Magnitude of the early morning blood pressure surge in untreated hypertensive patients: a pooled analysis

The association between morning blood pressure and subclinical target organ damage in the normotensive population

OBJECTIVE

To investigate whether isolatedly elevated morning blood pressure (BP) is associated with subclinical target organ damage in normotensive individuals.

METHODS

In all, 287 normotensive individuals were included in this cross-sectional study. Each participant underwent anthropometric measurements, serum biochemistry evaluation, 24-h ambulatory BP monitoring, echocardiography, and carotid ultrasonography. The morning BP and morning surge were defined as: the average BP within 2 h after waking up, and the difference between the mean systolic BP (SBP) within 2 h after waking up and the mean SBP during the hour that included the lowest BP reading during sleep, respectively.

RESULTS

The prevalence of elevated morning BP was 37.3%. Individuals with elevated morning BP had higher left ventricular mass index and morning surge, and also mean 24-h, daytime, and night-time SBP and diastolic BP, BP variability (all P < 0.05). Left ventricular mass index was correlated with 24-h, daytime, night-time, and morning SBP, and morning surge (Pearson's correlation coefficients: 0.271, 0.262, 0.215, 0.368, and 0.415, respectively; all P < 0.05); and standard deviations of 24-h, daytime, and night-time SBP (Pearson's correlation coefficient: 0.303, 0.234, and 0.309, respectively), and coefficient of variations of 24-h and night-time SBP (Pearson's correlation coefficients: 0.253 and 0.271, respectively). Morning surge had the strongest correlation with left ventricular mass index in multiple regression analysis. Only daytime and morning SBP could discriminate elevated morning surge (≥35 mmHg), with an area under the curve of 0.744 and 0.864, respectively (both P < 0.01), and an optimal threshold of 121.5 mmHg for morning SBP.

CONCLUSION

Our findings suggest that isolated elevation of morning BP in normotensive individuals is associated with left ventricular hypertrophy. Home monitoring of morning BP may be suitable for detecting abnormal morning surge.

Ambulatory blood pressure monitoring and morning surge in blood pressure in adult black and white South Africans

We examined whether there were differences in the circadian variation in blood pressure and the morning surge in blood pressure between black and white Africans. Clinic and ambulatory blood pressure data obtained from the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study was examined (n = 406; 49% black African). Ambulatory blood pressure readings were fitted to a six-parameter double logistic equation to determine the power and rate of the morning surge in blood pressure. Multiple linear regression analysis was used to examine differences in blood pressure between black and white participants. Clinic and ambulatory blood pressure were higher in black participants throughout the day and night. In those taking medications, blood pressure was less well controlled in black subjects. Despite the higher systolic blood pressure, the day-night difference estimated by the logistic function was similar in black and white participants. However, the rate of rise and power in the morning surge in blood pressure was lower in black participants. We conclude that black participants of the SABPA study present with higher blood pressure throughout the day and night but have a lower power of the morning surge in blood pressure due to a slower morning rate of increase. Moreover, they had an increased prevalence of undiagnosed hypertension and, in those taking medication, were less likely to have their blood pressure controlled than their white counterparts.

Morning Blood Pressure Surge Relates to Autonomic Neural Activity in Young Non-Dipping Adults: The African-PREDICT Study

BACKGROUND

It is well established that an exaggerated morning blood pressure surge (MBPS) is associated with an increased risk for cardiovascular disease development in hypertensive individuals. However, in non-dipping individuals, a lower surge was reportedly associated with increased cardiovascular risk. Sympathetic nervous system activity is involved in 24-hour blood pressure fluctuations, including night-time dipping and the MBPS. To better understand this interaction, we investigated associations of MBPS with heart-rate variability and baroreceptor sensitivity in young healthy dippers and non-dippers.

METHODS

We included black and white men and women (n=827), aged 20-30 years and determined the MBPS using two formulas: the sleep-trough and dynamic morning surge. For autonomic function we determined baroreceptor sensitivity and heart-rate variability.

RESULTS

The majority of non-dippers in this population were black (70.4%), presenting lower sleep-trough and dynamic morning surge (all p<0.001). Heart-rate variability was comparable between dippers and non-dippers, whereas baroreceptor sensitivity was higher in non-dippers (p=0.021). Despite a suppressed MBPS profile in non-dippers, we found both sleep-trough (β=-0.25; p=0.039) and dynamic morning surge (β=-0.14; p=0.047) to be inversely and independently associated with 24-hour heart-rate variability (total power). These results were absent in dippers.

CONCLUSIONS

In conclusion, we found a higher night-time blood pressure coupled with lower MBPS in young healthy non-dippers. Furthermore, this lower MBPS was independently and negatively associated with autonomic neural activity, suggesting increased autonomic function involvement in MBPS suppression of non-dippers. The predictive value of suppressed nocturnal dipping pattern should be investigated while taking autonomic neural activity into account.

Morning blood pressure surge is associated with serum gamma-glutamyltransferase activity in essential hypertensive patients

The phenomenon that blood pressure rises sharply in the morning is called 'Morning Blood Pressure Surge' (MBPS). Serum gamma-glutamyltransferase (GGT) is a proinflammatory marker involved in the pathogenesis of cardiovascular diseases. Although both are novel cardiovascular risk factors associated with inflammation and atherosclerosis, the specific relationship between MBPS and serum GGT is unknown. This study investigates the relationship between MBPS and serum GGT activity in essential hypertensive patients. Totally, 320 hypertensive patients were recruited. Mean MBPS was 17.0 ± 12.9 mm Hg. MBPS was positively correlated with age (r = +0.222, P < 0.0001), body mass index (r = +0.132, P = 0.018), GGT (r = +0.271, P < 0.0001), daytime augmentation index adjusted for heart rate (AIx@75) (r = +0.140, P=0.014), 24-h pulse wave velocity (PWV) (r = +0.143, P = 0.014) and daytime PWV (r = +0.158, P = 0.007). From the 25th to 75th quartile of serum GGT, MBPS increased significantly (Ptrend < 0.0001). In multivariate linear regression analysis, MBPS was independently associated with age (P = 0.002), dipping status (P < 0.0001) and logGGT (P < 0.0001). In conclusion, MBPS is independently associated serum GGT activity in essential hypertensive patients. This is the first study in the literature to demonstrate an independent and a dose-response relationship between the two novel cardiovascular risk factors, MBPS and serum GGT, in this patient population.

Race, plasma renin activity, and morning blood pressure surge--results from the Dietary Approaches to Stop Hypertension trial

BACKGROUND

The association of preawake (difference between pre- and postwaking blood pressure (BP)) and sleep-through surge (difference between sleeping nadir and postwaking BP) with cardiovascular events is unclear. Examination of factors associated with surge may provide novel insights. We examined the association of race, which associates with nocturnal dipping, and plasma renin activity (PRA) with preawake and sleep-through surge among individuals on a controlled diet.

METHODS

We performed a post hoc analysis of 323 subjects from the Dietary Approaches to Stop Hypertension trial who had available 24-hour BP data and who ingested a control diet during a 3-week run-in period. Linear regression models were fit to estimate the association of race and PRA with preawake and sleep-through surge.

RESULTS

Of the 323 individuals, 55% were black, 53% were men, and the average age was 45 years. After controlling for other factors, black race was associated with a 3.2mm Hg lower preawake and a 3.7mm Hg lower sleep-through surge compared with nonblacks. In nonblacks, higher PRA was associated with greater preawake surge only. There was no association of PRA with either preawake or sleep-through surge in blacks. Additional adjustment for dipping status resulted in attenuation of the race-surge associations.

CONCLUSIONS

Black race is associated with lower preawake and sleep-through surge compared with nonblacks, but the effect is partially attenuated by dipping status. Higher PRA appears to be associated with a higher preawake surge in nonblacks only. Further research should address if morning surge is definitively associated with clinical outcomes in racial subgroups, independent of dipping.

Nonlinear mixed effects modeling of the diurnal blood pressure profile in a multiracial population

BACKGROUND

Cardiac and cerebrovascular events in hypertensive patients are related to specific features of the 24-hour diurnal blood pressure (BP) profile (i.e., daytime and nighttime BP, nocturnal dip (ND), and morning surge (MS)). This investigation aimed to characterize 24-hour diurnal systolic BP (SBP) with parameters that correlate directly with daytime and nighttime SBP, ND, and MS using nonlinear mixed effects modeling.

METHODS

Ambulatory 24-hour SBP measurements (ABPM) of 196 nontreated subjects from three ethnic groups were available. A population model was parameterized in NONMEM to estimate and evaluate the parameters baseline SBP (BSL), nadir (minimum SBP during the night), and change (SBP difference between day and night). Associations were tested between these parameters and patient-related factors to explain interindividual variability.

RESULTS

The diurnal SBP profile was adequately described as the sum of 2 cosine functions. The following typical values (interindividual variability) were found: BSL = 139 mm Hg (11%); nadir = 122 mm Hg (14%); change = 25 mm Hg (52%), and residual error = 12 mm Hg. The model parameters correlate well with daytime and nighttime SBP, ND, and MS (R (2) = 0.50-0.92). During covariate analysis, ethnicity was found to be associated with change; change was 40% higher in white Dutch subjects and 26.8% higher in South Asians than in blacks.

CONCLUSIONS

The developed population model allows simultaneous estimation of BSL, nadir, and change for all individuals in the investigated population, regardless of individual number of SBP measurements. Ethnicity was associated with change. The model provides a tool to evaluate and optimize the sampling frequency for 24-hour ABPM.

Relationship between self-reported sleep duration and changes in circadian blood pressure

BACKGROUND

Abnormalities in sleep duration and circadian blood pressure (BP) rhythm are both independently associated with increased risk of death and cardiovascular disease. The relationship, however, between these two entities remains unclear. This study was undertaken to determine whether abnormal sleep duration is associated with nondipping status and elevated morning surge.

METHODS

In a cross-sectional study, we assessed the relationship between self-reported sleep duration and circadian BP profiles from 24-h ambulatory BP monitoring (ABPM) in 108 normotensive and 417 hypertensive subjects, independent of relevant sociodemographic, anthropometric, and medical factors.

RESULTS

On average, subjects reported sleeping 6.5 +/- 1.7 h with 18.5% sleeping < or =5 h and 7.6%, > or =9 h. There were 199 (37.9%) nondippers in our cohort and the mean morning surge was 18.7 +/- 1.7 mm Hg. The adjusted odds ratio for nondipping (<10% nocturnal systolic BP fall) associated with a 1-h decrement in sleep duration was 1.12 (P = 0.04) and with age per 5-year increment, 1.15 (P = 0.0003). The adjusted odds ratio for an elevated morning surge (> or =18.0 mm Hg) associated with a 1-h increment in sleep duration was 1.13 (P = 0.02).

CONCLUSIONS

Our study indicates that a sleep deficit is associated with nondipping and a decreased morning surge, whereas a sleep surfeit is associated with less nondipping and an increased morning surge. These findings provide a possible link for the heightened risk of cardiovascular disease associated with disturbances in circadian BP rhythm and the extremes of sleep quantity.

Association of an abnormal blood glucose level and morning blood pressure surge in elderly subjects with hypertension

BACKGROUND

We previously reported that morning blood pressure (BP) surge (MBPS) was an independent risk factor for stroke. We evaluated the determinants of MBPS in hypertensive patients.

METHODS

We analyzed 24-h ambulatory BP monitoring (ABPM) records in 458 hypertensive patients (mean: 72.2 +/- 8.5 years). The MBPS was calculated as the mean systolic BP (SBP) over 2 h after waking minus mean SBP during the hour of sleep that included the lowest nighttime BP. The cutoff value for identifying the top decile (the MBPS group) was defined as > or =55 mm Hg.

RESULTS

The MBPS was associated with age, fasting plasma glucose, and 24-h SBP, and they were independent and significant determinants of MBPS in multivariate analysis (age, P = 0.01; fasting plasma glucose, P < 0.01; 24-h SBP, P = 0.04) after adjustment for confounding factors of gender, body mass index (BMI), and smoking status. The subjects in the MBPS group (n = 45) were older in age (76.4 years vs. 71.8 years, P < 0.01) and had higher fasting plasma glucose (97.6 mg/dl vs. 91.4 mg/dl, P = 0.04) than those in the non-MBPS group. In logistic regression analysis, the MBPS group was associated with older age (10 years older: odds ratio (OR) 1.85, 95% confidence interval (CI) 1.26-2.72, P < 0.01) and higher fasting plasma glucose (10-mg/dl increase: OR 1.16, 95% CI 1.01-1.33, P = 0.03).

CONCLUSION

In addition to older age and higher mean 24-h SBP, higher fasting plasma glucose was associated with MBPS.