Clinical relevance of office underestimation of usual blood pressure in treated hypertension

The Progetto Ipertensione Umbria Monitoraggio Ambulatoriale (PIUMA) Study

BACKGROUND

the Progetto Ipertensione Umbria Monitoraggio Ambulatoriale (PIUMA) study is a prospective registry of morbidity and mortality in initially untreated patients with essential hypertension whose initial diagnostic evaluation included 24-hour ambulatory blood pressure monitoring according to a standardized protocol. The present article summarizes the main results of the PIUMA study.

METHODS

the PIUMA study is conducted in three Hospitals in Umbria, Central Italy. After their initial assessment at entry, patients are followed in the outpatient clinic of the referring hospital and in collaboration with their family doctors. Telephone interviews with patients and meetings with family doctors are periodically conducted to ascertain the incidence of major complications of hypertension.

RESULTS

the PIUMA study gave us a tremendous opportunity to investigate several aspects related to hypertension: (1) Cross sectional studies focused on the association between clinic and 24-hour ABP and organ damage; (2) Longitudinal studies focused on the association between 24-hour ABP and hypertensive organ damage at cardiac level and other levels with the subsequent incidence of major cardiovascular events and mortality; (3) Longitudinal studies exploring the prognostic impact of other risk factors in hypertensive patients (i.e., diabetes, dyslipidemia, atrial fibrillation, left ventricular dysfunction, etc). The PIUMA study provided the first ever evidence of the prognostic value of (a) 24-hour ambulatory blood pressure monitoring; (b) regression of echocardiographic left ventricular hypertrophy in hypertensive patients.

CONCLUSIONS

the PIUMA registry gave us an enormous opportunity for investigating several pathophysiologic, diagnostic and therapeutic aspects related to management of hypertensive patients. Some of our studies have been mentioned in several Hypertension Guidelines to support some specific statements.

How to Measure 24-hour Central Blood Pressure and Its Potential Clinical Implications

The evaluation of 24-hour central blood pressure (24h cBP) combines the cBP non-invasive assessment with the 24-h ambulatory BP measurement. The major strength of the 24-h cBP evaluation is the ability to assess the degree of circadian changes between central and peripheral BP, namely 24-h BP amplification. This allows an accurate quantification of the degree of spatial and temporal BP variability in each single individual. BP amplification depends from a number of factors, such as the interaction between pressure and flow pulsatile motions, vasomotor tone, arterial tapering and other physiological and anthropometrical determinants. The assessment of 24-h BP amplification, a relatively pressure-independent parameter, may be helpful in better refining the risk of organ damage and future CV events over traditional measures of office and 24-h brachial BP. Currently, only few devices enable the assessment of 24-h cBP. These devices are based on peripheral (brachial or radial) BP waveform detection, and reconstruction of central BP waveform through mathematical models. The estimation of 24-h cBP imputed from multivariate regression equations was also proposed. Clinical data are still scarce and, although suggesting a possible superiority of 24-h cBP over brachial BP in the association with markers of organ damage, they are limited by methodological and technical aspects. There is urgent need of a standardized methodology and rigorous validation protocols for the 24-h cBP assessment. The field of 24-h cBP measurement still requires significant advancements of scientific knowledge before its introduction into clinical practice.

Ambulatory blood pressure monitoring in the elderly

The incidence of hypertension is high in the elderly and is present in 2/3 of the patients older than 65 years. Prevalence can reach 90% in patients older than 80 years. The presence of isolated systolic hypertension (ISH) is characteristic of this population. However, the prevalence of hypertension by ambulatory blood pressure monitoring (ABPM) is not well known. In this study, we analyzed the special characteristics of hypertension in this population, giving special emphasis on ABPM readings.

Masked inefficacy of arterial hypertension treatment: prevalence and predictors

Aim.To assess the prevalence of masked inefficacy of arterial hypertension treatment (AH MTI) and its predictors in various clinical groups and for various blood pressure (BP) control strategies, in order to evaluate the true effectiveness of antihypertensive therapy (AHT).Material and methods.AHT effectiveness was assessed in two groups of the patients with Stage I-II AH (n=219 and n=39), by comparing the ratios of clinical (cl) to ambulatory (a) BP parameters. AH MTI was defined as elevated aBP and target clBP levels during AHT. The potential predictors of AH MTI included gender, age, body mass index (BMI), anamnestic data, frequency of the clinical visits to measure BP, quality of life (QoL) parameters (GWBQ questionnaire), circadian BP profile, orthostatic BP, and ECG signs of left ventricular hypertrophy (LVH).Results.AH MTI prevalence in Groups I and II was 11,0-15,7 % and 22,6-58,1 %, respectively, depending on the definition used. The groups were significantly different in terms of age, BMI, and QoL questionnaire III and VI domains. According to the regression analysis results, in Group I AH MTI was associated with QoL questionnaire II, V, and VI domains, baseline parameters of 24-hour BP monitoring, 24-hour systolic BP (SBP) variability, minimal daytime levels of mean BP, and metoprolol and atenolol therapy. In Group II, AH MTI was predicted by age, BMI, previously administered AHT, alcohol consumption, orthostatic SBP levels, Sokolow-Lyon index, Cornell voltage and Cornell product, Gubner index, and QoL questionnaire I, IV, and VI domains.Conclusion.AH MTI prevalence is associated with some baseline characteristics of the patients and the character of AHT. Due to regression to the mean, AH MTI prevalence could increase substantially when clBP parameters are measured more often.

Detection of masked hypertension and the 'mask effect' in patients with well-controlled office blood pressure

BACKGROUND

Masked hypertension (MH) is characterized by its hidden nature and poor prognosis. However, it is not practical to routinely recommend home or ambulatory blood pressure monitoring (HBP or AMBP) to all patients with apparently well-controlled BP. The purpose of this study is to present, within the group of patients with well-controlled office BP (OBP), the clinical predictors of MH and to evaluate the gap (ie, the `mask effect' (ME)) between OBP and HBP.

METHODS AND RESULTS

BP was measured at the outpatient clinic and at home in 1,019 treated hypertensive patients. Candidate predictors for MH were analyzed within 511 patients with well-controlled OBP (45.6% men, 57.1±9.0 years). Among them, the prevalence of MH was 20.9% (n=107). In the multivariate-adjusted analysis, the risk of MH increased with high serum fasting blood glucose level (odds ratio (OR) 1.009, 95% confidence interval (CI): 1.001-1.018, P=0.020), higher systolic OBP (OR 1.075, 95%CI 1.045-1.106, P<0.001), higher diastolic OBP (OR 1.045, 95%CI 1.007-1.084, P=0.019) and the number of antihypertensive medications (OR 1.320, 95%CI 1.113-1.804, P=0.021). Furthermore, systolic HBP correlated well with systolic OBP (r=0.351, P<0.001) and with the degree of systolic ME (r=-0.672, P<0.001).

CONCLUSIONS

To recognize MH, it is practical to investigate those patients who are taking multiple antihypertensive drugs and have a high OBP with a high FBG level. The term "ME" identifies MH more appropriately than the term "negative white-coat effect".

Blood pressure assessment in haemodialysis patients: comparison between pre-dialysis blood pressure and ambulatory blood pressure measurement

AIM

Hypertension is common in haemodialysis (HD) patients. Determining the most appropriate method of blood pressure (BP) measurement, representative of target organ damage, is still an issue. BP variations between pre- and post-HD treatment, or between on-dialysis day and off-dialysis day, are common. The aim of this study was to examine the possible differences between pre-HD office BP (OBP) levels, inter-HD (iHD) or HDday 24 h ambulatory BP measurement (ABPM) with 48 h ABPM, where the latter was considered the gold standard.

METHODS

163 HD patients were studied. BP was monitored consecutively for 48 h with a Takeda TM2421 device, then sub-analysed into two periods of 24 h: HD and iHD day. An average of 12 sessions pre-HD OBP measurements was determined.

RESULTS

OBP significantly overestimates systolic (SBP) and diastolic BP (DBP) when compared with 48 hABPM. SBP and DBP are significantly higher on iHD day than on HD day: 141.2 1 20.8 versus 137.9 1 20.9, and 77.1 1 11.1 versus 76.1 1 10.9 (P < 0.01). No differences of SBP night/day ratio were reported between 48 hABPM and iHD 24 h ABPM or HD 24 h ABPM. The highest correlations were reported between 48 h SBP/DBP with iHD or HD 24 h ABPM (r 2 = 0.95, P < 0.001), while the lowest between 48 h SBP/DBP and OBP (r 2 = 0.40,P < 0.01, r 2 = 0.12, P < 0.01). The narrowest limits of agreement using the Bland and Altman test were reported between 48 h SBP or DBP and 24 h iHD or HD day ABPM. Considering 48 h ABPM, 80.5% of patients had BP higher than the norm, compared with 61.7% of patients in the case of OBP (c2 = 13.28, P < 0.001). The sensibility for detecting hypertension for iHD day 24 h ABPM was 98.4%, with specificity of 90%. The sensibility of 24 h HDday ABPM was 90.3%, with specificity 96.6%. In the case of OBP, sensibility and specificity were considerably lower, that is, 72.6% and 83.3% respectively.

CONCLUSION

Significant differences are shown between OBP and 48 h ABPM in the recognition of a hypertensive state. OBP measurement has a lower sensibility and specificity than 24 h ABPM, which remains a valid alternative approach to 48 h ABPM in HD patients. Errors of OBP estimation should be taken into account, with possible negative impact on treatment strategies and epidemiology studies

Masked hypertension in diabetes mellitus: a potential risk

The prevalence and clinical significance of masked hypertension (MHT) in diabetics have infrequently been described. The authors assessed the association of MHT (defined using a clinic blood pressure [BP] <140/90 mm Hg and daytime ambulatory BP > or = 135/85 mm Hg) with microvascular and macrovascular end organ damage in 81 clinically normotensive Japanese diabetic persons. The prevalence of silent cerebral infarcts (SCIs), increased left ventricular mass, and albuminuria were evaluated. Of 81 patients, 38 (46.9%) were classified as having MHT and showed significantly more SCIs (mean +/- SE: 2.5+/-0.5 vs 1.1+/-0.2; P=.017), and more albuminuria (39% vs 16%; P=.025), but no increase in left ventricular mass index, than the normotensive persons in office and on ambulatory BP monitoring group. The prevalence of MHT in this diabetic population was high (47%). Diabetic patients with MHT showed evidence of brain and kidney damage. Hence, out-of-office monitoring of BP may be indicated in diabetics whose BP is normal in the clinic.

Reverse white-coat effect as an independent risk for left ventricular concentric hypertrophy in patients with treated essential hypertension

Recent studies have shown that the converse phenomenon of white-coat hypertension called 'reverse white-coat hypertension' or 'masked hypertension' is associated with poor cardiovascular prognosis. We assessed the hypothesis that this phenomenon may specifically influence left ventricular (LV) structure in treated hypertensive patients. A total of 272 outpatients (mean age, 65 years) with chronically treated essential hypertension and without remarkable white-coat effect were enrolled. Patients were classified into two groups according to office and daytime ambulatory systolic blood pressure (SBP); that is subjects without (Group 1: office SBP > or =daytime SBP, n=149) and with reverse white-coat effect (Group 2: office SBP<daytime SBP, n=123). LV mass index and relative wall thickness were echocardiographically determined. In all subjects, LV mass index and relative wall thickness were positively correlated with daytime and 24-h SBP, but not with office SBP. In addition, these two indices were inversely correlated with office--daytime SBP difference. LV mass index (136+/-31 and 115+/-28 g/m(2), mean+/-s.d.) and relative wall thickness (0.49+/-0.09 and 0.46+/-0.07) were significantly greater in Group 2 than in Group 1. As for LV geometric patterns, Group 2 had a significantly higher rate of concentric hypertrophy compared with Group 1 (48 and 28%). Multivariate analyses revealed that the presence of reverse white-coat effect was a predictor for LV concentric hypertrophy, independent of age, sex, hypertension duration, antihypertensive treatment and ambulatory blood pressure levels. Our findings demonstrate that reverse white-coat effect is an independent risk factor for LV hypertrophy, especially concentric hypertrophy, in treated hypertensive patients.

Isolated ambulatory hypertension and changes in target organ damage in treated hypertensive patients

Isolated ambulatory hypertension is a condition characterized by elevated ambulatory but normal clinic blood pressure (BP), and has been reported to be associated with increased cardiovascular risk in untreated subjects. However, little is known about the relationship between this condition and intermediate end points such as target organ damage (TOD) in treated hypertensives. We investigated the impact of isolated ambulatory hypertension on left ventricular hypertrophy (LVH) and microalbuminuria (MA) in a selected sample of treated nondiabetic hypertensives with effective and prolonged clinic BP control (BP<140/90 mmHg). Clinic BP measurements, routine diagnostic procedures, echocardiography and 24-h urine collection for MA, were undertaken in 80 patients (mean age 53+/-8 years) with essential hypertension attending our hospital outpatient centre at baseline and after an average follow-up of 30 months. At follow-up evaluation BP status was assessed by self-measurement of BP and ambulatory BP monitoring (ABPM). At the follow-up visit, 51 out of 80 patients (63.7%) reached a BP control according to ABP (average daytime BP<132/85 mmHg) criteria (group I) whereas the remaining 29 did not (group II); home BP was controlled (BP<135/85 mmHg) in all members of group I and in 86% of group II. In the overall study population, mean Sokolow voltage, LV mass index (LVMI) and urinary albumin excretion (UAE) decreased compared to baseline from 24.1+/-5.0 to 18.9+/-5.1 mm (P<0.05), 115.6+/-24.1 to 97.7+/-21.6 g/m(2) (P<0.01), 11.8+/-23.7 to 5.8+/-14.9 mg/24 h (P<0.05), respectively. The prevalence of ECG LVH, altered LV patterns and MA fell from 7.5 to 2.5% (P=NS), from 45 to 25 (P<0.01) and from 13.7 to 5.1% (P<0.05), respectively. However, when data were analysed separately for the two groups a significant decrease of echo LVH and MA was found only in patients with controlled ABP. LVMI and MA decreased from 117.1+/-23.1 to 95.9+/-22.1 g/m(2) (P<0.01) and 12.8+/-24.7 to 4.1+/-5.7 mg/24 h (P<0.05) in group I, and from 114.1+/-24.8 to 102.3+/-20.3 (P=NS) and 11.9+/-22.1 to 6.3+/-18.1 mg/24 h (P=NS) in group II. In conclusion, in the present study isolated ambulatory hypertension in treated patients is associated with a lack of regression in cardiac and extracardiac TOD, suggesting that a tight BP control throughout the 24 h plays a key role in lowering hypertension-induced structural and functional alterations at cardiac and renal level.

Isolated ambulatory hypertension is common in outpatients referred to a hypertension centre

The present investigation was aimed at determining the prevalence and the blood pressure (BP) profile of isolated ambulatory hypertension, defined as an elevated ambulatory BP with normal office blood pressure, in a series of 1488 consecutive outpatients referred for routine clinical evaluation of suspected or established arterial hypertension. All patients underwent both office BP (OBP) measurement by a physician and 24-h ambulatory blood pressure monitoring (ABPM). Using OBP values (cutoff for diagnosis of hypertension >/=140/90 mmHg) and daytime ABPM (cutoff for diagnosis of hypertension >/=135/85 mmHg), patients were classified into eight subgroups. In the whole series we found that, independent of treatment status, the prevalence of isolated ambulatory hypertension exceeded 10%. More importantly, 45.3% of individuals who presented with normal OBP values, showed elevated BP at ABPM. Night-time BP, 24-h pulse pressure, and BP variability were significantly higher in isolated ambulatory hypertensives than in normotensive or in white-coat hypertensive individuals. Therefore, isolated ambulatory hypertension is characterized by a blood pressure profile that is similar to that observed in sustained hypertension. These findings suggest that isolated ambulatory hypertension is very common and probably the indications for ABPM should be more extensive in outpatients referred to hypertensive centre.

'Reverse white-coat hypertension' in older hypertensives

OBJECTIVES

The role of ambulatory blood pressure monitoring (ABPM) in the elderly is unclear. This study has examined differences between clinic and ambulatory blood pressure (BP) in a large cohort of older hypertensives, with particular respect to the factors influencing the direction and magnitude of this difference.

DESIGN

The Second Australian National Blood Pressure Study (ANBP2) is a general practice-based randomized-outcome trial in 6083 older hypertensives treated with an angiotensin-converting enzyme (ACE) inhibitor or diuretic-based regimen. Before starting treatment a subset of 713 patients (age range 65-83 years) had a 'successful' 26-hour ambulatory blood pressure recording with a SpaceLabs 90207 recorder.

RESULTS

Average clinic BP (+/- SD) was 167 +/- 12/90 +/- 8 mmHg. Average daytime ambulatory BP was 157 +/- 15*/89 +/- 10* mmHg and night ambulatory BP was 137 +/- 16+/74 +/- 10+ mmHg (different from clinic BP: *P < 0.01;from daytime ambulatory BP: +P < 0.001). Twenty-one to 45% of all patients had higher daytime systolic or diastolic ambulatory BP than clinic readings, with smoking, previous treatment for hypertension and lower clinic BP being the main predictors of this 'reverse white-coat effect'.

CONCLUSIONS

Although mean daytime ambulatory blood pressures were lower than clinic readings in this large cohort of untreated older hypertensives, a substantial proportion showed the reverse of the so-called 'white-coat effect'. These findings identify the important role for ABPM in the elderly, not only for avoiding overtreatment in those with typical 'white-coat hypertension' but also for ensuring adequate treatment is given to those with the reverse of this phenomenon.

Control of blood pressure in the ambulatory setting

Control of blood pressure still relies on conventional office or clinical blood pressure measurement using mercury sphygmomanometry. However, it has long been known that office measurement, even when repeated, does not fully reflect usual blood pressure. The additional use of ambulatory devices for prolonged periods of blood pressure measurement is now clinically feasible. Previous research has indicated that ambulatory blood pressure measurement is better than office measurement at predicting individual cardiovascular risk. Guidelines for clinical use of ambulatory blood pressure measurement and for quality control of devices are available. Ambulatory measurement has revealed characteristics of circadian rhythm and variability that are promising with regard both to improving our understanding of the aetiology of high blood pressure and to individual risk assessment. Some of the latest developments in research on ambulatory blood pressure measurement are discussed.