Sex-Related Disparities in Cardiovascular Outcomes Among Older Adults With Late-Onset Hypertension.

BACKGROUND: It is unclear whether sex-based differences in cardiovascular outcomes exist in late-onset hypertension. METHODS: This is a population-based cohort study in Ontario, Canada of 266 273 adults, aged ≥66 years with newly diagnosed hypertension. We determined the incidence of the primary composite cardiovascular outcome (myocardial infarction, stroke, and congestive heart failure), all-cause mortality, and cardiovascular death by sex using Cox proportional hazard models adjusted for demographic factors and comorbidities. RESULTS: The mean age of the total cohort was 74 years, and 135 531 (51%) were female. Over a median follow-up of 6.6 (4.7-9.0) years, females experienced a lower crude incidence rate (per 1000 person-years) than males for the primary composite cardiovascular outcome (287.3 versus 311.7), death (238.4 versus 251.4), and cardiovascular death (395.7 versus 439.6), P<0.001. The risk of primary composite cardiovascular outcome was lower among females (adjusted hazard ratio, 0.75 [95% CI, 0.73-0.76]; P<0.001) than in males. This was consistent after adjusting for the competing risk of all-cause death with a subdistributional hazard ratio, 0.88 ([95% CI, 0.86-0.91]; P<0.001). CONCLUSIONS: Females had a lower risk of cardiovascular outcomes compared with males within a population characterized by advanced age and new hypertension. Our results highlight that the severity of outcomes is influenced by sex in relation to the age at which hypertension is diagnosed. Further studies are required to identify sex-specific variations in the diagnosis and management of late-onset hypertension due to its high incidence in this group.

Potassium and Hypertension: A State-of-the-Art Review.

Hypertension is the single most important and modifiable risk factor for cardiovascular morbidity and mortality worldwide. Non pharmacologic interventions, in particular dietary modifications have been established to decrease blood pressure (BP) and hypertension related adverse cardiovascular events. Among those dietary modifications, sodium intake restriction dominates guidelines from professional organizations and has garnered the greatest attention from the mainstream media. Despite guidelines and media exhortations, dietary sodium intake globally has not noticeably changed over recent decades. Meanwhile, increasing dietary potassium intake has remained on the sidelines, despite similar BP-lowering effects. New research reveals a potential mechanism of action, with the elucidation of its effect on natriuresis via the potassium switch effect. Additionally, potassium-substituted salt has been shown to not only reduce BP, but also reduce the risk for stroke and cardiovascular mortality. With these data, we argue that the focus on dietary modification should shift from a sodium-focused to a sodium- and potassium-focused approach with an emphasis on intervention strategies which can easily be implemented into clinical practice.

Subclinical Primary Aldosteronism and Cardiovascular Health: A Population-Based Cohort Study.

BACKGROUND: Primary aldosteronism, characterized by overt renin-independent aldosterone production, is a common but underrecognized form of hypertension and cardiovascular disease. Growing evidence suggests that milder and subclinical forms of primary aldosteronism are highly prevalent, yet their contribution to cardiovascular disease is not well characterized. METHODS: This prospective study included 1284 participants between the ages of 40 and 69 years from the randomly sampled population-based CARTaGENE cohort (Québec, Canada). Regression models were used to analyze associations of aldosterone, renin, and the aldosterone-to-renin ratio with the following measures of cardiovascular health: arterial stiffness, assessed by central blood pressure (BP) and pulse wave velocity; adverse cardiac remodeling, captured by cardiac magnetic resonance imaging, including indexed maximum left atrial volume, left ventricular mass index, left ventricular remodeling index, and left ventricular hypertrophy; and incident hypertension. RESULTS: The mean (SD) age of participants was 54 (8) years and 51% were men. The mean (SD) systolic and diastolic BP were 123 (15) and 72 (10) mm Hg, respectively. At baseline, 736 participants (57%) had normal BP and 548 (43%) had hypertension. Higher aldosterone-to-renin ratio, indicative of renin-independent aldosteronism (ie, subclinical primary aldosteronism), was associated with increased arterial stiffness, including increased central BP and pulse wave velocity, along with adverse cardiac remodeling, including increased indexed maximum left atrial volume, left ventricular mass index, and left ventricular remodeling index (all P<0.05). Higher aldosterone-to-renin ratio was also associated with higher odds of left ventricular hypertrophy (odds ratio, 1.32 [95% CI, 1.002-1.73]) and higher odds of developing incident hypertension (odds ratio, 1.29 [95% CI, 1.03-1.62]). All the associations were consistent when assessing participants with normal BP in isolation and were independent of brachial BP. CONCLUSIONS: Independent of brachial BP, a biochemical phenotype of subclinical primary aldosteronism is negatively associated with cardiovascular health, including greater arterial stiffness, adverse cardiac remodeling, and incident hypertension.

Cardiac autonomic modulation in individuals with controlled and uncomplicated hypertension during exercise-heat stress.

TAKE-HOME MESSAGE: During short bouts of light-to-vigorous exercise in the heat, controlled and uncomplicated hypertension did not significantly modulate HRV in physically active individuals. These findings can be used to refine guidance on use of exercise for hypertension management in the heat.

Nonadherence Is Common in Patients With Apparent Resistant Hypertension: A Systematic Review and Meta-analysis.

BACKGROUND: The prevalence of medication nonadherence in the setting of resistant hypertension (RH) varies from 5% to 80% in the published literature. The aim of this systematic review was to establish the overall prevalence of nonadherence and evaluate the effect of the method of assessment on this estimate. METHODS: MEDLINE, EMBASE, Cochrane, CINAHL, and Web of Science (database inception to November 2020) were searched for relevant articles. We included studies including adults with a diagnosis of RH, with some measure of adherence. Details about the method of adherence assessment were independently extracted by 2 reviewers. Pooled analysis was performed using the random effects model and heterogeneity was explored with metaregression and subgroup analyses. The main outcome measured was the pooled prevalence of nonadherence and the prevalence using direct and indirect methods of assessment. RESULTS: Forty-two studies comprising 71,353 patients were included. The pooled prevalence of nonadherence was 37% (95% confidence interval [CI] 27%-47%) and lower for indirect methods (20%, 95% CI 11%-35%), than for direct methods (46%, 95% CI 40%-52%). The study-level metaregression suggested younger age and recent publication year as potential factors contributing to the heterogeneity. CONCLUSIONS: Indirect methods (pill counts or questionnaires) are insufficient for diagnosis of nonadherence, and report less than half the rates as direct methods (direct observed therapy or urine assays). The overall prevalence of nonadherence in apparent treatment RH is extremely high and necessitates a thorough evaluation of nonadherence in this setting.

Characterizing Hypertension Specialist Care in Canada: A National Survey.

Background: The hypertension specialist often receives referrals of patients with young-onset, severe, difficult-to-control hypertension, patients with hypertensive emergencies, and patients with secondary causes of hypertension. Specialist hypertension care compliments primary care for these complex patients and contributes to an overall hypertension control strategy. The objective of this study was to characterize hypertension centres and the practice patterns of Canadian hypertension specialists. Methods: Adult hypertension specialists across Canada were surveyed to describe hypertension centres and specialist practice in Canada, including the following: the patient population managed by hypertension specialists; details on how care is provided; practice pattern variations; and differences in access to specialized hypertension resources across the country. Results: The survey response rate was 73.5% from 25 hypertension centres. Most respondents were nephrologists and general internal medicine specialists. Hypertension centres saw between 50 and 2500 patients yearly. A mean of 17% (± 15%) of patients were referred from the emergency department and a mean of 52% (± 24%) were referred from primary care. Most centres had access to specialized testing (adrenal vein sampling, level 1 sleep studies, autonomic testing) and advanced therapies for resistant hypertension (renal denervation). Considerable heterogeneity was present in the target blood pressure in young people with low cardiovascular risk and in the diagnostic algorithms for investigating secondary causes of hypertension. Conclusions: These results summarize the current state of hypertension specialist care and highlight opportunities for further collaboration among hypertension specialists, including standardization of the approach to specialist care for patients with hypertension.

Contexte: Le spécialiste de l'hypertension reçoit souvent des patients orientés pour une hypertension sévère, d'apparition précoce et difficile à maîtriser, pour une urgence hypertensive ou pour des causes secondaires de l'hypertension. Les soins spécialisés de l'hypertension complètent les soins primaires pour ces cas complexes et font partie d'une stratégie globale de maîtrise de l'hypertension. Cette étude avait pour objectif de caractériser les centres de traitement de l'hypertension et les habitudes de pratique des spécialistes canadiens qui traitent l'hypertension. Méthodologie: Un sondage a été mené auprès de spécialistes de l'hypertension adulte de l'ensemble du Canada afin de décrire les centres de traitement de l'hypertension et la pratique des spécialistes au Canada, notamment les éléments suivants : la population de patients prise en charge par des spécialistes de l'hypertension, les renseignements sur la façon dont les soins sont prodigués, les variations dans les habitudes de pratique ainsi que les différences relatives à l'accès aux ressources spécialisées en hypertension à l'échelle du pays. Résultats: Le taux de réponse au sondage a été de 73,5 % dans 25 centres de l'hypertension. La plupart des répondants étaient des néphrologues et des spécialistes en médecine interne générale. Les centres de l'hypertension recevaient entre 50 et 2500 patients par année. En moyenne, 17 % (± 15 %) des patients provenaient du service des urgences et 52 % (± 24 %) provenaient d'une unité de soins primaires. La plupart des centres avaient accès à des tests spécialisés (prélèvements veineux surrénaliens, études du sommeil de niveau 1, tests autonomes) et à des traitements avancés pour l'hypertension résistante (dénervation rénale). Une hétérogénéité considérable a été constatée en ce qui concerne la pression artérielle cible chez les jeunes présentant un faible risque cardiovasculaire et les algorithmes diagnostiques pour étudier les causes secondaires de l'hypertension. Conclusions: Ces résultats résument la situation actuelle des soins spécialisés de l'hypertension et font ressortir des occasions d'accroître la collaboration entre les spécialistes de l'hypertension, notamment en ce qui concerne une normalisation de l'approche des soins spécialisés pour les patients hypertendus.

The effect of acute intradermal administration of ascorbate on heat loss responses in older adults with uncomplicated controlled hypertension.

NEW FINDINGS: What is the central question of this study? Does acute intradermal administration of the antioxidant ascorbate augment local forearm cutaneous vasodilatation and sweating via nitric oxide synthase (NOS)-dependent mechanisms during exercise-heat stress in older adults with uncomplicated controlled hypertension? What is the main finding and its importance? Relative to the control site, ascorbate had no effect on forearm cutaneous vascular conductance (CVC) and sweat rate, although CVC was reduced with NOS inhibition in older adults with hypertension. Acute local administration of ascorbate to forearm skin does not modulate heat loss responses during exercise-heat stress in older adults with hypertension. ABSTRACT: Nitric oxide synthase (NOS) contributes to the heat loss responses of cutaneous vasodilatation and sweating during exercise. However, the contribution of NOS may be attenuated in individuals with uncomplicated, controlled hypertension due to elevated oxidative stress, which can reduce NO bioavailability. We evaluated the hypothesis that the acute local intradermal administration of the antioxidant ascorbate would enhance cutaneous vasodilatation and sweating via NOS-dependent mechanisms during an exercise-heat stress in adults with hypertension. Habitually active adults who were normotensive (n = 14, 7 females, 62 ± 4 years) or had uncomplicated, controlled hypertension (n = 13, 6 females, 62 ± 5 years) performed 30 min of moderate-intensity (50% of their pre-determined peak oxygen uptake) semi-recumbent cycling in the heat (35°C, 20% relative humidity). Cutaneous vascular conductance (CVC) and sweat rate were assessed at four forearm skin sites continuously perfused with (1) lactated Ringer solution (Control), (2) 10 mM antioxidant ascorbate, (3) 10 mM NG -nitro-l-arginine methyl ester (l-NAME), a non-selective NOS inhibitor, or (4) a combination of ascorbate and l-NAME. Relative to Control, no effect of ascorbate was observed on CVC or sweating in either group (P = 0.619). However, l-NAME reduced CVC relative to Control in both groups (P ≤ 0.038). No effect of any treatment on sweating was observed (P ≥ 0.306). Thus, acute local administration of ascorbate to forearm skin does not enhance the activation of heat loss responses of cutaneous vasodilatation and sweating in older adults, and those with hypertension during an exercise-heat stress.

Influence of uncomplicated, controlled hypertension on local heat-induced vasodilation in nonglabrous skin across the body.

The objective of this study was 1) to examine pooled effects of hypertension on nitric oxide (NO)-dependent vasodilation during local heating across multiple nonglabrous skin regions, and 2) explore regional differences. Responses were compared between 14 participants with uncomplicated hypertension controlled with medication (7 females, 61 ± 6 yr) and 14 age-matched nonhypertensive controls (6 females; 60 ± 5 yr). Cutaneous vascular conductance, normalized to maximum vasodilation (%CVCmax), was assessed at the upper chest, abdomen, dorsal forearm, thigh, and lateral calf during local heating. Across all regions, local skin temperatures were simultaneously increased from 33°C to 42°C (1°C·10 s-1) and held until a stable heating plateau was achieved (∼40 min), followed by continuous infusion of 20 mM of NG-nitro-l-arginine methyl ester (l-NAME; ∼40 min) at all sites until a stable l-NAME plateau was achieved. The difference between heating and l-NAME plateaus was defined as the NO-contribution. Statistical equivalence for each heating phase was determined based on equivalence bounds of ±10%CVCmax for between-group differences. Pooled (all-regions) %CVCmax responses were equivalent for baseline (two one-sided t tests; P < 0.001), heating plateau (P = 0.002), l-NAME plateau (P = 0.028), and NO-contribution (P = 0.003). For individual regions, responses were equivalent at baseline for the abdomen, thigh, and calf, the heating plateau for the thigh, and the l-NAME plateau for the calf (all P < 0.05). Conversely, the calf heating plateau was lower in the hypertension group (t test; P < 0.05). Local heat-induced cutaneous vasodilation was statistically equivalent between individuals with uncomplicated, controlled hypertension, and nonhypertensive age-matched adults when pooled across multiple skin sites. Conversely, individual between-region comparisons were generally too variable to permit definitive conclusions.

Diet or additional supplement to increase potassium intake: protocol for an adaptive clinical trial.

BACKGROUND: High blood pressure is the leading cause of cardiovascular disease worldwide. The prevalence of high blood pressure is steadily rising as the population grows amongst older adults with the ageing population. Therapeutical treatments are widely available to decrease blood pressures, in addition to many lifestyle options, such as dietary changes and exercise. There is a marked preference amongst patients, as reiterated by Hypertension Canada, for more research into non-therapeutic methods for controlling blood pressure or to reduce the burden of taking many pills to control high blood pressure. Indeed, effective options do exist, especially with diet, specifically decreasing sodium and increasing potassium intake. Current public health outreach primarily focusses on sodium intake, even though potassium intake remains low in the Western world. Excellent data exist in published research that increasing potassium intake, either via dietary modification or supplements, reduces blood pressure and reduces risk of cardiovascular outcomes such as stroke. However, the advice most often provided by medical professionals is to 'eat more fruits and vegetables' which has little impact on patient outcomes. METHODS: We propose to do a clinical trial in two stages with an adaptive trial design. In the first stage, participants with high blood pressure and proven low potassium intake (measured on the basis of a 24-h urine collection) will get individually tailored dietary advice, reinforced by weekly supportive phone/email support. At 4 weeks, if there has not been a measured increase in potassium intake, participants will be prescribed an additional potassium supplement. Testing will be conducted again at 8 weeks, to confirm the efficacy of the potassium supplement. Final measurements will be planned at 52 weeks to observe and measure the persistence of the effect of diet or additional supplement. Concurrent measurements of sodium intake, blood pressure, participant satisfaction, and safety measures will also be done. DISCUSSION: The results of the study will help determine the most effective method of increasing potassium intake, thus reducing blood pressure and need for blood pressure-lowering medicines, and at the same time potentially increasing participant satisfaction. The current guidelines recommend changes in diet, not a potassium supplement, to increase potassium intake; hence, the two-stage design will only add supplements if the most rigorous dietary advice does not work. TRIAL REGISTRATION: This study has been registered on ClinicalTrials.gov NCT03809884 . Registered on January 18, 2019.

Blood pressure measurement: Should technique define targets?

Accurate assessment of blood pressure (BP) is the cornerstone of hypertension management. The objectives of this study were to quantify the effect of medical personnel presence during BP measurement by automated oscillometric BP (AOBP) and to compare resting office BP by AOBP to daytime average BP by 24-h ambulatory BP monitoring (ABPM). This study is a prospective randomized cross-over trial, conducted in a referral population. Patients underwent measurements of casual and resting office BP by AOBP. Resting BP was measured as either unattended (patient alone in the room during resting and measurements) or as partially attended (nurse present in the room during measurements) immediately prior to and after 24-h ABPM. The primary outcome was the effect of unattended 5-min rest preceding AOBP assessment as the difference between casual and resting BP measured by the Omron HEM 907XL. Ninety patients consented and 78 completed the study. The mean difference between the casual and Omron unattended systolic BP was 7.0 mm Hg (95% confidence interval [CI] 4.5, 9.5). There was no significant difference between partially attended and unattended resting office systolic BP. Resting office BP (attended and partially attended) underestimated daytime systolic BP load from 24-h ABPM. The presence or absence of medical personnel does not impact casual office BP which is higher than resting office AOBP. The requirement for unattended rest may be dropped if logistically challenging. Casual and resting office BP readings by AOBP do not capture the complexity of information provided by the 24-h ABPM.

Page kidney: Rare cause of acute kidney injury after complicated renal artery angioplasty.

The authors present a case of a patient who experienced a rare complication after attempted renal angioplasty and stenting, Page kidney. This patient presented with new onset hypertension secondary to bilateral renal artery stenosis and was referred for revascularization given hypertension refractory to medical management. The right renal artery underwent successful angioplasty and stenting; however, the left renal artery experienced recoil stenosis. Post-procedure the patient developed acute kidney injury secondary to Page kidney from subcapsular and extracapsular hematoma. This was managed conservatively with transfusions and the hematoma and acute kidney injury self-resolved over the next 4 months. This case highlights the importance of revascularization for refractory hypertension secondary to hemodynamically significant bilateral renal artery stenosis, the rare complication of Page kidney with attempted revascularization of renal artery stenosis and the involvement of a hypertension specialist in the decision of revascularization of renal artery stenosis.

Performance of the Aldosterone to Renin Ratio as a Screening Test for Primary Aldosteronism.

CONTEXT: The aldosterone to renin ratio (ARR) is the guideline-recommended screening test for primary aldosteronism. However, there are limited data in regard to the diagnostic performance of the ARR. OBJECTIVE: To evaluate the sensitivity and specificity of the ARR as a screening test for primary aldosteronism. METHODS: We searched the MEDLINE, Embase, and Cochrane databases until February 2020. Observational studies assessing ARR diagnostic performance as a screening test for primary aldosteronism were selected. To limit verification bias, only studies where dynamic confirmatory testing was implemented as a reference standard regardless of the ARR result were included. Study-level data were extracted and risk of bias and applicability were assessed using the QUADAS-2 tool. RESULTS: Ten studies, involving a total of 4110 participants, were included. Potential risk of bias related to patient selection was common and present in half of the included studies. The population base, ARR positivity threshold, laboratory assay, and reference standard for confirmatory testing varied substantially between studies. The reported ARR sensitivity and specificity varied widely with sensitivity ranging from 10% to 100% and specificity ranging from 70% to 100%. Notably, 3 of the 10 studies reported an ARR sensitivity of <50%, suggesting a limited ability of the ARR to adequately identify patients with primary aldosteronism. CONCLUSIONS: ARR performance varied widely based on patient population and diagnostic criteria, especially with respect to sensitivity. Therefore, no single ARR threshold for interpretation could be recommended. Limitations in accuracy and reliability of the ARR must be recognized in order to appropriately inform clinical decision-making.

Heat Tolerance and Occupational Heat Exposure Limits in Older Men with and without Type 2 Diabetes or Hypertension.

PURPOSE: To mitigate rises in core temperature >1°C, the American Conference of Governmental Industrial Hygienists (ACGIH) recommends upper limits for heat stress (action limit values [ALV]), defined by wet-bulb globe temperature (WBGT) and a worker's metabolic rate. However, these limits are based on data from young men and are assumed to be suitable for all workers, irrespective of age or health status. We therefore explored the effect of aging, type 2 diabetes (T2D), and hypertension (HTN) on tolerance to prolonged, moderate-intensity work above and below these limits. METHODS: Core temperature and heart rate were assessed in healthy, heat unacclimatized young (18-30 yr, n = 13) and older (50-70 yr) men (n = 14) and heat unacclimatized older men with T2D (n = 10) or HTN (n = 13) during moderate-intensity (metabolic rate: 200 W·m-2) walking for 180 min (or until termination) in environments above (28°C and 32°C WBGT) and below (16°C and 24°C WBGT) the ALV for continuous work at this intensity (25°C WBGT). RESULTS: Work tolerance in the 32°C WBGT was shorter in men with T2D (median [IQR]; 109 [91-173] min; P = 0.041) and HTN (120 [65-170] min; P = 0.010) compared with healthy older men (180 [133-180] min). However, aging, T2D, and HTN did not significantly influence (i) core temperature or heart rate reserve, irrespective of WBGT; (ii) the probability that core temperature exceeded recommended limits (>1°C) under the ALV; and (iii) work duration before core temperature exceeded recommended limits (>1°C) above the ALV. CONCLUSION: These findings demonstrate that T2D and HTN attenuate tolerance to uncompensable heat stress (32°C WBGT); however, these chronic diseases do not significantly impact thermal and cardiovascular strain, or the validity of ACIGH recommendations during moderate-intensity work.

Acute Severe Renal Artery Stenosis Presenting as Acute Kidney Injury With Severe Hypertension and Active Urine Sediment.

We present a case of severe renal artery stenosis that mimicked rapidly progressive glomerulonephritis with acute kidney injury, active urine sediments, and severe hypertension. Simultaneous presence of secondary hyperaldosteronism and hypokalemia prompted renal angiography and subsequent renal artery angioplasty and stenting, leading to rapid resolution of acute kidney injury, proteinuria, and hypertension. This case emphasises the importance and benefits of prompt diagnosis and revascularisation of acute severe renal artery stenosis in a patient with history of atherosclerotic renovascular disease presenting with sudden onset of severe hypertension and acute kidney injury with active urine sediment mimicking rapidly progressive glomerulonephritis.

Kidney, Cardiac, and Safety Outcomes Associated With α-Blockers in Patients With CKD: A Population-Based Cohort Study.

RATIONALE & OBJECTIVES: Alpha-blockers (ABs) are commonly prescribed for control of resistant or refractory hypertension in patients with and without chronic kidney disease (CKD). The association between AB use and kidney, cardiac, mortality, and safety-related outcomes in CKD remains unknown. STUDY DESIGN: Population-based retrospective cohort study. SETTINGS & PARTICIPANTS: Ontario (Canada) residents 66 years and older treated for hypertension in 2007 to 2015 without a prior prescription for an AB. EXPOSURES: New use of an AB versus new use of a non-AB blood pressure (BP)-lowering medication. OUTCOMES: 30% or greater estimated glomerular filtration rate (eGFR) decline; dialysis initiation or kidney transplantation (kidney replacement therapy); composite of acute myocardial infarction, coronary revascularization, congestive heart failure, or atrial fibrillation; safety (hypotension, syncope, falls, and fractures) events; and mortality. ANALYTICAL APPROACH: New users of ABs (doxazosin, terazosin, and prazosin) were matched to new users of non-ABs by a high dimensional propensity score. Cox proportional hazards and Fine and Gray models were used to examine the association of AB use with kidney, cardiac, mortality, and safety outcomes. Interactions by eGFR categories (≥90, 60-89, 30-59, and<30mL/min/1.73m2) were explored. RESULTS: Among 381,120 eligible individuals, 16,088 were dispensed ABs and matched 1:1 to non-AB users. AB use was associated with higher risk for≥30% eGFR decline (HR, 1.14; 95% CI, 1.08-1.21) and need for kidney replacement therapy (HR, 1.28; 95% CI, 1.13-1.44). eGFR level did not modify these associations, P interaction=0.3and 0.3, respectively. Conversely, AB use was associated with lower risk for cardiac events, which was also consistent across eGFR categories (HR, 0.92; 95% CI, 0.89-0.95; P interaction=0.1). AB use was also associated with lower mortality risk, but only among those with eGFR<60mL/min/1.73m2 (P interaction<0.001): HRs were 0.85 (95% CI, 0.78-0.93) and 0.71 (95% CI, 0.64-0.80) for eGFR of 30 to 59 and<30mL/min/1.73m2, respectively. LIMITATIONS: Observational design, BP measurement data unavailable. CONCLUSIONS: AB use in CKD is associated with higher risk for kidney disease progression but lower risk for cardiac events and mortality compared with alternative BP-lowering medications.

Impact of uncomplicated controlled hypertension on thermoregulation during exercise-heat stress.

Exercise is promoted for management of hypertension and as a general healthy behavior, but environmental conditions are seldom considered in these recommendations. Hypertension may affect skin blood flow and sweating, two of the primary mechanisms which prevent continued elevations in core temperature by facilitating whole-body heat loss during exercise-heat stress. We show that during incremental exercise-heat stress (in hot-dry conditions), controlled and uncomplicated hypertension is unlikely to exert a meaningful effect on whole-body heat loss in individuals who are already physically active.

Effects of CPAP on Blood Pressure and Sympathetic Activity in Patients With Diabetes Mellitus, Chronic Kidney Disease, and Resistant Hypertension.

BACKGROUND: Patients with obstructive sleep apnea (OSA) have increased sympathetic activity and frequently also have resistant hypertension (HTN). Treatment of OSA with continuous positive airway pressure (CPAP) decreases awake and sleep blood pressure (BP) and sympathetic activity. This study was designed to assess the effect of treatment of OSA with CPAP on sympathetic activity and BP in patients with diabetes mellitus (DM), chronic kidney disease (CKD), and resistant HTN. METHODS: This was a randomized, double-blind, sham-controlled trial. Patients with DM, CKD, and resistant HTN were randomized to treatment with a therapeutic or subtherapeutic CPAP for 6 weeks. They underwent 24-hour ambulatory BP monitoring and assessment of muscle sympathetic nerve activity before and after 6 weeks on treatment. RESULTS: Treatment with therapeutic CPAP caused significant decreases in awake systolic and diastolic BP from 144 to 136 mm Hg (P = 0.004) and from 79 to 74 mm Hg (P = 0.004) and in sleep BP from 135 to 119 mm Hg (P = 0.045) and from 75 to 65 mm Hg (P = 0.015) compared with treatment with subtherapeutic CPAP. In contrast, treatment with therapeutic CPAP did not decrease sympathetic activity as assessed from muscle sympathetic nerve activity. CONCLUSIONS: Decrease in BP by treatment with CPAP in patients with DM, CKD, and OSA indicates the contribution of OSA to severity of HTN in this clinical scenario. Decrease in BP in the absence of changes in sympathetic activity is suggestive that other mechanisms induced by OSA play a larger role in the maintenance of HTN in these patients.

CONTEXTE: Les patients atteints d'apnée obstructive du sommeil (AOS) présentent une activité sympathique accrue qui est souvent accompagnée d'hypertension artérielle (HTA) réfractaire. Le traitement de l'AOS par ventilation en pression positive continue (CPAP, pour Continuous Positive Airway Pressure) diminue la pression artérielle (PA) à l'état de veille et durant le sommeil ainsi que l'activité sympathique. Cette étude était conçue pour évaluer l'effet du traitement de l'AOS par CPAP sur l'activité sympathique et la PA chez des patients atteints de diabète sucré (DS), d'insuffisance rénale chronique (IRC) et d'HTA réfractaire. MÉTHODOLOGIE: Il s'agissait d'une étude à double insu et à répartition aléatoire contrôlée par simulation. Les patients atteints de DS, d'IRC et d'HTA réfractaire ont été répartis de façon aléatoire pour recevoir un traitement par CPAP thérapeutique ou subthérapeutique pendant 6 semaines. Une surveillance ambulatoire de la PA et une évaluation de l'activité nerveuse sympathique musculaire sur 24 h ont été effectuées chez les patients avant et après 6 semaines de traitement. RÉSULTATS: Comparativement à la CPAP subthérapeutique, la CPAP thérapeutique a entraîné une diminution significative de la PA systolique et de la PA diastolique à l'état de veille, qui sont passées respectivement de 144 à 136 mmHg (p = 0,004) et de 79 à 74 mmHg (p = 0,004). La même observation a été faite à l'égard de la PA systolique et de la PA diastolique durant le sommeil, qui sont passées respectivement de 135 à 119 mmHg (p = 0,045) et de 75 à 65 mmHg (p = 0,015). En revanche, l'évaluation de l'activité nerveuse sympathique musculaire n'a révélé aucune diminution de l'activité sympathique associée au traitement par CPAP thérapeutique. CONCLUSIONS: La diminution de la PA associée au traitement par CPAP chez les patients atteints de DS, d'IRC et d'AOS indique que l'AOS contribue à l'intensité de l'HTA dans ce scénario clinique. La diminution de la PA en l'absence de modification de l'activité sympathique laisse supposer que d'autres mécanismes induits par l'AOS jouent un rôle plus important dans le maintien de l'HTA chez ces patients.