White-coat hypertension: a selection bias? Harvest Study Investigators. Hypertension and Ambulatory Recording Venetia Study

Reproducibility of masked hypertension and office-based hypertension: a systematic review and meta-analysis

Blood pressure (BP) phenotypes have a prognostic significance for target organ damage in long-term studies. However, it remains uncertain whether a single baseline phenotype classification is reproducible over time and represents accurately the patients' BP status. The aim of this study was to systematically investigate the reproducibility of masked hypertension and office-based hypertension either with ambulatory BP monitoring (ABPM) or home BP monitoring (HBPM). PubMed, Cochrane Library and Web of Science were searched to identify studies with paired baseline office BP and ABPM or HBPM measurements at two timepoints. The outcome of the analysis was the individual phenotype reproducibility between the baseline and follow-up timepoints. The used effect measure was Cohen's kappa coefficient. We found 15 studies eligible for the meta-analysis enrolling a total of 5729 patients. The reproducibility of masked hypertension was better with ABPM, kappa reliability test: 0.41 [95% confidence interval (CI): 0.32-0.49], than with HBPM, kappa reliability test: 0.26 (95% CI: 0.10-0.40). The reproducibility of office-based hypertension with both methods was low, indicating slight agreement. Kappa reliability test was slightly better with ABPM (κ: 0.27, 95% CI: 0.12-0.41) than with HBPM (κ: 0.18, 95% CI: 0.08-0.27). This systematic review and meta-analysis show a slight to fair reproducibility of masked hypertension and office-based hypertension assessed through ABPM and HBPM. Considering that poor reproducibility may be a result of office BP measurements, an ABPM/HBPM-based strategy should be established for the evaluation and treatment of patients with masked hypertension or office-based hypertension.

The HARVEST. Looking for optimal management of young people with stage 1 hypertension

In the last few decades there has been much debate about the management of low-risk stage 1 hypertension in youth. In this article, we review the main findings of the HARVEST cohort accrued over 30 years, highlighting the contribution of this study to the existing literature. Tachycardia and sympathetic overdrive were closely intertwined in our HARVEST participants, promoting the development of sustained hypertension, metabolic abnormalities, and increased susceptibility to vascular complications. Short-term blood pressure variability in this age group had a prognostic power even greater than that of average 24h blood pressure. In the HARVEST participants, changes in left ventricular anatomy and contractility were the earliest signs of hypertensive cardiac involvement, whereas left ventricular filling was only marginally affected. Our results highlighted the role of glomerular hyperfiltration in determining microalbuminuria and renal damage in the early stage of hypertension. The genetic approach provided an important contribution to risk stratification and patient management. The HARVEST confirmed the importance of maintaining a good lifestyle for preventing the onset of hypertension, diabetes and cardiovascular events. Isolated systolic hypertension in the first decades of life appeared as a heterogeneous condition. To establish whether antihypertensive drug treatment should be started in this condition the clinician should consider the individual cardiovascular risk profile, the level of office mean BP and central BP. Despite recent progress in our knowledge, systolic hypertension still represents a challenging issue for the clinician. Hopefully, the HARVEST will continue to contribute data that help to fill the present gaps in evidence.

White Coat Hypertension: to Treat or Not to Treat?

Definition of white coat hypertension (WCH) traditionally relies on elevated office blood pressure (BP) during repeated visits concomitant with normal out-of-office BP values, as assessed by home and/or 24-h ambulatory BP monitoring measurements. Accumulating evidence focusing on the association of WCH with target organ damage and, more importantly, with cardiovascular events indicates that the risk conveyed by this condition is intermediate between normotension and sustained hypertension. This article will review a number of issues concerning WCH with particular emphasis on the following: (1) prevalence and clinical correlates, (2) association with target organ damage and cardiovascular events, (3) therapeutic interventions. Data will refer to the original WCH definition, based on out-of-office BP determined by 24-h ambulatory BP monitoring; at variance from home BP measurement, this approach rules out the potentially confounding effect of a clinically relevant abnormal BP phenotype such as isolated nocturnal hypertension.

White-Coat Hypertension: the Neglected Subgroup in Hypertension

The clinical prognostic importance of white coat hypertension (WCH), that is, the clinical condition characterized by an increase of office but a normal ambulatory or home blood pressure (BP) is since a long time matter of considerable debate. WCH accounts for a consistent portion of hypertensive patients (up to 30–40%), particularly when hypertension is mild or age is more advanced. Although scanty and inconsistent information is available on the response of office and out-office BP to antihypertensive treatment and the cardiovascular (CV) protection provided by treatment, an increasing body of evidence focusing on the association of WCH with CV risk factors, subclinical cardiac and extra-cardiac organ damage and, more importantly, with CV events indicates that the risk entailed by this condition is intermediate between true normotension and sustained hypertension. This review will address a number of issues concerning WCH with particular attention to prevalence and clinical correlates, relation with subclinical target organ damage and CV morbidity/mortality, therapeutic perspectives. Several topics covered in this review are based on data acquired over the past 20 years by the Pressioni Arteriose Monitorate E Loro Associazioni (PAMELA) study, a longitudinal survey performed by our group on the general population living in the surroundings of Milan area in the north part of Italy.

Clinical significance of home blood pressure measurements for the prevention and management of high blood pressure

1. Ambulatory blood pressure (ABP) monitoring (M) provides BP information at many points on any particular day during unrestricted routine daily activities, whereas home blood pressure (HBP) monitoring provides a lot of BP information obtained under fixed times and conditions over a long period of time, thus mean values of HBP provide high reproducibility, and thus an overall superiority compared with ABP.  2. HBP is at least equally or better able than ABP to predict hypertensive target organ damage and prognosis of cardiovascular disease.  3. HBPM allows for ongoing disease monitoring by patients, improves adherence to antihypertensive treatment, and can provide health-care providers with timely clinical data and direct and immediate feedback regarding diagnosis and treatment of hypertension.  4. HBPM provides BP information in relation to time; that is, BP in the morning, in the evening and at night during sleep, and it is an essential tool for the diagnosis of white-coat and masked hypertension.  5. HBPM yields minimal alerting affects and no or minimal placebo effect, and can therefore distinguish small, but significant, serial changes in BP. It is thus the most practical method for monitoring BP in the day-to-day management of hypertension. 6. The superiority of HBPM over ABPM and clinic BPM is apparent from almost all practical and clinical research perspectives.

White-coat hypertension

1. Numerous studies have examined whether white-coat hypertension (WCHT) is associated with increased cardiovascular risk, but with definitions of WCHT that were not sufficiently robust, results have been inconsistent. The aim of the present review was to standardize the evidence by only including studies that used a definition of WCHT consistent with international guidelines. 2. Published studies were reviewed for data on vascular dysfunction, target organ damage, risk of future sustained hypertension and cardiovascular events. 3. White-coat hypertension has a population prevalence of approximately 15% and is associated with non-smoking and slightly elevated clinic blood pressure. Compared with normotensives, subjects with WCHT are at increased cardiovascular risk due to a higher prevalence of glucose dysregulation, increased left ventricular mass index and increased risk of future diabetes and hypertension. 4. In conclusion, management of a patient with WCHT should focus on cardiovascular risk factors, particularly glucose intolerance, not blood pressure alone.

Does home blood pressure allow for a better assessment of the white-coat effect than ambulatory blood pressure?

BACKGROUND

The difference between clinic and ambulatory blood pressure (BP) is a poor estimate of the true white-coat effect (WCE) measured with beat-to-beat recording.

METHOD

We investigated whether the difference between clinic and home BP (home WCE) was a better estimate of true WCE than ambulatory WCE. In 73 young hypertensives, ambulatory WCE was calculated as the difference between clinic BP and the mean of two 24-h BP recordings, and home WCE as the difference between clinic and home BP (HBP) measured over 6 months. All individuals underwent beat-to-beat BP monitoring with the Finometer. During the recording, a white-coat test (true WCE) and a public speaking test were performed.

RESULTS

Ambulatory WCE correlated with home WCE (P  <  0.001 for systolic and diastolic BPs). However, both surrogate WCEs were unrelated to true WCE (P  =  0.93/0.36 and P  =  0.11/0.36, respectively). True WCE correlated with the BP reaction to public speaking (P  <  0.001/P  <  0.001), whereas both surrogate WCEs were unrelated to the BP response to this test (all P  >  0.21). Individuals were divided into two groups according to whether BP response to the doctor's visit was above (WCH+) or below (WCH-) the median. WCH+ patients had similar clinic and ambulatory BPs to WCH- but showed a higher BP response to public speaking.

CONCLUSION

As previously observed for ambulatory WCE, home WCE does not reflect the true BP reaction to doctor's visit. BP response to psychosocial stressors is increased in individuals with hyperreactivity to doctor's measurement but not in individuals with white-coat hypertension identified with either ambulatory or HBP measurement.

Relationship between GFR and albuminuria in stage 1 hypertension

BACKGROUND AND OBJECTIVES

Whether glomerular hyperfiltration is implicated in the development of microalbuminuria in hypertension is not well known. This prospective study investigated the relationship between changes in GFR and microalbuminuria in hypertension.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study assessed 534 stage 1 hypertensive participants from the Hypertension and Ambulatory Recording Venetia Study (n=386 men) without microalbuminuria at baseline, who were recruited from 1990 to 1995 and followed for a median of 8.5 years. Mean age was 33.9±8.6 years and mean BP was 146.6±10.5/94.0±5.0 mmHg. Creatinine clearance and 24-hour urinary albumin were measured at study entry and end. Participants were defined as normofilterers (normo) or hyperfilterers (hyper) according to whether GFR was <150 or ≥150 ml/min per 1.73 m(2), respectively. Participants were divided into four groups based on GFR changes from baseline to follow-up end: normo→normo (n=395), normo→hyper (n=31), hyper→hyper (n=61), and hyper→normo (n=47).

RESULTS

Microalbuminuria progressively increased across the four groups and was 5.3% in normo→normo, 9.7% in normo→hyper, 16.4% in hyper→hyper, and 36.2% in hyper→normo (P<0.001). This association held true in a multivariable logistic regression in which several confounders, ambulatory BP, and other risk factors were taken into account (P<0.001). In particular, hyperfilterers whose GFR decreased to normal at study end had an adjusted odds ratio of 7.8 (95% confidence interval, 3.3-18.2) for development of microalbuminuria compared with participants with normal GFR throughout the study.

CONCLUSIONS

These data support the hypothesis for a parabolic association between GFR and urinary albumin in the early stage of hypertension.

Factors associated with glomerular hyperfiltration in the early stage of hypertension

BACKGROUND

Glomerular hyperfiltration predicts development of nephropathy in hypertension but the factors responsible for increased glomerular filtration rate (GFR) are not well known. Aim of this study was to examine which clinical variables influence GFR in the early stage of hypertension.

METHODS

Participants were 1,106 young-to-middle-age hypertensive adults with creatinine clearance >60 ml/min/1.73 m(2). Clinic and ambulatory blood pressures (BPs) were measured and the difference between clinic and 24-h systolic BP was defined as the white-coat effect (WCE). In 606 participants, 24-h urinary epinephrine and norepinephrine were also measured. Glomerular hyperfiltration, defined as a GFR ≥150 ml/min/1.73 m(2), was present in 201 subjects.

RESULTS

Patients' mean age was 33.1 ± 8.5 years and office BP was 146 ± 10.5/94 ± 5.0 mm Hg. In multivariable linear regression, significant predictors of GFR were younger age (P < 0.0001), male gender (P < 0.0001), 24-h systolic BP (P = 0.0001), body mass (P < 0.0001), WCE (P = 0.02), log-epinephrine (P = 0.01), and coffee use (P < 0.01). In a logistic model, independent predictors of glomerular hyperfiltration were obesity (odds ratio, 95% confidence interval = 6.1, 3.8-9.8), male gender (2.9, 1.8-4.9), age <33 years (2.1, 1.5-3.1), ambulatory hypertension (2.0, 1.4-3.0), WCE >15 mm Hg (1.6, 1.1-2.3), heavy coffee use (2.0, 1.1-3.8), and epinephrine >25 mcg/24 h (1.9, 1.2-3.1).

CONCLUSIONS

The novel finding of this study is that hyper-reactivity to stress, as determined by urinary epinephrine level and WCE, and coffee use contribute to determining glomerular hyperfiltration in the early stage of hypertension. Our data may help to identify a subset of patients with glomerular hyperfiltration, who may be at increased risk of chronic kidney disease and may benefit from antihypertensive treatment.

Appropriate Time Interval to Repeat Ambulatory Blood Pressure Monitoring in Patients With White-Coat Resistant Hypertension

Resistant hypertension is defined as uncontrolled office blood pressure, despite the use of ≥3 antihypertensive drugs. Ambulatory blood pressure monitoring (ABPM) is mandatory to diagnose 2 different groups, those with true and white-coat resistant hypertension. Patients are found to change categories between controlled/uncontrolled ambulatory pressures without changing their office blood pressures. In this way, ABPM should be periodically repeated. The aim of this study was to evaluate the most appropriate time interval to repeat ABPM to assure sustained blood pressure control in patients with white-coat resistant hypertension. This prospective study enrolled 198 patients (69% women; mean age: 68.9±9.9 years) diagnosed as white-coat resistant hypertension on ABPM. Patients were submitted to a second confirmatory examination 3 months later and repeated twice at 6-month intervals. Statistical analyses included Bland-Altman repeatability coefficients and multivariate logistic regression. Mean office blood pressure was 163±20/84±17 mm Hg, and mean 24-hour blood pressure was 118±8/66±7 mm Hg. White-coat resistant hypertension diagnosis presented a moderate reproducibility and was confirmed in 144 patients after 3 months. In the third and fourth ABPMs, 74% and 79% of patients sustained the diagnosis. In multivariate regression, a daytime systolic blood pressure ≤115 mm Hg in the confirmatory ABPM triplicated the chance of white-coat resistant hypertension status persistence after 1 year. In conclusion, a confirmatory ABPM is necessary after 3 months of the first white-coat–resistant hypertension diagnosis, and the procedure should be repeated at 6-month intervals, except in patients with daytime systolic blood pressure ≤115 mm Hg, in whom it may be repeated annually.

Reproducibility of white-coat and masked hypertension in ambulatory BP monitoring

BACKGROUND

White-coat hypertension and masked hypertension have clinical and prognostic consequences. However, reproducibility of these phenomena is unknown. We examined the reproducibility of the white-coat and masking effects with real-life ambulatory blood pressure monitoring (ABPM).

METHODS

In a retrospective analysis of a prospectively assembled ABPM database there were 196 subjects (age 58+/-16 years, 59% female, 73% treated for hypertension) who underwent repeat ABPM for standard clinical indications. White-coat hypertension (or isolated manual uncontrolled hypertension) was defined as normal (<135/85 mmHg) awake blood pressure (BP) and abnormal (>or=140/90 mmHg) manual BP. Masked hypertension (or isolated ambulatory uncontrolled hypertension) was defined as abnormal awake BP with normal manual BP.

RESULTS

Treated and untreated subjects had similar distribution among hypertension subgroups; 16% white-coat hypertension (in treated subjects, isolated manual uncontrolled hypertension), 13% masked hypertension (in treated subjects, isolated ambulatory uncontrolled hypertension), 59% uncontrolled hypertension, 12% normal blood pressure (or controlled hypertension). In the second session the prevalence of white-coat and masked hypertension increased. Of 31 subjects with white-coat hypertension in the first session 19 (61%) remained ambulatory normotensive in the second session, while 18 of 25 (72%) masked hypertensive subjects remained ambulatory hypertensive. The reproducibility of the systolic manual-awake blood pressure difference was not inferior to that of other ambulatory variables. In untreated subjects the reproducibility of white-coat hypertension, masked hypertension and the white-coat effect was even better.

CONCLUSION

In a real-life ABPM database, we found white-coat hypertension and the masking phenomenon to be reasonably reproducible, as compared to other BP variables.

How reliable is isolated clinical hypertension defined by a single 24-h ambulatory blood pressure monitoring?

BACKGROUND

Isolated clinical hypertension (ICH) is characterized by a persistently elevated clinic blood pressure in the presence of a normal day-time or 24-h ambulatory blood pressure (ABP). This definition is based on a single ABP monitoring (ABPM) and little attention has been focused on the reproducibility of this condition.

OBJECTIVE

To investigate the reliability of the criteria currently recommended by major hypertension guidelines to detect ICH based on a single 24-h ABPM session.

METHODS

A total of 611 never-treated grade 1 and 2 hypertensive patients (mean age 46 +/- 12 years) referred for the first time to our out-patient clinic, underwent repeated clinic blood pressure measurements, routine investigations, two 24-h periods of ABPM 1-4 weeks apart, cardiac and carotid ultrasound examinations. ABPM was always performed over a working day and the same daily activities were recommended during the two periods. ICH was diagnosed by the following criteria: (i) mean daytime values < 135/85 mmHg or (ii) mean 24-h blood pressure values < 125/80 mmHg during the first ABPM.

RESULTS

The overall prevalence of ICH was 7.1% according to criterion (i) and 5.4% according to criterion (ii). Twenty (46.6%) of the 43 patients with mean daytime blood pressure values < 135/85 mmHg during the first ABPM, exceeded this cut-off value during the second ABPM period. Twenty-two (66.6%) of the 33 patients with mean 24-h blood pressure values < 120/80 mmHg during the first ABPM did not confirm a normal blood pressure profile during the second ABPM recording. Cardiovascular involvement was significantly lower in subjects with persistent normal ABP compared to those with non-reproducible ICH pattern or sustained hypertensives.

CONCLUSIONS

These findings clearly indicate that: (i) the classification of ICH on the basis of a single ABPM, using the cut-offs suggested by major hypertension guidelines, has a limited short-term reproducibility and (ii) repeated ABPM recordings should be recommended to correctly diagnose patients with ICH and improve cardiovascular risk stratification.

Prevalence of masked uncontrolled and treated white-coat hypertension defined according to the average of morning and evening home blood pressure value: from the Japan Home versus Office Measurement Evaluation Study

OBJECTIVE

To evaluate the prevalence of masked uncontrolled and treated white-coat hypertension defined according to the average of morning and evening home blood pressure values.

METHODS

The study population consisted of 3303 essential hypertensive outpatients receiving antihypertensive treatment in Japan. Information on the characteristics of the patients was collected by a physician's self-administrated questionnaire. The office blood pressure value was calculated as the average of the four readings in two visits. All patients were asked to measure their blood pressure once every morning and once every evening. In the study, we included patients with at least three measurements in the morning and in the evening, respectively. The average of all home blood pressure values was taken as the home blood pressure value.

RESULTS

The mean value of home systolic/diastolic blood pressure was 136.8/79.3 mmHg, and the mean value of office systolic/diastolic blood pressure was 142.8/80.6 mmHg. Of the 3303 patients, 758 (23.0%) had controlled hypertension (home <135/85 mmHg and office <140/90 mmHg), 628 (19.0%) had masked uncontrolled hypertension (home > or =135/85 mmHg and office <140/90 mmHg), 640 (19.4%) had treated white-coat hypertension (home <135/85 mmHg and office > or =140/90 mmHg), and 1277 (38.7%) had uncontrolled hypertension (home > or =135/85 mmHg and office > or =140/90 mmHg).

CONCLUSIONS

Treated white-coat hypertension and masked uncontrolled hypertension were often observed in clinical settings. Physicians need to understand the prevalence of such patients to prevent inadequate diagnosis and treatment in them.

White-coat hypertension: a clinical review

White-coat hypertension (WCHT), also called 'isolated office or clinic hypertension', is defined as the occurrence of blood pressure (BP) values higher than normal when measured in the medical environment, but within the normal range during daily life, usually defined as average daytime ambulatory BP (ABP) or home BP values (<135 mm Hg systolic and <85 mm Hg diastolic). The prevalence of WCHT varies from 15% to over 50% of all patients with mildly elevated office BP (OBP) values. In untreated hypertensive patients, the probability of WCHT especially increases with female gender and a mildly elevated OBP level. The value of other possible determinants such as (non) smoking status, duration of hypertension, left ventricular mass, number of OBP measurements, educational level, etc. is less consistently shown. Although, for various reasons, studies evaluating the long-term effects of WCHT are not always easy to interpret, most data indicate that persons with WCHT have a worse or equal cardiovascular prognosis than normotensives, but a better one than those with sustained hypertension. WCHT is sometimes considered a prehypertensive state, but data on the long-term evolution of subjects with WCHT are scarce. Patients with WCHT and a high cardiovascular risk or proven target organ damage should be pharmacologically treated. Subjects with uncomplicated WCHT should probably not receive medical therapy, but a close follow-up, including regular assessment of other risk factors and measurement of OBP (every 6 months) and ABP (every 1 or 2 years), is warranted.

Relationship between ambulatory blood pressure and follow-up clinic blood pressure in elderly patients with systolic hypertension

BACKGROUND

Patients with elevated clinic blood pressure and normal ambulatory blood pressure have a better prognosis than patients with sustained ambulatory hypertension, and may not have to be treated with antihypertensive drugs. On the contrary, current guidelines emphasize repeated clinic blood pressure measurements for the initiation of antihypertensive therapy.

OBJECTIVE

To examine the relationship between ambulatory blood pressure at baseline and clinic blood pressure after 6 months of follow-up in untreated hypertensive patients, and the relationships of these pressures with the subsequent incidence of cardiovascular events.

METHODS

Patients who were > or = 60 years old, with systolic clinic blood pressure of 160-219 mmHg and diastolic pressure < 95 mmHg, participated in the Systolic Hypertension in Europe trial. The relationship between ambulatory blood pressure at baseline and clinic blood pressure after 6 months of follow-up was examined in 295 patients enrolled in the Ambulatory Blood Pressure Monitoring substudy and randomized to the placebo arm, and who were still on double-blind treatment and not taking other antihypertensive drugs after 6 months follow-up.

RESULTS

Age averaged 70 +/- 6 years, 41% were men, and baseline daytime ambulatory blood pressure was 152 +/- 16/84 +/- 10 mmHg; clinic blood pressure decreased from 173 +/- 10/86 +/- 6 mmHg at baseline to 163 +/- 20/85 +/- 9 mmHg at month 6. Systolic daytime ambulatory blood pressure at baseline and systolic clinic blood pressure at month 6 were considered normal if < 140 mmHg. Of the 74 patients with normal systolic daytime ambulatory blood pressure at baseline, only seven (9.5%) had a normal systolic clinic blood pressure during follow-up. Conversely, of the 24 patients with normal follow-up clinic blood pressure, only seven (29%) had a normal systolic daytime ambulatory blood pressure at baseline. The incidence of cardiovascular events beyond the 6-month visit was significantly related to baseline ambulatory blood pressure but not to follow-up clinic pressure.

CONCLUSIONS

Baseline daytime ambulatory blood pressure and follow-up clinic blood pressure do not identify the same patients for antihypertensive treatment. Baseline ambulatory pressure is a better predictor of cardiovascular events than follow-up clinic pressure.

White coat hypertension: understanding the concept and examining the significance

Because the concept of white coat hypertension is evolving, a variety of definitions appear in the literature. There has also been continuing debate as to whether white coat hypertension is a benign clinical condition or is associated with increased hypertensive complications. This paper summarizes and evaluates the literature on white coat effect/hypertension, with a focus on the following aspects of the concepts: (1) alternative definitions, (2) prevalence and predictors, (3) prognostic significance, and (4) implications for clinical practice. The evidence suggests that white coat hypertension is not a harmless phenomenon. It is frequently associated with increased target-organ damage and often coexists with other cardiovascular risk factors. The extent of the presence of other risk factors may determine the risks associated with white coat hypertension. It is important for clinicians to understand the concept, learn to diagnose it properly, and develop strategies for evaluating risk levels so that patients receive the proper treatment.

Too much of a good thing? A critique of overemphasis on the use of ambulatory blood pressure monitoring in clinical practice

Ambulatory blood pressure monitoring (ABPM) can be considered a major achievement in clinical medicine. However, its superiority over traditional clinical measurement has often been overemphasized in the literature. In both cross-sectional and longitudinal studies, ABPM has been compared with clinical blood pressure calculated from only a few readings taken over a short period of time. For reasons of costs and practicality, ABPM should not be considered as a routine test in the assessment of the hypertensive patient. Most patients with borderline hypertension or isolated clinical hypertension can be profitably assessed with multiple clinical readings and self-blood pressure monitoring. Patients with large short-term or long-term blood pressure oscillations appear as optimal candidates to ABPM. The many methodological problems associated with the use of this technique suggest that ABPM is performed only by experienced doctors.

Sympathetic neural mechanisms in white-coat hypertension

OBJECTIVES

This study planned to establish whether sympathetic hyperactivity exists in white-coat hypertension (WHT) in the clinical setting, relative to matched groups with normotension (NT) and untreated essential hypertension (EHT).

BACKGROUND

White-coat hypertension differs from EHT by the presence of normal ambulatory blood pressure. Sympathetic hyperactivity exists in patients with EHT in the clinical setting and is believed to contribute to the development of target organ damage. Similar organ damage has been reported in WHT, yet little is known about sympathetic neural activity in this condition.

METHODS

Using microneurography, we examined groups of 12 matched subjects with WHT, EHT and NT during the same clinical setting to quantify muscle sympathetic nerve activity as multiunit discharge (MSNA) and single units (s-MSNA).

RESULTS

The s-MSNA in WHT (54 +/- 4.2 impulses/100 beats) was greater (p < 0.05) than in NT (37 +/- 5.4 impulses/100 beats) despite similar age and body mass index (BMI). The EHT values of s-MSNA (73 +/- 5.2 impulses/100 beats) were significantly (p < 0.05) greater than in WHT despite similar age, BMI and blood pressure levels. The MSNA followed a similar trend. White-coat hypertension had a similar cardiac baroreceptor reflex sensitivity to NT, but this was impaired in EHT relative to both NT and WHT.

CONCLUSIONS

It was shown, in the clinical setting, that central sympathetic hyperactivity exists in WHT, albeit to a lesser degree than EHT. These findings suggest that WHT may not be entirely benign and that the observed sympathetic hyperactivity may be responsible for development of target organ damage in this group of patients.

Ambulatory blood pressure monitoring

End-organ damage associated with hypertension is more closely related to ambulatory blood pressure (ABP) than clinic or casual blood pressure measurements. ABP measurements give better prediction of clinical outcome than clinic or casual blood pressure measurements. The technique of ABP monitoring (ABPM) is specialised; validated monitors and appropriate quality control measures should be used. Interpretation of ABP profile should include mean daytime, night-time (sleep) and 24-hour measurements, and consideration of diary information and time of drug treatment. Reports may also include ABP "loads" (percentage area under the blood pressure curve above set limits) for daytime and night-time periods. Normal blood pressure values for adults are < 135/85 mmHg for daytime, < 120/75 mmHg for night-time, and < 130/80 mmHg for 24 hours. ABPM is indicated to exclude "white coat" hypertension and has a role in assessing apparent drug-resistant hypertension, symptomatic hypotension or hypertension, in the elderly, in hypertension in pregnancy, and to assess adequacy of control in patients at high risk of cardiovascular disease. White coat hypertension requires continued surveillance; patients who display this phenomenon may, in time, develop established hypertension. Appropriate use of ABPM may result in cost savings. Randomised controlled trials comparing management based on clinic or casual versus ABP measurements are needed.

Resistant hypertension

Recent clinical trials suggest that resistant hypertension is increasingly common. In the majority of patients, uncontrolled hypertension is due to persistent elevation of the systolic blood pressure. Older age and obesity are associated with poor blood pressure control. Other contributing factors include severity of the underlying hypertension and renal insufficiency. Poor patient adherence is thought be a common cause of medication resistance. Exogenous substances such as nonsteroidal anti-inflammatory drugs, oral contraceptives, and sympathomimetic agents can interfere with treatment. The prevalence of secondary causes of hypertension increases with age, especially atherosclerotic renal artery stenosis. Recent reports suggest that primary aldosteronism may be the most common secondary cause of hypertension. It should be considered in all patients with resistant hypertension. Effective treatment of resistant hypertension requires identification and reversal of contributing factors and/or secondary causes of hypertension. Pharmacologic therapy should utilize combination therapy, including a long-acting diuretic.

Self-monitoring of blood pressure should be used in clinical trials

The number of studies of the efficacy of drugs in hypertension and of their effects on morbidity and mortality continues to be large. Traditionally such studies were carried out by measuring the blood pressure (BP) in the office. Recently, there has been an increasing use of other approaches, such as self-measurement. The advantages of this technique may be the achievement of greater precision of measurement, explained by elimination of the white-coat effect, reduction in placebo effect and reduction in variability of BP. Some have even noted a greater reproducibility than using ambulatory BP monitoring. We now have available reference values and normal ranges for self-BP monitoring. The feasibility and the limitations of self-BP measurement are also known. Self-measurement allows multiple recordings of BP over the short term as well as over the long term. Moreover, the compliance of this technique is satisfying. The analysis of the data requires precise recommendations. One cannot refer to trough : peak ratio, which is used in ambulatory recordings. However, other methods of analysis such as evening BP : morning BP ratio or measures taken after taking treatment are useful. The number of subjects needed for a study is much smaller than in a study performed using office measurements for a similar or better statistical power. Such a method has a higher predictive value than clinic measurement both for study of end organ damage and for morbidity and mortality. Finally home measurement is much less costly. In conclusion, provided one uses validated equipment and if one follows recommendations for each measurement and for the succession of measurements, then self-measurement of BP at home seems a useful and practical tool for therapeutic trials.

Alterations of cardiac structure in patients with isolated office, ambulatory, or home hypertension: Data from the general population (Pressione Arteriose Monitorate E Loro Associazioni [PAMELA] Study)

BACKGROUND

The prevalence and clinical significance of isolated office (or white coat) hypertension is controversial, and population data are limited. We studied the prevalence of this condition and its association with echocardiographic left ventricular mass in the general population of the PAMELA (Pressione Arteriose Monitorate E Loro Associazioni) Study.

METHODS AND RESULTS

The study involved a large, randomized sample (n=3200) representative of the Monza (Milan) population, 25 to 74 years of age. Participants in the study (64% of the sample) underwent measurements of office, home, 24-hour ambulatory blood pressure, and echocardiography. Isolated office hypertension was defined as systolic or diastolic values >/=140 mm Hg or >/=90 mm Hg, respectively. Home and ambulatory normotension were defined according to criteria previously established from the PAMELA Study, for example, <132/83 mm Hg (systolic/diastolic) for home and 125/79 mm Hg for 24-hour average blood pressure. Treated hypertensive subjects were excluded from analysis that was made on a total of 1637 subjects. Depending on normotension being established on systolic or diastolic blood pressure measured at home or over 24 hours, the prevalence of isolated office hypertension ranged from 9% to 12%. In these subjects, left ventricular mass index was greater (P<0.01) than in subjects with normotension both in and outside the office. This was the case also for prevalence of left ventricular hypertrophy. Left ventricular mass index and hypertrophy were similarly greater in subjects found to have normal office but elevated home or ambulatory blood pressure ( approximately 10% of the population).

CONCLUSIONS

Isolated office hypertension has a noticeable prevalence in the population and is accompanied by structural cardiac alterations, suggesting that it is not an entirely harmless phenomenon. This is the case also for the opposite condition, that is, normal office but elevated home or ambulatory blood pressure, which implies that limiting blood pressure measurements to office values may not suffice in identification of subjects at risk.

Independent predictors of isolated clinic ('white-coat') hypertension

BACKGROUND

Hypertension guidelines recommend 24 h ambulatory blood pressure (ABP) monitoring in hypertensive subjects with suspected isolated clinic hypertension (ICH). However, the pre-test probability of ICH based on the distribution of its independent predictors has not yet been estimated in hypertensive subjects with mildly elevated blood pressure.

OBJECTIVE

To ascertain the independent predictors of ICH in mildly hypertensive subjects.

METHODS

In the setting of the HARVEST-PIUMA collaboration, we studied 1564 subjects with hypertension stage I. At entry, all subjects were untreated and all underwent ABP monitoring and echocardiography. Diabetes, hypertension grade > I, renal failure or previous cardiovascular morbid events were exclusion criteria. Clinic BP was 143/92 mmHg (SD 9/5) and 24 h ABP was 128/81 mmHg (SD 10/8).

RESULTS

Prevalence of ICH (daytime ABP < 130 mmHg systolic and 80 mmHg diastolic) was 10.4%. In a multivariate logistic regression analysis, sex (P = 0.002), smoking (P = 0.038) and clinic diastolic BP (P = 0.0002) were the sole independent predictors of ICH according to the following equation: Y = 2.6438 + 0.5128 x sex (0 = men; 1 = women) + 0.4543 x current smoking (0 = yes; 1 = no) - 0.0531 x clinic diastolic BP (mmHg) and P (probability of ICH) = exp(Y)/[1 + (exp(Y)]. Left ventricular (LV) mass at echocardiography was a further independent predictor (P = 0.002) of ICH according to the following equation: Y= 3.4343 + 0.4603 x sex + 0.5989 x current smoking - 0.0482 x clinic diastolic BP - 0.0312 x LV mass [g/height (m)2.7]. LV mass was greater (P < 0.01) in the group with ambulatory hypertension [42.3 g/height (m)2.7] than in that with ICH [39.2 g/height (m)2.7] and not dissimilar between the ICH group and a control group of 370 healthy normotensive subjects [38.1 g/height (m)2.7].

CONCLUSIONS

In untreated subjects with stage I hypertension, ICH is most frequent among women, nonsmokers and subjects with low clinic BP and smaller LV mass. These findings allow identification of subjects with indication to ABP monitoring because of suspected ICH.

[Evolution of white coat hypertension to sustained hypertension. One year follow-up by ambulatory blood pressure monitoring]

BACKGROUND

To analyse the evolution of the white coat hypertension (WCH) to sustained hypertension, by means of ambulatory blood pressure monitoring (ABPM) during the first year after its diagnosis.

SUBJECTS AND METHOD

A prospective study of cohorts was designed in La Orden Health Center of Huelva, Spain. 86 individuals divided in two groups: a) group not exposed (GNE): 43 voluntary normotensives, and b) group exposed (GE): 43 individuals with WCH, defined as the blood pressure was superior or above 140 and/or 90 mmHg, respectively, with a mean diurnal ABPM below 135 and 85 mmHg in both cases. A ABPM was performed (Spacelabs 90207) at the beginning of the study, after 6 months and after 12 months. The clinical and ambulatory blood pressure and the incidence of sustained hypertension by ABPM in the two groups were compared. Sustained hypertension was considered when the diurnal blood pressure was superior to 135 and/or 85 mmHg for SBP and DBP.

RESULTS

At the end of the study, 82 patients were evaluate. The incidence of hypertension at 6 months of follow-up was of 4,76% (CI, 0-26.9) in GNE and 19.04% (95% CI, 0-42,6) in GE (RR: 3.8; 95% CI, 0.86-16.9) (p = 0.052). At one year of follow-up the incidence of hypertension in GNE was of 9.8% (95% CI, 0.31-1) as opposed to 46.3% (95% CI, 20.5-72.1) in GE (RR: 4.63; CI, 1.7-12.4) (p = 0.001).

CONCLUSIONS

The patients with WCH present a higher incidence of hypertension as compared to the normotensives, after 12 months of our follow-up.

Response to antihypertensive therapy in older patients with sustained and nonsustained systolic hypertension. Systolic Hypertension in Europe (Syst-Eur) Trial Investigators

BACKGROUND

The goal of the present study was to assess the effect of antihypertensive therapy on clinic (CBP) and ambulatory (ABP) blood pressures, on ECG voltages, and on the incidence of stroke and cardiovascular events in older patients with sustained and nonsustained systolic hypertension.

METHODS AND RESULTS

Patients who were >/=60 years old, with systolic CBP of 160 to 219 mm Hg and diastolic CBP of <95 mm Hg, were randomized into the double-blind placebo-controlled Systolic Hypertension in Europe (Syst-Eur) Trial. Treatment consisted of nitrendipine, with the possible addition of enalapril, hydrochlorothiazide, or both. Patients enrolled in the Ambulatory Blood Pressure Monitoring Side Project were classified according to daytime systolic ABP into 1 of 3 subgroups: nonsustained hypertension (<140 mm Hg), mild sustained hypertension (140 to 159 mm Hg), and moderate sustained hypertension (>/=160 mm Hg). At baseline, patients with nonsustained hypertension had smaller ECG voltages (P<0.001) and, during follow-up, a lower incidence of stroke (P<0.05) and of cardiovascular complications (P=0.01) than other groups. Active treatment reduced ABP and CBP in patients with sustained hypertension but only CBP in patients with nonsustained hypertension (P<0.001). The influence of active treatment on ECG voltages (P<0.05) and on the incidence of stroke (P<0.05) and cardiovascular events (P=0.06) was more favorable than that of placebo only in patients with moderate sustained hypertension.

CONCLUSIONS

Patients with sustained hypertension had higher ECG voltages and rates of cardiovascular complications than did patients with nonsustained hypertension. The favorable effects of active treatment on these outcomes were only statistically significant in patients with moderate sustained hypertension.

Treatment of white coat hypertension

White coat hypertension has been defined as the persistent elevation of blood pressure at the clinic or office only. It usually implies that daily ambulatory blood pressure is normal. The accepted cutoff for normal daytime ambulatory blood pressure is 135/85 mm Hg. The prevalence of white coat hypertension is high and varies from 20% to 45%. It appears to be more frequent in women, older patients, and persons with mild hypertension. White coat hypertension should not be confused with the white coat effect. The white coat effect signifies the difference in blood pressure between the office and daytime ambulatory blood pressure and occurs in patients with white coat hypertension as well as in patients with sustained hypertension that is treated or untreated. White coat hypertension is a benign condition, and the incidence of target-organ damage or cardiovascular morbidity and death is not significantly different from that in normotensive persons. Pharmacologic treatment should be withheld; instead, treatment should consist of lifestyle modification, moderate salt restriction, weight reduction, regular exercise, smoking cessation, and correction of glucose and lipid abnormalities. In addition, semiannual or annual follow-up with ambulatory blood pressure monitoring is advised.

Importance of various methods of blood pressure measurement in clinical trials

Ambulatory blood pressure (ABP) monitoring and self-measurement of blood pressure (BP) are more reproducible than clinic BP measurement, minimize the white coat effect, and can reduce the sample size necessary to demonstrate the efficacy of a drug in clinical trials. For many years, the trough:peak ratio has been considered the key index for demonstrating the efficacy of antihypertensive agents. However, several potential problems are associated with the use of this index, and ABP monitoring makes it possible to examine changes in BP over the entire 24-hour period, not only at a preset time of peak effect and at the end of the dosing interval. The smoothness index provides more comprehensive information on the 24-hour BP control with treatment and avoids part of the problems encountered with the trough:peak ratio. One simple way to summarize the results of ABP monitoring in clinical trials is to provide the mean 24-hour BP difference from placebo and the BP decrease at trough. The numerous advantages summarized above make ABP monitoring an accepted method of BP measurement in hypertension therapy trials. Self-measurement of BP may be a valid and less expensive alternative to ABP monitoring.

Contemporary management of refractory hypertension

Refractory or resistant hypertension is conventionally defined as systolic or diastolic blood pressure that remains uncontrolled despite sustained therapy with at least three different classes of antihypertensive agents. Refractory hypertension is estimated to affect less than 5% of the general population with hypertension; however, its prevalence increases with increasing severity of blood pressure. Patients presenting with refractory hypertension usually have progressed from mild, to moderate, to severe hypertension because of lack of or inadequate treatment. Other common contributing factors include obesity, medical nonadherence, suboptimal medical regimens, excessive dietary salt ingestion, secondary forms of hypertension, sleep apnea, and ingestion of substances that interfere with treatment. Combination therapy that includes appropriate doses of a diuretic is recommended for treatment of refractory hypertension. Use of fixed-dose combinations enhances compliance through cost savings, more convenient dosing, and reduced pill burdens.