The white-coat effect is unrelated to the difference between clinic and daytime blood pressure and is associated with greater reactivity to public speaking

OBJECTIVE: To compare the blood pressure (BP) response to doctor's visit with the BP reaction to a psycho-social challenge and with the difference between clinic and daytime BP (DeltaC-D). SUBJECTS: We studied 64 young stage-1 hypertensive subjects and 33 normotensive controls. MAIN OUTCOME MEASURES: Relationship between direct and surrogate measure of white-coat effect (WCE) and assessment of BP response to public speaking in subjects with normal or increased reaction to BP measurement. METHODS: The responses to BP measurement by a doctor and to public speaking were assessed with beat-to-beat Finapres recording. DeltaC-D was calculated on the basis of two BP monitorings and used as a surrogate measure of WCE. RESULTS: BP and heart rate changes elicited by the visit were unrelated to DeltaC-D and were correlated to the changes caused by the speech test [P <0.001 for systolic BP (SBP), P = 0.01 for diastolic BP (DBP), and P <0.001 for heart rate]. Hypertensive subjects with SBP response to doctor's visit above the median (hyper-reactive) showed increased reactivity also to public speaking (61 +/- 15 mmHg), while those with BP response below the median (normo-reactive) had a response to the psycho-social challenge (40 +/- 21 mmHg, 0.001 versus hyper-reactive) similar to that of the normotensive controls (38 +/- 17 mmHg). Epinephrine urinary output was greater in the hyper-reactive than the normo-reactive subjects (23 versus 12 microg/24 h, = 0.01). The SBP response to public speaking was greater in the hypertensive subjects with higher systolic daytime BP than in those with lower daytime BP (55.3 +/- 20.9 versus 45.1 +/- 20.6 mmHg, = 0.046). CONCLUSIONS: Subjects with increased WCE have an exaggerated response also to psycho-social stimuli. Average daytime BP, which incorporates the BP reactions to many psycho-social triggers can, thus, not be taken as the basal BP of an individual. This helps explain why DeltaC-D does not reflect the true WCE.     

Atrial fibrillation is associated with increased central blood pressure and arterial stiffness

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice and beta blockers (BBs) are the drugs of choice for rate or rhythm control in these patients. The purpose of this study was to describe differences in arterial stiffness (AS), central blood pressure (cBP), and the role of BBs on cBP in patients with AF compared to healthy individuals. The authors included 76 patients with paroxysmal/persistent AF. Carotid‐femoral pulse wave velocity (PWV) and cBP were measured and compared with data from 75 healthy individuals. Patients with AF had higher PWV (8.0 m/s vs. 7.2 m/s, p < .001), central systolic blood pressure (cSBP) (118 mm Hg vs. 114 mm Hg, p = .033), central pulse pressure (cPP) (39 mm Hg vs. 37 mm Hg, p = .035) and lower pulse pressure amplification (PPA) (1.24 vs. 1.30, p = .015), without differences in peripheral blood pressure (pBP) and heart rate (HR). AF patients had significantly increased PWV (β= 0.500, p = .010, adjusted R² = 0.37) after adjustment for confounding factors. The use of BBs significantly reduced PPA (β = ‐0.059, p = .017, adjusted R² = 0.30). AF patients have higher PWV, cSBP, cPP, and lower PPA, compared to healthy patients. These findings support the role of AS in the development of AF. Use of BBs is related to a potential adverse effect on cBP.     

Moderately increased alcohol consumption is associated with higher pressure wave reflections and blood pressure in men

Background and aimsIncreased alcohol consumption has been associated with CVD risk. Subclinical arterial damage (SAD) precedes the onset of cardiovascular disease (CVD), and allows early identification and study of the pathophysiology of CVD. Reliable, noninvasive vascular biomarkers are available for the early detection of SAD and reclassification of CVD risk. To investigate the association of alcohol consumption with multiple SAD biomarkers and central hemodynamics in a large sample of Greek adults with CVD risk factors.Methods and resultsThis cross-sectional study was conducted with 938 participants (43.5% men) and collected data on SAD biomarkers, central hemodynamics, and dietary intake. Multiple linear regression analysis was performed according to sex after adjusting for several confounders. In men, alcohol consumption of 20–30 g/d was positively associated with mean, diastolic, and peripheral systolic blood pressure (BP). The consumption of >30 g/d was positively associated with the augmentation index. In women, no statistically significant associations were found between alcohol consumption and BP or SAD indices. No statistically significant associations were found between alcohol consumption and arterial compliance or distensibility in both sexes.ConclusionIn men even a small deviation from the current recommendation for alcohol consumption is associated with both higher BP indices and pressure wave reflections. The absence of association in women might be due to very low alcohol intake, even in the high consumption group. More studies are needed to verify our findings and establish the above associations in each sex.     

Rhinitis is associated with increased systolic blood pressure in men: a population-based study

An association between impaired lower respiratory function and cardiovascular risk factors, such as hypertension, is often reported but it is unknown whether there is a relationship between upper airway disorders and cardiovascular risk factors, despite evidence that upper and lower respiratory tract disorders are closely linked. Our objective was to assess whether rhinitis is associated with arterial blood pressure and hypertension. In a population-based study of 330 adults aged 28-56 years, as part of the European Community Respiratory Health Survey, rhinitis was assessed by means of a questionnaire, and cardiovascular data were obtained using a questionnaire and by measuring blood pressure. Systolic blood pressure (SBP) was higher in men with rhinitis than in men without rhinitis (130.6 +/- 12.7 mm Hg versus 123.5 +/- 13.9 mm Hg; p = 0.002), and it was still the case after adjustment for cardiovascular and respiratory confounding factors. Hypertension was more frequent in men with rhinitis than in men without rhinitis, even after multivariate adjustment (odds ratio = 2.6, 95% confidence interval = [1.14-5.91]). The observation of SBP levels according to whether men have no rhinitis, seasonal rhinitis, or perennial rhinitis was compatible with a dose-response relationship (p for trend = 0.02). In conclusion, rhinitis is strongly associated with SBP and hypertension in men. Blood pressure should be regularly checked in men with rhinitis.     

Time rate of blood pressure variation is associated with increased common carotid artery intima-media thickness

The extent of target-organ damage has been positively associated with the magnitude of blood pressure (BP) variability in essential hypertension. However, the clinical implications of the rate of BP changes have never been investigated. We evaluated the association between the rate of systolic BP (SBP) variation derived from ambulatory BP monitoring (ABPM) data analysis and the extent of common carotid artery (CCA) intima-media thickness (IMT) in normotensive (n=280) and in uncomplicated hypertensive subjects (n=234). The 24-hour rate of SBP variation was significantly (P<0.001) higher in hypertensive (0.608 mm Hg/min; 95% confidence interval [CI], 0.595 to 0.622) than in normotensive individuals (0.567 mm Hg/min; 95% CI, 0.555 to 0.578), even after adjusting for baseline characteristics, day-night BP changes, 24-hour heart rate (HR), SBP, and HR variability. In the entire group of patients, multiple linear regression models revealed independent determinants of CCA-IMT in the following rank order: age (P<0.001), 24-hour rate of SBP variation (P<0.001), male gender (P=0.004), cholesterol (P=0.009), and smoking (P=0.014). A 0.1 mm Hg/min increase in the 24-hour rate of SBP variation was associated to an increment of 0.029 mm (95% CI, 0.018 to 0.040) in CCA-IMT independent of BP and HR levels, BP and HR variability, and dipping status. The rate of SBP variation during the morning BP surge correlated independently (P<0.001) to larger CCA-IMT values after adjustment for baseline characteristics and other ABPM parameters. Thus, the rate of BP fluctuations is greater in hypertensive patients and correlates to increased CCA-IMT. This finding indicates that steeper BP variations may produce a greater stress on the vessel wall and consequently result in medial hypertrophy of the large arteries.     

Determinants of ambulatory blood pressure response to physical activity

OBJECTIVES: Previous studies reported that the association between physical activity, measured with a wrist-worn accelerometer, and ambulatory blood pressure is rather weak and that the inter-individual variation in the degree of association is high. The aim of the present study was to quantify the responses of ambulatory blood pressure (BP) and heart rate (HR) to physical activity, and to determine the effect of age, gender, body mass index, mean BP and HR level and the use of antihypertensive medication on these responses. PATIENTS AND METHODS: Twenty-seven subjects (24 hypertensive) underwent 24-h ambulatory monitoring of BP, HR and physical activity. Physical activity was measured with four accelerometers mounted on the trunk and legs. The daytime BP and HR responses to physical activity and the possible modulating effects of the various subject characteristics on these responses were estimated with Random Regression Models. RESULTS: Increasing physical activity from a very low level (e.g. watching television) to a moderate level (e.g. shopping) caused an average response of systolic blood pressure (SBP) of 11.6 mmHg, of diastolic blood pressure (DBP) of 7.0 mmHg and of HR of 16.1 beats/min. The SBP response to activity was about 2 mmHg larger for the overweight subjects than for subjects with normal weight, and the SBP, DBP and HR responses increased about 0.8 mmHg, 0.6 mmHg and 0.7 beats/min, respectively, with every 10 years increase in age. The between-subjects variances in estimated responses were low and were almost completely explained by differences in overweight and age between subjects. The average within-subject variances, however, were high. CONCLUSIONS: Normal daily physical activity explains only a small part of the BP and HR variability. The BP and HR responses to activity are modestly affected by age. Overweight has a small effect on the SBP response to activity.     

Long-term changes in clinic blood pressure in patients with white-coat hypertension

BACKGROUND: White-coat hypertension, defined as hypertensive blood pressure values in a clinical setting but normal self-measured blood pressures, is relatively common among young patients but long-term spontaneous changes in clinic blood pressure in these patients with white-coat hypertension have not been assessed. DESIGN: A prospective study, with two clinical examinations (with a 5-year interval between the examinations).METHODS: We examined 188 male patients (mean age 16 years) with clinic blood pressures > 140/90 mmHg at baseline by determining clinic and home blood pressures, heart rates, heights and weights. These parameters were re-examined 5 years later. White-coat hypertension (n = 139) was defined as an average home blood pressure < 130/90 mmHg.RESULTS: A decrease in clinic systolic blood pressure to < 140 mmHg during the 5-yea follow-up was observed in 101 of the 139 patients with white-coat hypertension (73%) and 26 of the 49 patients with sustained hypertension (53%, P < 0.02). There was no difference between clinic heart rates and body mass indices at baseline of the patients who remained hypertensive in the clinic and those who became normotensive. Both the white-coat and the sustained hypertensive patients who remained hypertensive had higher baseline home blood pressures and an increase in body mass index during the 5-year period and maintained the baseline clinic heart rate, whereas those who became normotensive exhibited a reduction in clinic heart rate and maintained the baseline body mass indexd. The clinic systolic blood pressure at 5-year follow-up was correlated significantly to the clinic and home systolic blood pressures at baseline, the heart rate and body mass indexd at 5-year follow-up and the changes in bodyh mass index during the 5-year period. CONCLUSION: The prevalence of clinic systolic blood pressures < 140 mmHg during the 5-year period among patients with white-coat hypertension was higher than that among those with sustained hypertension. The clinic and home blood pressures at baseline and body mass indices and clinic heart rates at 5-year follow-up were related to the clinic systolic blood pressures at 5-year follow-up. These results suggest that control of body weight is important in the management both of young patients with white-coat hypertension and of those with sustained hypertension.     

Combined effect of blood pressure and physical activity on cardiovascular mortality

BACKGROUND: High blood pressure increases cardiovascular mortality, but whether the effect is counteracted by physical activity is not clear. METHODS: The combined association of blood pressure and physical activity on cardiovascular mortality was assessed in a cohort of 30 597 women and 30 508 men, using standardized blood pressure measurements and information on usual frequency, duration, and intensity of physical exercise. RESULTS: During 16 years of follow-up, 1942 women and 2824 men with no history of cardiovascular disease or diabetes, who had never used blood pressure medication, died from cardiovascular causes. Cardiovascular mortality increased continuously with increasing blood pressure, and, at each blood pressure level, risk was higher in men and women with no physical activity compared with those who reported high physical activity. High activity combined with increasing pressure, however, yielded higher risk than high activity combined with normotensive pressure. Compared with the reference (systolic pressure 120-129 mmHg and high activity), the relative risk of cardiovascular death for systolic pressure of 140-159 mmHg combined with high activity was 1.21 (95% confidence interval, 0.97-1.52), compared with a relative risk of 1.73 (95% confidence interval, 1.37-2.19) in men with no activity. For women, the corresponding relative risks were 1.47 (95% confidence interval, 1.04-2.09) in the high activity group and 1.93 (95% confidence interval, 1.39-2.69) for no activity. The combined results for diastolic pressure and physical activity displayed similar patterns. CONCLUSIONS: The results support the hypothesis that cardiovascular health of individuals with moderate hypertension will benefit from regular physical exercise.     

The return of increased blood pressure after discontinuation of antihypertensive treatment is associated with an impaired post-ischemic skin blood flow response

OBJECTIVE: To assess the post-ischemic skin blood flow response after withdrawal of antihypertensive therapy in hypertensive patients with normal blood pressure during treatment. DESIGN AND METHODS: Twenty hypertensive patients (group A) with a normal clinic blood pressure (<140/ 90 mmHg) receiving antihypertensive treatment (any monotherapy; one pill per day for at least 6 months) had their treatment discontinued. Before medication withdrawal and 2, 4, 12 and 24 weeks thereafter, the following measurements were made: clinic blood pressure, home blood pressure (three times per week, morning and evening) and skin blood flow response to a 5 min forearm arterial occlusion (using laser Doppler flowmetry). The patients were asked to perform an ambulatory blood pressure recording at any time if home blood pressure was > or =160/95 mmHg on two consecutive days, and treatment was initiated again, after determination of the skin hyperemic response, if daytime ambulatory blood pressure was > or =140/90 mmHg. The same studies were performed in 20 additional hypertensive individuals in whom antihypertensive treatment was not withdrawn (group B). The allocation of patients to groups A and B was random. RESULTS: The data fom 18 patients in group A who adhered strictly to the procedure were available for analysis. Seven of them had to start treatment again within the first 4 weeks of follow-up; four additional patients started treatment again during the next 8 weeks (group A1). The seven other patients remained untreated (group A2). The skin hyperemic response decreased significantly in patients in group A1 and returned to baseline values at the end of the study, when there were again receiving antihypertensive treatment. In patients in group A2 a significant attenuation of the hyperemic response was also observed. This impaired response was present even at the end of the 6 month follow-up, at which time the patients were still untreated but exhibited a significantly greater blood pressure than before drug discontinuation. The hyperemic response of patients who did not stop treatment (group B) did not change during the course of the study. CONCLUSIONS: Our findings show a decrease in the postischemic skin blood flow response after withdrawal of antihypertensive treatment in hypertensive patients. This impaired response may be due to the development of endothelial dysfunction, vascular remodeling, or both, and might contribute to the return of blood pressure to hypertensive values after withdrawal of antihypertensive therapy.     

Excess mortality associated with increased pulse pressure among middle-aged men and women is explained by high systolic blood pressure

OBJECTIVE: To assess the risk of death from coronary heart disease, stroke, all cardiovascular diseases and all-cause mortality associated with pulse pressure among the middle-aged population. METHODS AND DESIGN: A prospective 15-year follow-up cohort study was conducted of two independent cross-sectional random samples of the population who participated in baseline surveys in 1972 or 1977. Each survey included a self-administered questionnaire with questions on smoking and antihypertensive drug treatment, measurements of height, weight and blood pressure and the determination of the serum cholesterol concentration. Multivariate analyses were performed by using Cox proportional hazard models. SETTING: The provinces of North Karelia and Kuopio in eastern Finland PARTICIPANTS: Men and women aged 45-64 years with no history of myocardial infarction or stroke at the time of the baseline survey were selected. In total 4333 men and 5270 women took part in this follow-up study. RESULTS: The relative risk of coronary heart disease, stroke, cardiovascular disease and all-cause mortality increased with the increasing pulse pressure in individuals aged 45-64 years independent of the diastolic blood pressure level. Only in women with diastolic blood pressure > or = 95 mmHg was the relative risk of fatal stroke not statistically significant. After adjustment for systolic blood pressure, the positive association between mortality and increasing pulse pressure disappeared. CONCLUSION: Increasing pulse pressure is a predictor of death from coronary heart disease, stroke, cardiovascular disease and all causes in men and women aged 45-64 years, but the increase in risk is entirely associated with the increase in systolic blood pressure.     

Exaggerated blood pressure response to exercise is associated with inflammatory markers

PURPOSE: An exaggerated blood pressure (EBP) response to exercise has been shown to be a predictor of future hypertension and risk of cardiovascular mortality. Although EBP is associated with endothelial dysfunction and increased left ventricular hypertrophy, the underlying mechanisms are not fully understood. Inflammatory markers, C-reactive protein (CRP) and white blood cells (WBCs), were predictive of future hypertension. The objective of this study was to examine the hypothesis that increasing levels of CRP and WBCs would be related to an EBP response during exercise. METHODS: Inflammatory markers were compared in 43 males with an EBP (systolic blood pressure [SBP] >or=210 mm Hg) response during maximal treadmill testing to an age and resting SBP-matched group of 42 males with a normal blood pressure response to exercise. RESULTS: There were significant group differences in maximal SBP and diastolic blood pressure (DBP), exercise induced increases in SBP and DBP (P <.01), and WBCs (P <.01), but CRP did not differ between groups (P =.39). White blood cells were significantly associated with maximal SBP (r = 0.31), and the exercise-induced increase in SBP (r = 0.34). However, CRP did not correlate with the maximal blood pressure response to exercise (r = 0.11, P =.33). In a stepwise multiple regression analysis, WBC was independently associated with the exercise-induced increase in SBP (beta = 0.256, P =.011). CONCLUSIONS: These results suggest that inflammation may be associated with an EBP response during exercise testing.     

Nocturnal blood pressure decrease is associated with increased regional cerebral blood flow in patients with a history of ischemic stroke

BACKGROUND: It remains controversial whether there is a J-shaped relationship between blood pressure and recurrent stroke among patients with a recent history of ischemic stroke. OBJECTIVE: To investigate the relationship between regional cerebral blood flow (rCBF) and the dipping of nocturnal blood pressure in patients receiving antihypertensive treatment after ischemic stroke. METHODS AND RESULTS: Forty-seven patients with a previous history of ischemic stroke and 37 patients with a history of non-ischemic stroke underwent 24-h ambulatory blood pressure monitoring and rCBF measurement with single photon emission computed tomography. Of the 47 patients with ischemic stroke, 30 were diagnosed as having suffered atheromatous or embolic stroke, and 37 had an ischemic lesion in the territory of the carotid artery. Systolic and diastolic blood pressures during daytime and night-time were controlled at less than 140/90 mmHg by a low-salt diet or long-acting antihypertensive agents, or both. In patients with ischemic stroke, there were significant negative correlations between the percentage change in nocturnal blood pressure and rCBFs in the thalamus (r = -0.33, P = 0.02), putamen (r = -0.34, P = 0.02) and cerebral cortex (r = -0.31, P = 0.03). Multivariate analysis revealed that only the percentage change in nocturnal blood pressure was related to rCBF. There was a significant positive correlation between rCBFs in the thalamus and the cerebral cortex (r = 0.74, P < 0.05). In patients with non-ischemic stroke, there was no significant correlation between the percentage change in nocturnal blood pressure and rCBFs. CONCLUSIONS: These findings indicate that the decrease in nocturnal blood pressure is associated with the increase in rCBF in patients with a history of ischemic stroke in the territory of the carotid artery.     

Reactivity of ambulatory blood pressure to physical activity varies with time of day

Blood pressure (BP) fluctuates over a 24-hour period, but it is unclear to what extent this variation is governed completely by changes in physical activity. Our aim was to use a BP "reactivity index" to investigate whether the BP response to a given level of physical activity changes during a normal sleep-wake cycle. Hypertensive patients (n=440) underwent simultaneous 24-hour ambulatory BP, heart rate (HR), and activity monitoring. BP and HR were measured every 20 minutes. Actigraphy data were averaged over the 15 minutes that preceded a BP measurement. Individual BP and HR reactivity indices were calculated using least-squares regression for twelve 2-hour periods. These indices were then analyzed for time-of-day differences using a general linear model. Systolic BP and HR were generally more reactive to physical activity than diastolic BP. The highest reactivity of systolic BP (mean+/-SE=4+/-1 mm Hg per logged unit change in activity) was observed between 8:00 AM and 10:00 AM (P=0.014). Between 10:00 AM and 12:00 PM, BP reactivity then decreased (P=0.048) and showed a secondary rise in the early afternoon. These 24-hour changes in BP reactivity did not differ significantly between groups formed on the basis of early and late wake times (P=0.485), medication use, age, and sex (P>0.350). In conclusion, under conditions of normal living, the reactivity of BP and HR to a given unit change in activity is highest in the morning and shows a secondary rise in the afternoon.     

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.     

Identification of subjects with white-coat hypertension and persistently normal ambulatory blood pressure

OBJECTIVE: To assess the spontaneous changes in clinic blood pressure, ambulatory blood pressure (ABP) and left ventricular structure in untreated subjects with white-coat hypertension (WCH). DESIGN: A prospective observational study. PATIENTS AND METHODS: In 83 untreated subjects with WCH, 24 h non-invasive ABP monitoring and echocardiographic studies of the left ventricle were repeated after 0.5-6.5 years (mean 2.5) in the absence of antihypertensive drug treatment. WCH was defined by an average daytime ABP < 131/86 mmHg in women and < 136/87 mmHg in men. Ambulatory hypertension was defined by higher ABP values. RESULTS: In the whole population, the clinic blood pressure, ABP and left ventricular mass did not change from baseline to the follow-up visit, whereas the peak A: peak E ratio (where A is the velocity of transmitral blood flow after atrial contraction and E is the velocity during passive left ventricle filling) increased from 0.86 to 0.93. Sixty-three per cent of subjects remained in the WCH category at follow-up study; the remaining 37% shifted to the ambulatory hypertension category. The former group showed no changes in clinic blood pressure, ABP, left ventricular mass and peak A: peak E ratio. The clinic blood pressure of those who developed ambulatory hypertension did not change, whereas their ABP and peak A: peak E ratio increased and their left ventricular mass increased slightly but not significantly. The left ventricular mass increased from baseline to follow-up study by 6.2% in those who developed ambulatory hypertension and decreased by 1.6% in those who remained in the WCH category. The changes in left ventricular mass were associated with the changes in average 24 h systolic blood pressure, but not with the changes in clinic blood pressure. In a stepwise logistic regression analysis, average daytime diastolic blood pressure was the sole variable to enter the model and the probability of ambulatory hypertension at follow-up study was 20.0%percnt; in those with basal daytime ABP <130/80 mmHg, versus 81% in those with higher basal daytime blood pressure levels. CONCLUSION: After 0.5-6.5 years, WCH spontaneously evolved into ambulatory hypertension in 37% of subjects, with an accompanying rise in left ventricular mass. The probability of ambulatory hypertension increased with the baseline values of ABP, rather than with those of clinic blood pressure. WCH might be a prehypertensive state (particularly in subjects with higher baseline ABP levels) and should be defined by low levels of daytime ABP, possibly lower than 130/80 mmHg.