Diagnostic value of electrocardiography and echocardiography for white coat hypertension in the elderly

Combination of Echocardiography and Pulse Wave Velocity Provides Clues for the Differentiation between White Coat Hypertension and Hypertension in Postmenopausal Women

OBJECTIVE

To determine whether or not noninvasive assessment of the cardiovascular system can discriminate white coat hypertension and hypertension in postmenopausal women. The major reason is the high prevalence of white coat hypertension in these subjects and the uncertain associations of white coat hypertension with cardiovascular risk.

PATIENTS AND METHODS

Selected women were required to be naturally or surgically menopausal for at least 1 year but not more than 5 years past their menstrual period. White coat hypertension patients were defined as subjects who had office blood pressures >150/90 mm Hg but who had both systolic and diastolic ambulatory pressures <120/80 mm Hg. In total, 44 subjects with a mean age of 52 years were recruited from the outpatient clinic and examined. Office and home blood pressures were measured using the HEM 401C (Omron Life Science Co. Ltd., Tokyo, Japan), a semi-automatic device that operates on the cuff-oscillometric principle and generates a digital display of the systolic (SBP) and diastolic blood pressure as well as the pulse rate. The pulse wave velocity (PWV) was recorded, and the left ventricular (LV) diameter, septal wall thickness, and left posterior wall thickness were assessed by M-mode echocardiography after selecting the measurement section by B-mode echocardiography.

RESULTS

Twenty patients were diagnosed as having white coat hypertension based on the criteria in the trial. Pulse wave patterns were different between subjects with white coat hypertension and those with hypertension. PWV of subjects with white coat hypertension was 1.32 ± 0.33 m/s and that of patients with hypertension was 1.46 ± 0.37 m/s (p < 0.01). In addition to these findings, there was a significant association between the values of home SBP and PWV and the LV mass index. However, this association was not seen for office SBP. When the data of the LV mass index and PWV were combined, white coat hypertension could be easily differentiated from hypertension.

CONCLUSIONS

The combination of blood pressure self-monitoring, echocardiographic data, and PWV can be a powerful indicator for the treatment of hypertension in postmenopausal women.

Pulse Wave Velocity in Postmenopausal Women

Cardiovascular disease (CVD) and osteoporosis are major causes of morbidity and mortality in postmenopausal women. The relationship between atherosclerosis and osteoporosis has been established by studies of the underlying pathophysiological mechanisms and biochemical pathways that seem to overlap in many places. Pulse wave velocity (PWV) is one of the known predictors of cardiovascular and all-cause mortality. Studies indicate that PWV in hypertensive postmenopausal women is increased, and hormone replacement therapy (HRT) attenuates this increase. In addition, recently, many studies have suggested a role for arterial stiffness in the association between CVD and osteoporosis. From these findings, it appears that estrogen deficiency combined with production of inflammatory cytokines plays a role in increased PWV closely associated with CVD and osteoporosis, although the mechanisms of arterial stiffness in postmenopausal women may be more complex. Accordingly, a possible role for PWV as a surrogate marker of CVD as well as osteoporosis in postmenopausal women is discussed in this review. First, menopause leads to increased arterial stiffness with aging in females. Further, epidemiological data evaluating arterial stiffness assessed by PWV provided evidence that most of the established CVD risk factors are determinants of PWV, and these risk factors are increased in patients with CVD. In turn, contrary to expectation, HRT did not always contribute to a lower incidence of CVD in postmenopausal women. By reviewing the current data available, it becomes clear that, at present, the effects of menopause including HRT on PWV remain controversial, and further studies are needed to clarify these associations.

White-coat hypertension in adults

White-coat hypertension is defined by the coexistence of persistently high office blood pressure (BP) with normal self-measured or ambulatory blood pressure. The prognostic impact of white-coat hypertension is a subject of debate. Cardiovascular morbidity seems to be lower in white-coat hypertension than in ambulatory hypertension, and, according to some but not all studies, is not dissimilar between white-coat hypertension and clinical normotension. In a large collaborative study including individual data from four prospective cohort studies, the incidence of stroke tended to increase in the white-coat hypertension group in the long run, crossing the hazard curve of the ambulatory hypertension by the ninth year of follow-up. These data raise the hypothesis, to be tested in future studies, that white-coat hypertension might not be a benign condition for stroke in the long term. Further studies are needed in order to: (1) test whether white-coat hypertension is really a benign condition for stroke in the long term; (2) compare, in patients with white-coat hypertension, a regimen based on life-style measures without drugs and a standard regimen consisting of life-style measures with the possible addition of drugs. On the basis of current evidence, it is reasonable to suggest a treatment based on life-style measures in the low-risk stratum of patients with white-coat hypertension under the conditions of correct definition, absence of comorbid conditions and target-organ damage, and adequate follow-up

Ambulatory blood pressure measurements

Ambulatory blood pressure monitoring (ABPM) has emerged as a valuable clinical and research tool in the assessment of pediatric hypertension. Large databases of 24-hour blood pressure monitorings in healthy children are under development for establishing normal reference values analogous to the Task Force data for casual blood pressure. In the clinical setting, pediatric studies using ABPM to evaluate elevated blood pressure have shown that the prevalence of white coat hypertension in children is similar to that reported in adults. Furthermore, 24-hour blood pressure parameters are correlated with hypertensive end-organ injury such as left ventricular hypertrophy. ABPM has allowed detailed assessment of circadian blood pressure patterns that show early subtle abnormalities in some high-risk groups and normal patterns in other groups previously thought to be at high risk. These studies will assist in the practice of evidence-based medicine regarding pediatric hypertension that will improve the long-term care that pediatricians provide to their patients.

White coat hypertension in children with elevated casual blood pressure

OBJECTIVE

We reviewed our experience using ambulatory blood pressure monitoring (ABPM) in children referred to a hypertension clinic to determine the frequency of pediatric white coat hypertension (WCH).

STUDY DESIGN

WCH was defined by 3 different diagnostic criteria: (1) mean 24-hour blood pressure (BP) less than Task Force-defined 95th percentile, (2) mean 24-hour BP less than 95th percentile from pediatric normative ABPM data, and (3) mean 24-hour BP less than ABPM 95th percentile and BP load (percentage of BP readings during 24-hour period exceeding the 95th percentile) less than 25%.

RESULTS

Clinic BP values were available in 67 otherwise healthy children who underwent ABPM; 51 had confirmed clinic hypertension by Task Force criteria. WCH frequency in these 51 patients with the stated criteria was 53%, 45%, and 22%, respectively. Elevated BP load was found in 52% (12/23) of patients with normal mean BP.

CONCLUSION

These results suggest that many children referred for casual BP elevation have WCH even by strict diagnostic criteria. ABPM may help differentiate WCH from persistent hypertension, thereby avoiding unnecessary diagnostic evaluation and identifying children most likely to benefit from early intervention.

White coat hypertension in children

Ambulatory blood pressure monitoring (ABPM) has become more widely used in the assessment of elevated blood pressure in children. The accurate diagnosis of white coat hypertension (WCH) is particularly important in children because detection of elevated blood pressure often results in expensive and invasive diagnostic procedures to detect underlying disease. Recent normative pediatric data have both enhanced our ability to interpret ABPM results in pediatric patients and increased awareness that children suffer from WCH as has already been reported in adults. The few studies of WCH in children report a prevalence ranging from 44-88%, depending on the choice of threshold values for normalcy. When persistent hypertension is confirmed by three blood pressure measurements on three different occasions, ABPM should be performed as part of the initial evaluation. If hypertension is confirmed by ABPM, further evaluation should be tailored to the individual patient depending on the age, severity of hypertension, associated risk factors, and presence of end-organ injury.

Prognostic value of ambulatory blood pressure : current evidence and clinical implications

This article is a critical review of the available evidence on the prognostic value of ambulatory blood pressure (ABP). Several event-based cohort studies have shown that ABP improves cardiovascular risk stratification over and beyond traditional risk factors, including office BP. Most of these studies have been conducted in subjects with essential hypertension who were untreated at the time of execution of ABP monitoring; other studies have been conducted in subjects who were poorly controlled with treatment or in the general population. In these studies, ABP was examined as a continuous variable or with operational risk categories. Cardiovascular risk showed a direct and independent association with the observed ABP (systolic, diastolic, and pulse) and an inverse association with the degree of BP reduction from day to night. Cardiovascular risk was also directly associated with the difference between the observed value of ABP and that predicted from the office BP. White-coat hypertension versus ambulatory hypertension and dippers versus nondippers are 2 classifications based on arbitrary operational risk categories. A blunted or absent BP reduction from day to night, defined with ABP as a continuous variable or with operational thresholds, was also associated with a worse outcome regardless of the average value of ABP during the 24 hours. Overall, these studies indicate that ABP monitoring is particularly valuable to refine cardiovascular risk stratification in untreated subjects with office hypertension and in those with resistant hypertension. Intervention studies targeted at ABP are now needed.

Is white coat hypertension associated with arterial disease or left ventricular hypertrophy?

Although white coat hypertension may be present in 20% or more of hypertensive individuals, its prognostic significance is unknown. We compared prognostically relevant measures of target-organ damage among 24 individuals with white coat hypertension and age- and sex-matched groups of sustained hypertensive and normotensive subjects classified by clinical and 24-hour ambulatory blood pressures. Left ventricular and carotid artery structure and function were evaluated by ultrasonography. Left ventricular mass index was similar in white coat hypertensive (82 +/- 17 g/m2) and normotensive (78 +/- 15 g/m2) subjects but was higher in sustained hypertensive subjects (97 +/- 19 g/m2, P < .02 and P < .002, respectively). Similarly, carotid artery intimal-medial thickness was greater in the sustained hypertensive group (0.98 +/- 0.21 mm) than in the white coat hypertensive (0.84 +/- 0.16 mm, P < .05) and normotensive (0.76 +/- 0.18 mm, P < .001) groups. The prevalence of discrete atherosclerotic plaques was higher in the sustained hypertensive group (58%) than in the white coat hypertensive (25%, P < .05) and normotensive (21%, P < .02) groups. Cardiac and carotid structure in individuals with white coat hypertension resemble findings in normotensive subjects and differ significantly from those in age- and sex-matched sustained hypertensive subjects. These findings suggest that white coat hypertension may be a benign condition for which pharmacological intervention may not be necessary, a hypothesis that needs to be tested in longitudinal studies with clinical end points.