory BP monitoring parameters are strong cardiovascular risk predictors, particularly nighttime sleep BPs and the non-dipping pattern. Most relevant, the ambulatory BP monitoring diagnosis of true resistant hypertension (i.e., patients with uncontrolled ambulatory BPs, either daytime or nighttime) doubled the risk of future occurrence of major cardiovascular events in contrast to patients with white-coat resistant hypertension (i.e., with controlled ambulatory BPs despite uncontrolled office BPs).

Summary

This review reinforces the pivotal role of serial ambulatory BP monitoring examinations in the clinical management of patients with resistant hypertension.

     

Masked Hypertension Assessed by Ambulatory Blood Pressure Versus Home Blood Pressure Monitoring: Is It the Same Phenomenon?

BACKGROUND: Masked hypertension is defined as normal clinic blood pressure (CBP) and elevated out-of-clinic blood pressure assessed using either self-monitoring of blood pressure (BP) by the patients at home (HBP) or ambulatory BP (ABP) monitoring. This study investigated the level of agreement between ABP and HBP in the diagnosis of masked hypertension. METHODS: Participants referred to an outpatient hypertension clinic had measurements of CBP (two visits), HBP (4 days), and ABP (24 h). The diagnosis of masked hypertension based on HBP (CBP <140/90 mm Hg and HBP > or =135/85) versus ABP (CBP <140/90 and awake ABP > or =135/85) was compared. RESULTS: A total of 438 subjects were included (mean age +/- SD, 51.5 +/- 11.6 years; 59% men and 41% women, 34% treated and 66% untreated). Similar proportions of subjects with masked hypertension were diagnosed by ABP (14.2%) and HBP (11.9%). In both treated and untreated subjects, the masked hypertension phenomenon was as common as the white coat phenomenon. Among 132 subjects with normal CBP, there was disagreement in the diagnosis of masked hypertension between the HBP and the ABP method in 23% of subjects for systolic and 30% for diastolic BP (kappa 0.56). When a 5-mm Hg gray zone for uncertain diagnosis was applied to the diagnostic threshold, the disagreement was reduced to 9% and 6% respectively. CONCLUSIONS: Similar proportions of subjects with masked hypertension are detected by ABP and HBP monitoring. Although disagreement in the diagnosis between the two methods is not uncommon, in the majority of these cases the deviation of the diagnostic BP above the threshold in not clinically important. Both ABP and HBP monitoring appear to be appropriate methods for the detection of masked hypertension.     

Chronotherapy of Hypertension with Angiotensin Receptor Blockers–A Meta-Analysis of Blood Pressure Measured by Ambulatory Blood Pressure Monitoring in Randomized Trials

BackgroundWe performed this meta-analysis evaluating the efficacy of chronotherapy of hypertension with angiotensin receptor blockers (ARBs).MethodsWe searched Pubmed, Web of Science, and Cochrane for all published randomized trials that compare antihypertensive effects of ARBs between bedtime dosing and awakening dosing. Blood pressure (BP) was measured by ambulatory BP monitoring in patients with mild or moderate essential hypertension.ResultsThe effects of ARBs on BP were assessed in 805 essential hypertensive patients included in 8 trials with a follow-up of 12 ± 3 weeks. The sleep-time systolic and diastolic BP (SBP, DBP) with bedtime dosing greatly decreased as compared with awakening dosing (weighted mean differences [WMD] for SBP WMD ?5.23 [95% confidence intervals (CI), ?7.27, ?3.20] mm Hg, p < 0.001; WMD for DBP ?2.94 [95% CI, ?4.52, ?1.36] mm Hg, p < 0.001). The reduction of daytime SBP (WMD 0.98 [95% CI, ?0.20, 2.17] mm Hg, p = 0.10), DBP (WMD 0.11 [95% CI, ?0.68, 0.89] mm Hg, p = 0.79), 24 hour SBP (WMD ?0.75 [95% CI, ?1.93, 0.42] mm Hg, p = 0.21) and DBP (WMD ?0. 77 [95% CI, ?1.55 0.01] mm Hg, p = 0.05) with bedtime dosing was similar with awakening dosing.ConclusionsBedtime dosing with ARBs is more effective in lowering sleep-time BP than awakening dosing in patients with essential hypertension, suggesting a utilization of chronotherapy of hypertension with ARBs to reduce sleep-time high BP. Larger multi-ethnic studies are needed to investigate the efficacy of chronotherapy of hypertension.     

Is It Possible to Manage Hypertension and Evaluate Therapy Without Ambulatory Blood Pressure Monitoring?

In the management of patients with hypertension, blood pressure (BP) has been traditionally measured in the physician's office. The contribution of ambulatory BP monitoring (ABPM) to the management of hypertensive patients has been increasingly recognized through clinical and epidemiological research. Ambulatory BP monitoring can enhance the ability to detect white-coat or masked hypertension, determine the absence of nocturnal dipping status, and evaluate BP control in patients on antihypertensive therapy. Recently, the United Kingdom National Clinical Guideline Centre published guidelines for the clinical management of primary hypertension in adults, recommending the routine use of ABPM to make the initial diagnosis of hypertension. While the advantages of ABPM are apparent from a clinical perspective, its use should be considered in relation to the cost of the equipment, data evaluation, and staff training as well as the possible inconvenience to the patient. In this review, we summarize the clinical importance of ABPM and discuss the current guidelines for establishing the diagnosis of hypertension.     

How Well Does a Shortened Time Interval Characterize Results of a Full Ambulatory Blood Pressure Monitoring Session?

Ambulatory blood pressure monitoring (ABPM) is useful in evaluating cardiovascular risk but requires significant time. The authors examined how closely shortened time intervals correlate with the systolic blood pressure (BP) determined from a full 24-hour ABPM session in 1004 ABPM recordings. After excluding the first hour, Pearson correlations performed for the mean systolic BP of the subsequent 3-, 5-, and 7-hour periods (4, 6, and 8 hours total) with the entire, and remainder of the session, demonstrated greatest improvement in correlation when the session is increased from 4 to 6 hours. Bland-Altman analysis of the 6-hour time period revealed a mean difference of 5.41 mm Hg compared with the full session mean. The authors conclude that 6-hour ABPM can approximate the overall mean BP obtained from full 24-hour ABPM. However, shortened sessions do not characterize the influence of circadian variation on the 24-hour mean BP and may overestimate the 24-hour BP levels.     

Home Blood Pressure Monitoring: How Good a Predictor of Long-Term Risk?

Most management decisions for the diagnosis and treatment of hypertension are made using blood pressure (BP) measurements made in the clinic. However, home BP recordings may be of superior prognostic value. In this review, we show that home BP recordings are generally superior to clinic BP measurements in predicting long-term prognosis. Home BP has been shown to significantly predict important end points including all-cause mortality, progression of chronic kidney disease, and functional decline in the elderly. In addition, home BP recordings significantly and strongly predict cardiovascular events. These findings are robust, as they concur despite having been studied in disparate populations, using heterogeneous methods of clinic and home BP measurement, and with varied methods of statistical analysis. The advantages of home BP recordings are not due solely to a larger number of measurements, and they extend to the elderly, patients with chronic kidney disease, and those on hemodialysis. Because home BP recordings combine improved accuracy with the advantages of low cost and easy implementation, most patients with known or suspected hypertension should have their BP assessed and managed by means of home BP recordings.     

Blood Pressure Measurement: Sitting and Standing?

Prior to discussing some thoughts about positional changes in blood pressure, I'd like to comment on the me- asurement of blood pressure.It is rare for a medical student, a resident-in-training, a cardiovascular fellow-in-training, or even a practicing or academic cardiologist to take the patient's blood pressure. I would even go so far as to say that it is uncommon for a registered nurse to measure blood pressure. Copyright (c) 2008 Wiley Periodicals, Inc.     

Hypertension Prevalence,Awareness, Treatment,and Control: Should 24‐Hour Ambulatory Blood Pressure Monitoring be the Tool of Choice?

We aimed to examine hypertension prevalence, awareness, treatment and control in a community sample and investigate the impact of using 24 hour ABPM. Office blood pressure (BP) was taken from the electronic health record. Study BP was measured by standardised methods. Participants were invited to undergo ABPM. Hypertension was defined by accepted thresholds or anti‐hypertensive use. Standardised questions assessed awareness and treatment. Control was defined as anti‐hypertensive use with BP below normal threshold. There were 931 (45%) participants with office BP, study BP and ABPM. By study BP, hypertension prevalence was 60%, awareness 59%, 60% were treated and 46% controlled. By daytime ABPM threshold, prevalence was 61%, awareness 59%, 59% were treated and 54% controlled. ABPM reclassified 13.5% from normotensive to hypertensive and 14.5% from hypertensive to normotensive. ABPM may not hugely impact population hypertension prevalence but at an individual level it reduces misclassification and facilitates more appropriate management.