24-hour Ambulatory Blood Pressure Recordings Research Articles

Nocturnal blood pressure dipping and left ventricular hypertrophy among hypertensive outpatients in a Ghanaian hospital

Objectives: To investigate the association between the extent of nocturnal systolic blood pressure decline and left ventricular hypertrophy in patients with primary hypertension who were receiving antihypertensive drug therapy.Design: This was a cross-sectional hospital-based study from November 2020 to March 2021.Setting: The study was conducted at the Polyclinic of Korle Bu Teaching Hospital, Ghana.Participants: Outpatients ≥18 years old with primary hypertension who were receiving antihypertensive drug therapy.Interventions: Each participant underwent a 24-hour ambulatory blood pressure monitoring and a transthoracic echocardiogram.Main outcome measures: Left ventricular hypertrophy and the extent of mean systolic blood pressure decline during sleep.Results: 180 participants were recruited, comprising 110 (61.1%) females. The participants’ mean (±SD) age was 57.6 ± 11.0 years. 80% had a non-dipping blood pressure pattern, and 43.9% had left ventricular hypertrophy. Uncontrolled office blood pressure was an independent predictor of left ventricular hypertrophy in these patients (AOR 2.010, 95% CI 1.048-3.855, p=0.036); however, a non-dipping nocturnal systolic blood pressure status was not (AOR 1.849, 95% CI 0.850-4.022, p=0.121). 61.1% had abnormal left ventricular geometry, with concentric hypertrophy being the predominant geometric pattern.Conclusion: Left ventricular hypertrophy and non-dipping nocturnal blood pressure were common in these hypertensive Ghanaian patients on antihypertensive therapy. Left ventricular hypertrophy was associated with uncontrolled office blood pressure but not the extent of nocturnal systolic blood pressure declines during a single 24-hour ambulatory blood pressure recording.

Study protocol for the Heads-Up trial: a phase II randomized controlled trial investigating head-up tilt sleeping to alleviate orthostatic intolerance in Parkinson’s Disease and parkinsonism

BackgroundIn persons with Parkinson’s Disease (PD) or certain forms of atypical parkinsonism, orthostatic hypotension is common and disabling, yet often underrecognized and undertreated. About half of affected individuals also exhibit supine hypertension. This common co-occurrence of both orthostatic hypotension and supine hypertension complicates pharmacological treatments as the treatment of the one can aggravate the other. Whole-body head-up tilt sleeping (HUTS) is the only known intervention that may improve both. Evidence on its effectiveness and tolerability is, however, lacking, and little is known about the implementability.MethodsIn this double-blind multicenter randomized controlled trial (phase II) we will test the efficacy and tolerability of HUTS at different angles in 50 people with PD or parkinsonism who have both symptomatic orthostatic hypotension and supine hypertension. All participants start with one week of horizontal sleeping and subsequently sleep at three different angles, each maintained for two weeks. The exact intervention will vary between the randomly allocated groups. Specifically, the intervention group will consecutively sleep at 6°, 12° and 18°, while the delayed treatment group starts with a placebo angle (1°), followed by 6° and 12°. We will evaluate tolerability using questionnaires and compliance to the study protocol. The primary endpoint is the change in average overnight blood pressure measured by a 24-hour ambulatory blood pressure recording. Secondary outcomes include orthostatic blood pressure, orthostatic tolerance, supine blood pressure, nocturia and various other motor and non-motor tests and questionnaires.DiscussionWe hypothesize that HUTS can simultaneously alleviate orthostatic hypotension and supine hypertension, and that higher angles of HUTS are more effective but less tolerable. The Heads-Up trial will help to clarify the effectiveness, tolerability, and feasibility of this intervention at home and can guide at-home implementation.Trial registrationClinicalTrials.gov NCT05551377; Date of registration: September 22, 2022.

Blood Pressure Variability: Mechanisms, Measurement, Subtypes, and Clinical Implications

The complex topic of short- and long-term blood pressure (BP) variability confounds the diagnosis, classification, and management of hypertension. True pathophysiologic BP variation (systematic and non-systematic deviations between- and within-individuals) is related to heart rate, respiration, complex responses of the sympathetic nervous system, vascular reactivity, and arterial stiffness. Measurement errors (systematic biases and random error) further compound the analysis. Most studies use serial clinic BP values, 24-hour ambulatory BP recordings, or home BP values with standard statistical indicators (standard deviation, variance, or coefficient of variation) or absolute real variability (mean difference of successive values). Clinical impact in retrospective secondary analyses includes a modest increase in cardiovascular disease (CVD) risk (equivalent to a few mmHg in mean systolic BP) yet questions remain whether adjustment for mean BP is needed. BP variability is reduced to a small degree by calcium antagonists and increased by ACE inhibitors, beta-blockers, and alpha-blockers but no interventional trial has addressed the question of whether reducing BP variability confers CVD risk protection. BP variability is not specifically discussed in practice guidelines but it is tacitly acknowledged by recommendations to repeat BP measurements, standardize technique, and confirm the hypertension diagnosis by home or ambulatory BP measurements to account for the “white coat effect.” There is no formal consensus on how to quantitate or manage BP variability despite a real-world need for better diagnostic and therapeutic guidance. Practitioners should thus focus on control of (mean) BP using combinations of agents that improve CVD outcomes. Future consensus guidance should directly address BP variability and should include educational materials for physicians, patient-contact staff, and patients.

Ambulatory Blood Pressure Monitoring to Diagnose and Manage Hypertension.

This review portrays how ambulatory blood pressure (BP) monitoring was established and recommended as the method of choice for the assessment of BP and for the rational use of antihypertensive drugs. To establish much-needed diagnostic ambulatory BP thresholds, initial statistical approaches evolved into longitudinal studies of patients and populations, which demonstrated that cardiovascular complications are more closely associated with 24-hour and nighttime BP than with office BP. Studies cross-classifying individuals based on ambulatory and office BP thresholds identified white-coat hypertension, an elevated office BP in the presence of ambulatory normotension as a low-risk condition, whereas its counterpart, masked hypertension, carries a hazard almost as high as ambulatory combined with office hypertension. What clinically matters most is the level of the 24-hour and the nighttime BP, while other BP indexes derived from 24-hour ambulatory BP recordings, on top of the 24-hour and nighttime BP level, add little to risk stratification or hypertension management. Ambulatory BP monitoring is cost-effective. Ambulatory and home BP monitoring are complimentary approaches. Their interchangeability provides great versatility in the clinical implementation of out-of-office BP measurement. We are still waiting for evidence from randomized clinical trials to prove that out-of-office BP monitoring is superior to office BP in adjusting antihypertensive drug treatment and in the prevention of cardiovascular complications. A starting research line, the development of a standardized validation protocol for wearable BP monitoring devices, might facilitate the clinical applicability of ambulatory BP monitoring.

Covariables of Myocardial Function in Women and Men with Increased Body Mass Index.

IntroductionSex-difference in types of cardiac organ damage has been reported in subjects with increased body mass index (BMI). However less is known about sex-differences in left ventricular (LV) myocardial function assessed by global longitudinal strain (GLS) in these subjects.Methods493 subjects (mean age 47 ± 9 years, 61% women) with BMI > 27.0 kg/m2 and without known cardiac disease underwent 24-hour (24h) ambulatory blood pressure (BP) recording, body composition analysis, carotid-femoral pulse wave velocity (PWV) measurement and echocardiography. LV peak systolic GLS was measured by two-dimensional speckle tracking echocardiography and LV ejection fraction (EF) by biplane Simpson’s method. Insulin sensitivity was assessed by homeostatic model of insulin resistance (HOMA-IR).ResultsWomen had higher prevalence of increased waist circumference (99% vs. 82%), lower prevalence of hypertension (59 vs. 74%), and lower serum triglycerides (1.3 ± 0.7 vs. 1.7 ± 0.9 mmol/L) and carotid-femoral PWV (7.3 ± 1.6 vs. 7.7 ± 1.6 m/s) compared to men (all p < 0.05). Women also had higher (more negative) GLS compared to men (− 19.9 ± 3.0 vs. − 18.6 ± 3.0%, p < 0.001), while EF did not differ between sexes. In multivariable linear regression analyses, lower GLS in women was associated with higher waist circumference and PWV and with lower EF (all p < 0.05). In men, lower GLS was associated with higher waist circumference and HOMA-IR, and with lower EF (all p < 0.05).ConclusionsAmong subjects with increased BMI, GLS was higher in women than men. Lower GLS was associated with abdominal obesity in both sexes, and with impaired glucose metabolism in men, and with higher arterial stiffness in women.Trial registrationhttps://www.clinicaltrials.gov NCT02805478, first registered 20.06.16.

Effects on 24-hour blood pressure variability of ace-inhibition and calcium channel blockade as monotherapy or in combination

Cardiovascular events in hypertensives are associated with elevated average blood pressure (BP) and higher short-term BP variability (V), but little is known on treatment effects on BPV and on how to assess changes in short-term BPV. Aim of our study was to address the methodology of short-term BPV assessment and its reduction by Lercanidipine (L) or Enalapril (E) and their combination, through analysis of 24-hour ambulatory BP recordings from two studies including subjects of different age. Study-1: 64 middle-age hypertensives (52.9 ± 9.5 yrs) received L and E s.i.d. at 10 mg (L10, E10) or 20 mg doses (L20, E20) for 8 weeks. Study-2: 66 elderly hypertensives (65.5 ± 4.7 yrs) received placebo, L10, E20 and L10 + E20 s.i.d. for 4 weeks. In middle-age subjects, both L and E decreased mean BP and, at the highest dose, also short-term BPV. In elderly subjects, L10 alone or in combination with E20 reduced BPV. Treatment-induced reductions in BP levels and BPV were uncorrelated. Different methods for short-term BPV assessment did not always provide superimposable results in the elderly. Our study supports a better reduction of BPV by L in the elderly and by E + L combination at any age, suggesting BPV reduction to be independent from reduction in average BP.

Obese Hypertensive Men Have Lower Circulating Proatrial Natriuretic Peptide Concentrations Despite Greater Left Atrial Size.

Obese persons have lower circulating natriuretic peptide (NP) concentrations. It has been proposed that this natriuretic handicap plays a role in obesity-related hypertension. In contrast, hypertensive patients with left atrial enlargement have higher circulating NP concentrations. On this background, we investigated whether obese hypertensive men could have lower circulating NP concentrations despite evidence of pressure-induced greater left atrial size. We examined 98 obese men (body mass index [BMI] ≥ 30.0 kg/m2) and 27 lean normotensive men (BMI 20.0-24.9 kg/m2). All men were healthy, medication free, with normal left ventricular ejection fraction. We measured blood pressure using 24-hour ambulatory blood pressure (ABP) recordings. Hypertension was defined as 24-hour ABP ≥ 130/80 mm Hg, and normotension was defined as 24-hour ABP < 130/80 mm Hg. We determined left atrial size using echocardiography, and we measured fasting serum concentrations of midregional proatrial NP (MR-proANP). Of the 98 obese men, 62 had hypertension and 36 were normotensive. The obese hypertensive men had greater left atrial size (mean ± SD: 28.7 ± 6.0 ml/m2) compared with the lean normotensive men (23.5 ± 4.5 ml/m2) and the obese normotensive men (22.7 ± 5.1 ml/m2), P < 0.01. Nevertheless, despite evidence of pressure-induced greater left atrial size, the obese hypertensive men had lower serum MR-proANP concentrations (median [interquartile range]: 48.5 [37.0-64.7] pmol/l) compared with the lean normotensive men (69.3 [54.3-82.9] pmol/l), P < 0.01, whereas the obese normotensive men had serum MR-proANP concentrations in between the 2 other groups (54.1 [43.6-62.9] pmol/l). Despite greater left atrial size, obese hypertensive men have lower circulating MR-proANP concentrations compared with lean normotensive men.

Cardiovascular Risk Associated With White-Coat Hypertension: Con Side of the Argument.

Cardiovascular Risk Associated With White-Coat Hypertension: Con Side of the Argument.

PP.15.06] BLOOD PRESSURE VARIABILITY IN HYPERTENSIVE PATIENTS AND DIASTOLIC/ SYSTOLIC FUNCTION OF THE LEFT VENTRICLE

Objective: Our aim was to study any possible correlation between indices of diastolic/ systolic function of the left ventricle to the 24-hour blood pressure (BP) variability among hypertensive patients. Design and method: 845 hypertensive patients (438 males), treated (N = 222) or newly diagnosed untreated (N = 623), mean age of 52 years, body mass index: 27 kg/m2, mean systolicBP/ diastolicBP: 143/91 mmHg and mean heart rate of 76 beats per minute, underwent 24-hour ambulatory BP recording and transthoracic echocardiographic/Doppler exam. The early-diastolic and end-diastolic velocities of the transmitral valve flow were recorded. In a subgroup of 105 patients, indices of diastolic and systolic function of the left ventricle were measured using Tissue Doppler Imaging (TDI). The aforementioned parameters were correlated on the 24-hour BP variability and possible correlations between them was examined for values of 24-hour SBP variability >15 mmHg or <15 mmHg.Conclusions: In hypertensive patients, treated or newly diagnosed untreated, the 24-hour variability of the SBP significantly correlates principally with indices of left ventricle's diastolic function and its filling pressures, as well as with indices of its systolic function.

Prognosis in Relation to Blood Pressure Variability

Prognosis in Relation to Blood Pressure Variability

Decreased orthostatic adrenergic reactivity in non-dipping postural tachycardia syndrome.

Whether non-dipping - the loss of the physiologic nocturnal drop in blood pressure - among patients with postural tachycardia syndrome (POTS) is secondary to autonomic neuropathy, a hyperadrenergic state, or other factors remains to be determined. In 51 patients with POTS (44 females), we retrospectively analyzed 24-hour ambulatory blood pressure recordings, laboratory indices of autonomic function, orthostatic norepinephrine response, 24-hour natriuresis and peak exercise oxygen consumption. Non-dipping (<10% day-night drop in systolic blood pressure) was found in 55% (n=28). Dippers and non-dippers did not differ in: 1) baseline characteristics including demographic and clinical profile, sleep duration, daytime blood pressure, 24-hour natriuresis, and peak exercise oxygen consumption; 2) severity of laboratory autonomic deficits (sudomotor, cardiovagal and adrenergic); 3) frequency of autonomic neuropathy (7/23 vs. 8/28, P=0.885); 4) supine resting heart rate (75.3±14.0bpm vs. 74.0±13.8bpm, P=0.532); or 5) supine plasma norepinephrine level (250.0±94.9pg/ml vs. 207.0±86.8pg/ml, P=0.08). However, dippers differed significantly from non-dippers in that they had significantly greater orthostatic heart rate increment (43±16bpm vs. 35±10bpm, P=0.007) and significantly greater orthostatic plasma norepinephrine increase (293±136.6pg/ml vs. 209±91.1pg/ml, P=0.028). Our data indicate that in patients with POTS, a non-dipping blood pressure profile is associated with a reduced orthostatic sympathetic reactivity not accounted for by autonomic neuropathy.

Blood Pressure Load Does Not Add to Ambulatory Blood Pressure Level for Cardiovascular Risk Stratification

Experts proposed blood pressure (BP) load derived from 24-hour ambulatory BP recordings as a more accurate predictor of outcome than level, in particular in normotensive people. We analyzed 8711 subjects (mean age, 54.8 years; 47.0% women) randomly recruited from 10 populations. We expressed BP load as percentage (%) of systolic/diastolic readings ≥135/≥85 mm Hg and ≥120/≥70 mm Hg during day and night, respectively, or as the area under the BP curve (mm Hg×h) using the same ceiling values. During a period of 10.7 years (median), 1284 participants died and 1109 experienced a fatal or nonfatal cardiovascular end point. In multivariable-adjusted models, the risk of cardiovascular complications gradually increased across deciles of BP level and load (P<0.001), but BP load did not substantially refine risk prediction based on 24-hour systolic or diastolic BP level (generalized R(2) statistic ≤0.294%; net reclassification improvement ≤0.28%; integrated discrimination improvement ≤0.001%). Systolic/diastolic BP load of 40.0/42.3% or 91.8/73.6 mm Hg×h conferred a 10-year risk of a composite cardiovascular end point similar to a 24-hour systolic/diastolic BP of 130/80 mm Hg. In analyses dichotomized according to these thresholds, increased BP load did not refine risk prediction in the whole study population (R(2)≤0.051) or in untreated participants with 24-hour ambulatory normotension (R(2)≤0.034). In conclusion, BP load does not improve risk stratification based on 24-hour BP level. This also applies to subjects with normal 24-hour BP for whom BP load was proposed to be particularly useful in risk stratification.

How Many Measurements Are Needed to Estimate Blood Pressure Variability Without Loss of Prognostic Information?

Average real variability (ARV) is a recently proposed index for short-term blood pressure (BP) variability. We aimed to determine the minimum number of BP readings required to compute ARV without loss of prognostic information. ARV was calculated from a discovery dataset that included 24-hour ambulatory BP measurements for 1,254 residents (mean age = 56.6 years; 43.5% women) of Copenhagen, Denmark. Concordance between ARV from full (≥80 BP readings) and randomly reduced 24-hour BP recordings was examined, as was prognostic accuracy. A test dataset that included 5,353 subjects (mean age = 54.0 years; 45.6% women) with at least 48 BP measurements from 11 randomly recruited population cohorts was used to validate the results. In the discovery dataset, a minimum of 48 BP readings allowed an accurate assessment of the association between cardiovascular risk and ARV. In the test dataset, over 10.2 years (median), 806 participants died (335 cardiovascular deaths, 206 cardiac deaths) and 696 experienced a major fatal or nonfatal cardiovascular event. Standardized multivariable-adjusted hazard ratios (HRs) were computed for associations between outcome and BP variability. Higher diastolic ARV in 24-hour ambulatory BP recordings predicted (P < 0.01) total (HR = 1.12), cardiovascular (HR = 1.19), and cardiac (HR = 1.19) mortality and fatal combined with nonfatal cerebrovascular events (HR = 1.16). Higher systolic ARV in 24-hour ambulatory BP recordings predicted (P < 0.01) total (HR = 1.12), cardiovascular (HR = 1.17), and cardiac (HR = 1.24) mortality. Forty-eight BP readings over 24 hours were observed to be adequate to compute ARV without meaningful loss of prognostic information.

Peripheral Augmentation Index is Associated With the Ambulatory Arterial Stiffness Index in Patients With Hypertension

Background: Vascular dysfunction is highly prevalent if not ubiquitous in patients with hypertension. We compared two different measures of vascular function obtained from digital volume waveforms with measures of ventricular-vascular load derived from 24-hour blood pressure (BP) recordings in patients with hypertension. Methods: Digital pulsatile volume waveforms were captured via plethysmography (peripheral arterial tone, PAT) and used to derive augmentation index (a measure of ventricular-vascular coupling) and the pulse wave amplitude-reactive hyperemia index (a measure of microvascular reactivity). Ambulatory arterial stiffness index (AASI) and the BP variability ratio (BPVR) were derived from 24-hour ambulatory BP recordings. Results: There was a positive association between PAT-AIx and AASI (r = 0.52, P 0.05). PWA-RHI was not associated with AASI or BPVR (P > 0.05). Conclusions: PAT-AIx is associated with ambulatory measures of vascular function and may offer clinical insight into vascular burden and cardiovascular disease risk in patients with hypertension independent of information obtained from PWA-RHI. Cardiol Res. 2011;2(5):218-223 doi: https://doi.org/10.4021/cr92w

Peripheral Augmentation Index is Associated With the Ambulatory Arterial Stiffness Index in Patients With Hypertension.

BackgroundVascular dysfunction is highly prevalent if not ubiquitous in patients with hypertension. We compared two different measures of vascular function obtained from digital volume waveforms with measures of ventricular-vascular load derived from 24-hour blood pressure (BP) recordings in patients with hypertension.MethodsDigital pulsatile volume waveforms were captured via plethysmography (peripheral arterial tone, PAT) and used to derive augmentation index (a measure of ventricular-vascular coupling) and the pulse wave amplitude-reactive hyperemia index (a measure of microvascular reactivity). Ambulatory arterial stiffness index (AASI) and the BP variability ratio (BPVR) were derived from 24-hour ambulatory BP recordings.ResultsThere was a positive association between PAT-AIx and AASI (r = 0.52, P < 0.05). There was also a positive association between PAT-AIx and BPVR (r = 0.37, P < 0.05). PAT-AIx was not associated with PWA-RHI (r = -0.14, P > 0.05). PWA-RHI was not associated with AASI or BPVR (P > 0.05).ConclusionsPAT-AIx is associated with ambulatory measures of vascular function and may offer clinical insight into vascular burden and cardiovascular disease risk in patients with hypertension independent of information obtained from PWA-RHI.

Prognostic Value of Reading-to-Reading Blood Pressure Variability Over 24 Hours in 8938 Subjects From 11 Populations

In previous studies, of which several were underpowered, the relation between cardiovascular outcome and blood pressure (BP) variability was inconsistent. We followed health outcomes in 8938 subjects (mean age: 53.0 years; 46.8% women) randomly recruited from 11 populations. At baseline, we assessed BP variability from the SD and average real variability in 24-hour ambulatory BP recordings. We computed standardized hazard ratios (HRs) while stratifying by cohort and adjusting for 24-hour BP and other risk factors. Over 11.3 years (median), 1242 deaths (487 cardiovascular) occurred, and 1049, 577, 421, and 457 participants experienced a fatal or nonfatal cardiovascular, cardiac, or coronary event or a stroke. Higher diastolic average real variability in 24-hour ambulatory BP recordings predicted (P<or=0.03) total (HR: 1.14) and cardiovascular (HR: 1.21) mortality and all types of fatal combined with nonfatal end points (HR: >or=1.07) with the exception of cardiac and coronary events (HR: <or=1.02; P>or=0.58). Higher systolic average real variability in 24-hour ambulatory BP recordings predicted (P<0.05) total (HR: 1.11) and cardiovascular (HR: 1.16) mortality and all fatal combined with nonfatal end points (HR: >or=1.07), with the exception of cardiac and coronary events (HR: <or=1.03; P>or=0.54). SD predicted only total and cardiovascular mortality. While accounting for the 24-hour BP level, average real variability in 24-hour ambulatory BP recordings added <1% to the prediction of a cardiovascular event. Sensitivity analyses considering ethnicity, sex, age, previous cardiovascular disease, antihypertensive treatment, number of BP readings per recording, or the night:day BP ratio were confirmatory. In conclusion, in a large population cohort, which provided sufficient statistical power, BP variability assessed from 24-hour ambulatory recordings did not contribute much to risk stratification over and beyond 24-hour BP.

Dizzy Spells Complicating Hypertension Management

Dizzy Spells Complicating Hypertension Management

Introduction to the Seventh International Workshop on Structure and Function of the Vascular System

The Seventh International Workshop on Structure and Function of the Vascular System was held in Paris from March 12 through March 14, 2009. As with the preceding workshop (2007) the focus of the meeting shifted from large arteries toward a more integrative view on the structure and function of the vascular system, including the microcirculation. Recent insights have underlined the two-way traffic between the macro- and the microcirculation. On the one hand, pulse pressure generated in the macrocirculation penetrates deeper into the microcirculation than was previously believed. Increased pulse pressure at the level of the microcirculation causes functional and structural changes in the small vessels that contribute importantly to target organ damage. This is particularly the case in the renal pre- and postglomerular arterioles. On the other hand, the microcirculation is an important site of wave reflections in the arterial tree. Thereby, abnormalities in the microcirculation influence the contour of the pressure wave and the height of pulse pressure in the macrocirculation. A third potential interaction between the macro- and the microcirculation is the vaso-vasorum. Small arterioles have been found in the walls of larger arteries and may play a role in the structure and function of these arteries. Hypertensive disease is characterized by a “bad loop” between the macro- and microcirculation that maintains elevated blood pressure and causes target organ damage. During the three-day symposium nine sessions were held. The first dealt with arterial stiffness and was opened with a lecture by Gary Mitchell. He reviewed how excessive pressure pulsatility leads to target organ damage on a microvascular level. Ian Wilkinson subsequently proposed that changes in endothelial nitric oxide production resulting from stiffness-induced alterations in local shear stress may underlie damage of the microcirculation.1 Patrick Lacolley focused on the role of integrins as mediators of stiffness-induced decrease of …

Determinants of the Ambulatory Arterial Stiffness Index in 7604 Subjects From 6 Populations

The ambulatory arterial stiffness index (AASI) is derived from 24-hour ambulatory blood pressure recordings. We investigated whether the goodness-of-fit of the AASI regression line in individual subjects (r(2)) impacts on the association of AASI with established determinants of the relation between diastolic and systolic blood pressures. We constructed the International Database on the Ambulatory Blood Pressure in Relation to Cardiovascular Outcomes (7604 participants from 6 countries). AASI was unity minus the regression slope of diastolic on systolic blood pressure in individual 24-hour ambulatory recordings. AASI correlated positively with age and 24-hour mean arterial pressure and negatively with body height and 24-hour heart rate. The single correlation coefficients and the mutually adjusted partial regression coefficients of AASI with age, height, 24-hour mean pressure, and 24-hour heart rate increased from the lowest to the highest quartile of r(2). These findings were consistent in dippers and nondippers (night:day ratio of systolic pressure >or=0.90), women and men, and in Europeans, Asians, and South Americans. The cumulative z score for the association of AASI with these determinants of the relation between diastolic and systolic blood pressures increased curvilinearly with r(2), with most of the improvement in the association occurring above the 20th percentile of r(2) (0.36). In conclusion, a better fit of the AASI regression line enhances the statistical power of analyses involving AASI as marker of arterial stiffness. An r(2) value of 0.36 might be a threshold in sensitivity analyses to improve the stratification of cardiovascular risk.

Recent advances in automated blood pressure measurement

During the past 15 years, clinical outcome studies have consistently reported that home and 24-hour ambulatory blood pressure recordings provide a significantly better measure of cardiovascular risk than do manual blood pressure readings taken in the office or clinic. The advent of automated sphygmomanometers that record blood pressure with the patient alone in the examining room will be the next major change in our approach to recording blood pressure. These automated devices virtually eliminate the white coat response and their readings correlate significantly better with the ambulatory blood pressure compared with manual office blood pressure readings. The principal finding from recent research into automated blood pressure measurement is that the presence of an observer during the actual reading in itself provokes the white coat response.