Nocturnal blood pressure fall and metabolic syndrome score in patients with white coat hypertension. Blood Press Monit. 2008;13:251-256. [PMID: 18799949 DOI: 10.1097/MBP.0b013e32830719c0]

Risk of new-onset metabolic syndrome associated with white-coat and masked hypertension: data from a general population

AIM

In the Pressioni Arteriose Monitorate e Loro Associazioni (PAMELA) study, clinical and metabolic variables as well as office, home and ambulatory blood pressure (BP) values were simultaneously measured at baseline and after a 10-year follow-up. The study design allowed us to assess the value of selective and combined elevation of different BP phenotypes in predicting new-onset metabolic syndrome (MetS).

METHODS

The present analysis included 1182 participants without MetS at baseline, as defined by the APT III criteria. On the basis of office, 24-h ambulatory BP and home values, participants were divided into four groups: normal, white-coat hypertension (WCH), masked hypertension and sustained hypertension.

RESULTS

Compared with participants with in-office and out-of-office normal BP, a greater incidence of new-onset age-adjusted and sex-adjusted MetS was observed in WCH (OR = 1.75, CI 1.01-3.04, P = 0.0046), masked hypertension (OR = 2.58, CI 1.26-5.30; P = 0.009) and sustained hypertension (OR = 2.14, CI 1.20-3.79, P = 0.009)) when out-of-office BP was defined by ambulatory criteria. This was not the case when out-of-office BP was defined by home criteria, as only the WCH group showed a greater risk (OR 2.16, CI 1.28-3.63, P = 0.003). Similar findings were obtained for single components of the MetS such as abdominal obesity and hyperglycemia.

CONCLUSION

Our study provides evidence that either isolated or combined BP elevations identified by office/ambulatory measurements, carry an increased risk of new-onset MetS, whereas, only WCH is associated with a greater risk of incident MetS whenever BP phenotypes are identified by office/home measurements. In a clinical perspective, a comprehensive evaluation of BP status based on office/ambulatory measurements may improve diagnosis of new-onset MetS and activate measures for its prevention.

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.

Closer look at white-coat hypertension

This review aims to clarify novel concepts regarding the clinical and laboratory aspects of white-coat hypertension (WCHT). Recent studies on the clinical and biological implications of WCHT were compared with existing knowledge. Studies were included if the WCHT patients were defined according to the 2013 European Society of Hypertension guidelines, i.e., an office blood pressure (BP) of ≥ 140/90 mmHg, a home BP of ≤ 135/85 mmHg, and a mean 24-h ambulatory BP of ≤ 130/80 mmHg. WCHT studies published since 2000 were selected, although a few studies performed before 2000 were used for comparative purposes. True WCHT was defined as normal ABPM and home BP readings, and partial WCHT was defined as an abnormality in one of these two readings. The reported prevalence of WCHT was 15%-45%. The incidence of WCHT tended to be higher in females and in non-smokers. Compared with normotensive (NT) patients, WCHT was associated with a higher left ventricular mass index, higher lipid levels, impaired fasting glucose, and decreased arterial compliance. The circadian rhythm in WCHT patients was more variable than in NT patient’s, with a higher pulse pressure and non-dipping characteristics. Compared with sustained hypertension patients, WCHT patients have a better 10-year prognosis; compared with NT patients, WCHT patients have a similar stroke risk, but receive more frequent drug treatment. There are conflicting results regarding WCHT and markers of endothelial damage, oxidative stress and inflammation, and the data imply that WCHT patients may have a worse prognosis. Nitric oxide levels are lower, and oxidative stress parameters are higher in WCHT patients than in NT patients, whereas the antioxidant capacity is lower in WCHT patients than in NT patients. Clinicians should be aware of the risk factors associated with WCHT and patients should be closely monitored especially to identify target organ damage and metabolic syndrome.

Associations between nocturnal blood pressure dipping and the metabolic syndrome in high- vs. low-acculturated Mexican American women

BACKGROUND

Less nocturnal blood pressure (BP) dipping has been associated with greater odds for the metabolic syndrome (MetS), a constellation of risk factors associated with cardiovascular disease (CVD). Little work has examined this association in Hispanics, who have elevated rates of MetS, or investigated differences in this relationship by level of acculturation. The purpose of this study was to examine the association between BP dipping and MetS in Hispanic women and to determine if this association is moderated by acculturation status.

METHODS

Two hundred eighty-six Mexican American women underwent assessment of MetS components (BP, waist circumference, fasting glucose, high-density lipoprotein cholesterol, and triglycerides) and completed a 36-hour ambulatory BP monitoring protocol, during which systolic BP (SBP) and diastolic BP readings were obtained. Nocturnal BP dipping was calculated as the percentage difference between average daytime and nighttime BP. Acculturation was defined by the language (Spanish, English) in which participants preferred to complete study instruments.

RESULTS

Although no significant main effects for BP dipping or acculturation emerged for MetS, the SBP dipping by acculturation interaction was significantly related to MetS (P < 0.01). Simple slope analyses revealed that less SBP dipping related to greater odds of MetS in high-acculturated women, but SBP dipping and MetS were unrelated in low-acculturated women.

CONCLUSIONS

The strength of the association between BP dipping and CVD risk (as measured by MetS) appears to vary by acculturation in Hispanic women. Future studies should explore mechanisms behind the BP dipping and CVD risk association and relevant modifying factors.

The effect of zolpidem on sleep quality, stress status, and nondipping hypertension

OBJECTIVE

Poor sleep quality and stress status have previously been shown to be closely associated with higher activation of the sympathetic nervous system and to be independent predictors of nondipping hypertension. This study aimed to evaluate the effects of the non-hypotensive sedative zolpidem on sleep quality, stress status, and nondipping hypertension.

METHODS

A total of 103 nondippers were defined as poor or good sleepers by the Pittsburgh Sleep Quality Index. They were randomized to receive zolpidem or placebo treatment for 30 days. Stress status was assessed by the Perceived Stress Scale, and levels of epinephrine and norepinephrine were examined to investigate the underlying mechanisms.

RESULTS

Poor sleepers treated with zolpidem for 30 days showed significant improvements in sleep quality and stress levels (P<0.01). More nondippers were converted to dippers in the group of poor sleepers treated with zolpidem (11 of 22 patients, 50.0%) than in the placebo (2 of 23, 8.7%) (P<0.01). Epinephrine and norepinephrine levels were significantly reduced in poor sleepers treated with zolpidem (P<0.05).

CONCLUSION

The results of this study suggest that zolpidem can improve sleep quality and stress status, and can convert nondippers with poor sleep quality into dippers. It may be an option for treating nondipping hypertensive patients with poor sleep quality.

Effect of age on interdependence and hierarchy of cardiovascular risk factors in hypertensive patients

The prognostic significance, interdependence, and hierarchy of cardiovascular risk factors could evolve with advancing age. Our study reports on the interdependence among blood pressure (BP), other metabolic syndrome components, and high-sensitivity C-reactive protein according to age in hypertensive subjects. A total of 5,712 nondiabetic patients (50.1% men, age range 40 to 95 years) evaluated in outpatient hypertension clinics were included and divided into 5 age groups (age 40 to 49, 50 to 59, 60 to 69, 70 to 79, and >80 years). BP, evaluated by both office and 24-hour ambulatory BP monitoring, and the metabolic and inflammation parameters were determined after a ≥2-week drug washout period. The prevalence of the metabolic syndrome (Adult Treatment Panel III definition) remained stable across the age groups. We observed a stable or increased association between waist circumference and insulin resistance (Homeostasis Model of Assessment-Insulin Resistance index) and fasting plasma glucose. However, the association between waist circumference and ambulatory BP monitoring systolic BP (r(2) decrease from 9.9% to 1.0%, p <0.001), high-density lipoprotein cholesterol (r(2) decreased from 21% to 4.9%, p = 0.002), and triglyceride levels (r(2) decreased from 17.5% to 1.9%, p <0.001) decreased with age. High-sensitivity C-reactive protein correlated with all metabolic syndrome components in all age groups (p <0.001 for all). It became the strongest determinant of ambulatory BP monitoring systolic BP (p <0.001) and high-density lipoprotein cholesterol (p <0.05) in patients >80 years old. In contrast, its association with waist circumference markedly decreased. In conclusion, hypertension and dyslipidemia, but not fasting plasma glucose, dissociate from central obesity with advancing age. They are increasingly determined by low-grade inflammation, independently of central obesity. These changing associations might underlie the weakening of obesity as a cardiovascular risk factor in older persons.

Serum phosphate in white-coat hypertensive patients: focus on dipping status and metabolic syndrome

Recent studies indicate an association between serum phosphate levels and blood pressure in hypertensive patients. A growing body of evidence suggests that white-coat hypertension (WCH) is associated with target organ damage. Furthermore, metabolic syndrome (MS) and a non-dipping pattern are associated with increased cardiovascular risk. The purpose of this study was to explore the nocturnal blood pressure fall in patients with WCH according to their serum phosphate levels and number of MS components fulfilled. The study included 2600 patients with WCH who attended our outpatient clinics. All patients underwent repeated office blood pressure measurements, 24-h ambulatory blood pressure monitoring and full clinical and laboratory evaluation. The diagnosis of MS was made according to the Adult Treatment Panel III criteria. Dipping pattern was defined as follows: 'dippers' had a nocturnal systolic blood pressure (NSBP) fall > or =10% but <20%; 'non-dippers' had an NSBP fall <10%; 'extreme dippers' had an NSBP fall > or =20% and 'reverse dippers' had an NSBP increase. There were 314 extreme dippers, 1337 dippers, 734 non-dippers and 116 reverse dippers. Reverse dippers presented with significantly lower levels of serum phosphate, whereas extreme dippers had significantly higher levels (3.39+/-3.29 vs. 3.58+/-3.52 mg per 100 ml, P<0.0001). The patients were classified according to the number of MS components and the main observation was the inverse relationship of serum phosphate with MS components (3.53+/-0.36, 3.50+/-0.38, 3.49+/-0.38, 3.44+/-0.36 and 3.35+/-0.31 mg per 100 ml, respectively, P=0.003). Patients with WCH and low serum phosphate levels appear to have a higher incidence of a non-dipping NSBP profile and an impaired metabolic profile. This observation may be important for the stratification of the cardiovascular risk in WCH patients.

Ambulatory blood pressure monitoring in type 2 diabetes and metabolic syndrome: a review

We reviewed the literature on ambulatory blood pressure (BP) monitoring in type 2 diabetes mellitus (T2DM) (focusing on organ damage progression, prognosis, white coat hypertension, and masked hypertension) and metabolic syndrome (MetS). In the text we reported 21 articles about T2DM and 11 about MetS, part of which were included in meta-analyses. In T2DM, individual studies and meta-analyses indicate that 24-h pulse pressure and reduced night-time BP fall or reverse dipping predict organ damage progression, total cardiovascular events and all-cause mortality. Moreover, white coat hypertension seems to be less frequent in T2DM and its impact on cardiovascular complications remains controversial. In contrast, masked hypertension is more frequent in T2DM and seems to be associated with increased organ damage. Some studies reported higher ambulatory BP in patients with MetS, but these patients were older and had higher clinical BP than those without MetS. With regard to the circadian BP profile, contrasting data have been reported, although pooled data suggest a higher risk of nondipping in patients with MetS.

Association between white-coat effect and blunted dipping of nocturnal blood pressure

BACKGROUND

In this study, we assessed whether the white-coat effect (difference between office and daytime blood pressure (BP)) is associated with nondipping (absence of BP decrease at night).

METHODS

Data were available in 371 individuals of African descent from 74 families selected from a population-based hypertension register in the Seychelles Islands and in 295 Caucasian individuals randomly selected from a population-based study in Switzerland. We used standard multiple linear regression in the Swiss data and generalized estimating equations to account for familial correlations in the Seychelles data.

RESULTS

The prevalence of systolic and diastolic nondipping (<10% nocturnal BP decrease) and white-coat hypertension (WCH) was respectively 51, 46, and 4% in blacks and 33, 37, and 7% in whites. When white coat effect and nocturnal dipping were taken as continuous variables (mm Hg), systolic (SBP) and diastolic BP (DBP) dipping were associated inversely and independently with white-coat effect (P < 0.05) in both populations. Analogously, the difference between office and daytime heart rate was inversely associated with the difference between daytime and night-time heart rate in the two populations. These results did not change after adjustment for potential confounders.

CONCLUSIONS

The white-coat effect is associated with BP nondipping. The similar associations between office-daytime values and daytime-night-time values for both BP and heart rate suggest that the sympathetic nervous system might play a role. Our findings also further stress the interest, for clinicians, of assessing the presence of a white-coat effect as a means to further identify patients at increased cardiovascular risk and guide treatment accordingly.

Non-dipping pattern in ambulatory blood pressure monitoring is associated with metabolic abnormalities in a random sample of middle-aged subjects

A reduction in the blood pressure decline at night (<10% from daytime systolic blood pressure (SBP)) during 24-h ambulatory blood pressure monitoring (ABPM) ('non-dipping pattern') is associated with cardiovascular morbidity. Our aim was to evaluate whether ABPM characteristics are associated with metabolic abnormalities in subjects without known hypertension or type 2 diabetes mellitus (T2DM). This is a cross-sectional population-based study on middle-aged subjects (n=462). Two distinct definitions of metabolic syndrome (MetS) were used: National Cholesterol Education Program-Third Adult Treatment Panel (NCEP-ATPIII) and International Diabetes Federation (IDF) criteria. Results suggested that subjects characterized by non-dipping in 24 h ABPM were more obese (P=0.014). After adjustment for body mass index, age and sex, non-dippers had higher very-low-density lipoprotein (VLDL)-cholesterol (P=0.003), total (P=0.029)-and VLDL-triglycerides (P=0.026) and oral glucose tolerance test 2 h blood glucose (P=0.027) compared with dippers. Non-dipping status was more common among subjects with MetS (P< or =0.01), impaired glucose tolerance (IGT) (P<0.05) and in those with the combination of IGT-T2DM (P< or =0.01) than among those without these abnormalities. ABPM non-dipping status was an independent predictor of IGT in multivariate models (P<0.05). With respect to MetS components, high triglycerides (P< or =0.005) and low high density lipoprotein-cholesterol (P<0.05) were associated with a non-dipping pattern. The percentage decline in blood pressure from day to night decreased with the number of metabolic abnormalities (P=0.012). In conclusion, ABPM non-dipping status is an independent predictor of glucose intolerance. It is also associated with several other metabolic abnormalities. Whether non-dipping pattern is causally related to these metabolic aberrations remains to be explored in a future prospective follow-up of this cohort.