[Prevalence of target organ damage and metabolic abnormalities in resistant hypertension]

The ability of baroreflex activation to improve blood pressure and resistance vessel function in spontaneously hypertensive rats is dependent on stimulation parameters

Baroreflex activation by electric stimulation of the carotid sinus (CS) effectively lowers blood pressure. However, the degree to which differences between stimulation protocols impinge on cardiovascular outcomes has not been defined. To address this, we examined the effects of short- and long-duration (SD and LD) CS stimulation on hemodynamic and vascular function in spontaneously hypertensive rats (SHRs). We fit animals with miniature electrical stimulators coupled to electrodes positioned around the left CS nerve that delivered intermittent 5/25 s ON/OFF (SD) or 20/20 s ON/OFF (LD) square pulses (1 ms, 3 V, 30 Hz) continuously applied for 48 h in conscious animals. A sham-operated control group was also studied. We measured mean arterial pressure (MAP), systolic blood pressure variability (SBPV), heart rate (HR), and heart rate variability (HRV) for 60 min before stimulation, 24 h into the protocol, and 60 min after stimulation had stopped. SD stimulation reversibly lowered MAP and HR during stimulation. LD stimulation evoked a decrease in MAP that was sustained even after stimulation was stopped. Neither SD nor LD had any effect on SBPV or HRV when recorded after stimulation, indicating no adaptation in autonomic activity. Both the contractile response to phenylephrine and the relaxation response to acetylcholine were increased in mesenteric resistance vessels isolated from LD-stimulated rats only. In conclusion, the ability of baroreflex activation to modulate hemodynamics and induce lasting vascular adaptation is critically dependent on the electrical parameters and duration of CS stimulation.

Prevalence and Clinical Characteristics of Refractory Hypertension

Background

We aimed to estimate the prevalence of refractory hypertension (RfH) and to determine the clinical differences between these patients and resistant hypertensives (RH). Secondly, we assessed the prevalence of white‐coat RfH and clinical differences between true‐ and white‐coat RfH patients.

Methods and Results

The present analysis was conducted on the Spanish Ambulatory Blood Pressure Monitoring Registry database containing 70 997 treated hypertensive patients. RH and RfH were defined by the presence of elevated office blood pressure (≥140 and/or 90 mm Hg) in patients treated with at least 3 (RH) and 5 (RfH) antihypertensive drugs. White‐coat RfH was defined by RfH with normal (<130/80 mm Hg) 24‐hour blood pressure. A total of 11.972 (16.9%) patients fulfilled the standard criteria of RH, and 955 (1.4%) were considered as having RfH. Compared with RH patients, those with RfH were younger, more frequently male, and after adjusting for age and sex, had increased prevalence of target organ damage, and previous cardiovascular disease. The prevalence of white coat RfH was lower than white‐coat RH (26.7% versus 37.1%, P<0.001). White‐coat RfH, in comparison with those with true RfH, showed a lower prevalence of both left ventricular hypertrophy (22% versus 29.7%; P=0.018) and microalbuminuria (28.3% versus 42.9%; P=0.047).

Conclusions

The prevalence of RfH was low and these patients had a greater cardiovascular risk profile compared with RH. One out of 4 patients with RfH have normal 24‐hour blood pressure and less target organ damage, thus indicating the important role of ambulatory blood pressure monitoring in guiding antihypertensive therapy in difficult‐to‐treat patients.

Resistant Hypertension

Conservatively, ten million people in the USA alone may suffer from RH and may be similarly prevalent elsewhere. Given the strong linear correlation between hypertension and cardiovascular outcomes, better control is paramount. We favor a multi-pronged approach. It may not suffice to address this by pharmacologic means only. Careful attention to modifiable risk factors, particularly sodium intake, adhering to a proper diet (i.e. DASH), and avoiding agents, i.e. non-steroidals, that can elevate the blood pressure, is key. Frequent follow up to establish the right treatment regimen and home blood pressuring monitoring can have a strong impact on control. Finally, consideration of device therapy may be a more viable option in the future.

Vascular Damage in Resistant Hypertension: TNF-Alpha Inhibition Effects on Endothelial Cells

Inflammatory cytokines have been associated with the pathophysiology of hypertension and target organ damage (TOD). Resistant hypertensive patients (RHTN) are characterized by poor blood pressure control and higher prevalence of TOD. This study evaluated the relationship between plasma levels of TNF-α and arterial stiffness (pulse wave velocity-PWV) in 32 RHTN and 19 normotensive subjects. Moreover, we investigated the effect of TNF-α inhibition on human endothelial cells (HUVECs) incubated with serum from RHTN and normotensive subjects. HUVECs containing serum obtained from normotensive (n = 8) and hypertensive (n = 8) individuals were treated with TNF-α inhibitor (infliximab). Cell suspensions were used for measurement of DNA fragmentation and reactive oxygen species (ROS) content. RHTN patients showed higher levels of TNF-α compared to normotensive subjects, as well as higher PWV. Positive correlation was found between TNF-α levels and PWV measures in the whole group. HUVECs incubated with serum from RHTN showed increased cell apoptosis and higher ROS content compared to normotensive subjects. Infliximab attenuated the apoptosis of HUVECs incubated with serum from RHTN, but no effect in ROS production was observed. Our findings suggest that TNF-α might mediate, at least in part, vascular damage in resistant hypertension.

[Resistant arterial hypertension in Primary Care patients in Spain. PRESCAP Study 2010]

OBJECTIVE

To determine the prevalence and clinical and epidemiological characteristics of Primary Care patients with resistant hypertension (RHT) in Spain.

PATIENTS AND METHODS

A cross-sectional multicenter study was conducted on hypertensive patients aged 18 or over and seen in a Primary Care clinic. RHT was considered as the presence of uncontrolled blood pressure in patients treated with at least 3 drugs, one of which is a diuretic.

RESULTS

Of the 12,961 hypertensive patients in the PRESCAP 2010 study, 962 (7.4%) fulfilled criteria for RHT, of whom 51% were women, and with a mean age (SD) 68.8 [11.4] years. Patients with RHT were older (68.80 [10.69] years vs. 66.06 [11.44] years, P<.001), had a higher prevalence of obesity (55.2 vs. 38.6%, P<.001), a higher waist circumference (103.90 [13.89] vs. 99.32 [13.69] cm, P<.001), and a higher prevalence of DM (48.3 vs. 29.5%, P<.001). The prevalence of target organ damage (73.0 vs. 61.4%, P<.001) and cardiovascular disease (46.7 vs. 26.8%, P<.001) were higher in patients with resistant hypertension. The multivariate analysis showed that the variables associated with resistant hypertension were the presence of cardiovascular disease, diabetes mellitus, sedentary life style, microalbuminuria, body mass index, duration of AHT, and triglycerides.

CONCLUSIONS

The prevalence of RHT in Primary Care patients is related to inappropriate lifestyles, the presence of target organ damage, and cardiovascular disease.

Resistant hypertension: demography and clinical characteristics in 6,292 patients in a primary health care setting

INTRODUCTION AND OBJECTIVES

The prevalence of resistant hypertension has recently been reported, but there are no studies on its demography. This study aimed to examine the demography and clinical characteristics of resistant hypertension in a large sample of primary care patients.

METHODS

A cross-sectional study was performed of all computerized medical records of hypertensive patients in Health Area 6 of Madrid (Spain). Of 63 167 hypertensive patients, we selected 48 744 with prescription of antihypertensive medication; of these, we selected those who met the American Heart Association criteria for resistant hypertension.

RESULTS

A total of 6292 patients had resistant hypertension, representing 9.9% of all hypertensive patients and 12.9% of those treated. A total of 5.5% were < 50 years (8.5% men and 3.2% women) and 24.7% were > 80 years (15.8% men and 31.4% women) (P < .001). In patients < 50 years, resistant hypertension was associated with male sex (odds ratio female/male = 0.006; 95% confidence interval, 0.000-0.042; P < .001), systolic blood pressure, obesity, stroke, and chronic kidney disease (P < .001). In those > 80 years, resistant hypertension was associated with female sex (odds ratio female/male = 1.27; 95% confidence interval, 1.08-1,10; P = .004), systolic blood pressure, diabetes mellitus, obesity, chronic kidney disease, coronary heart disease, and atrial fibrillation (P < .001). More than 50% of patients > 80 years with resistant hypertension had cardiovascular disease.

CONCLUSIONS

One in 4 patients with resistant hypertension is > 80 years. Resistant hypertension is associated with cardiovascular disease, age < 50 years in men and age > 80 years in women. There is a high proportion of cardiovascular disease in elderly patients with resistant hypertension.

[Blood pressure control in hospital units in Spain]

BACKGROUND AND OBJECTIVE

Blood pressure (BP) control has been extensively studied in patients attended in primary care but reports in the hospital setting, which includes referral units, are scarce. The aim was to evaluate the degree of BP control in hypertensive patients attended in referral units.

PATIENTS AND METHODS

We studied 1,550 hypertensive subjects (41.5% women) with a mean age of 64 (12) years, who were receiving antihypertensive drugs. The degree of BP control was estimated in a single visit by the proportion of patients with BP below 140/90 mm Hg.

RESULTS

BP was controlled in 653 patients (42%). In comparison, those whose BP was not controlled were more frequently women (odds ratio [OR] 1.57; 95% confidence interval [95%CI]: 1.23-1.99), obese (OR 1.28; 95%CI 1.00-1.63), smokers (OR 1.78; 95%CI 1.36-2.34), had left ventricular hypertrophy (OR 1.86; 95%CI 1.46-2.36) and elevated values of total serum cholesterol (OR 1.50; 95%CI 1.19-1.90) and triglycerides (OR 1.63; 95%CI 1.29-2.07). Therapeutical inertia was observed in 39% of uncontrolled patients. In a subgroup of patients who underwent ambulatory BP monitoring, discordance between measurements was only present in 23% (9.8 with isolated clinic hypertension and 13.1% with masked hypertension).

CONCLUSION

The degree of BP control in patients attended in referral units is estimated in 42% and has not been modified in the last decade. Although therapeutical effort and inertia have improved, this only compensates the increased risk and comorbidities of attended patients, making more difficult the control of BP values.

The white coat effect is not associated with additional increase of target organ damage in true resistant hypertension

BACKGROUND AND OBJECTIVE

White coat effect (WCE) (i.e., the difference between office blood pressure [OBP] and awake ambulatory blood pressure monitoring [ABPM]) may be present in hypertensive individuals. The relationship between occurrence of WCE and target organ damage (TOD) has not yet been assessed in true resistant hypertension (RHTN).

PATIENTS AND METHODS

RHTN patients were divided into two groups: RHTN with WCE (WCE, n=66) and RHTN without WCE (non-WCE, n=61). All patients were submitted to OBP measurement, ABPM, echocardiography and renal function evaluation in three visits.

RESULTS

No differences were observed between the WCE and non-WCE groups regarding age, body mass index or gender. OBP were 169.8±15.8/95.1±14.0 (WCE) and 161.9±9.0/90.1±10.4mmHg (non-WCE), ABPM=143.0±12.8/86.1±9.9 (WCE) and 146.1±13.6/85.1±14.9mmHg (non-WCE). No statistical differences were observed between WCE and non-WCE subgroups with respect to left ventricular mass index (LVMI) (WCE=131±4.7; non-WCE=125±2.9g/m(2)), creatinine clearance (WCE=78±4.7; non-WCE=80±3.6ml/min/m(2)) and microalbuminuria (MA) (WCE=44±8.4; non-WCE=49±6.8mg/g Cr).

CONCLUSIONS

This finding may suggest that WCE is not associated with additional increase of TOD in true RHTN subjects.