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.

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.

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.

Non-Adherence is Common in Patients with Apparent Resistant Hypertension: a Systematic Review and Meta-Analysis

BACKGROUND

The prevalence of medication non-adherence in the setting of resistant hypertension varies from 5 to 80% in the published literature. The aim of this systematic review was to establish the overall prevalence of non-adherence and evaluate the effect of the method of assessment on this estimate.

METHODS

MEDLINE, EMBASE, Cochrane, CINAHL, and Web of Science (database inception to Nov 2020) were searched for relevant articles. We included studies including adults with a diagnosis of resistant hypertension, with some measure of adherence. Details about the method of adherence assessment were independently extracted by two 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 non-adherence and the prevalence using direct and indirect methods of assessment.

RESULTS

42 studies comprising 71353 patients were included. The pooled prevalence of non-adherence was 37% (95% confidence interval 27 to 47 %) and lower for indirect methods (20%, 95% CI 11 to 35 %), than for direct methods (46%, 95% CI 40 to 52 %). Metaregression suggested study level 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 non-adherence, and report less than half the rates as direct methods (direct observed therapy or urine assays). The overall prevalence of non-adherence in apparent treatment resistant hypertension is extremely high, and necessitates a thorough evaluation of non-adherence in this setting.

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 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. We showed that 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-determine peak oxygen uptake) semi-recumbent cycling in the heat (35°C, 20% relative humidity). Cutaneous vascular conductance and sweat rate were assessed at four forearm skin sites continuously perfused with either: 1) lactated Ringer (Control), 2) 10 mM antioxidant ascorbate, 3) 10 mM 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 cutaneous vascular conductance or sweating in either group (P = 0.619). However, L-NAME reduced cutaneous vascular conductance 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 (236/250 words) This article is protected by copyright. All rights reserved.

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

OBJECTIVE

1) Examine pooled effects of hypertension on nitric oxide (NO)-dependent vasodilation during local heating across multiple non-glabrous skin regions, and 2) explore regional differences.

METHODS

Responses were compared between fourteen participants with uncomplicated hypertension controlled with medication (7 females, 61±6 years) and fourteen age-matched non-hypertensive controls (6 females; 60±5 years). Cutaneous vascular conductance, normalized to maximum vasodilation (%CVC_max) 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 33-42°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 N(G)-Nitro-L-arginine methyl ester (L-NAME; ~40min) 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%CVC_max for between-group differences.

RESULTS

Pooled (all-regions) %CVC_max responses were equivalent for baseline (two one-sided t-test; 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).

CONCLUSION

Local heat-induced cutaneous vasodilation was statistically equivalent between individuals with uncomplicated, controlled hypertension and non-hypertensive 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.govNCT03809884. Registered on January 18, 2019

Abstract P128: Direct Observed Therapy In Suspected Resistant Hypertension Is Safe

Introduction: Direct observed therapy (DOT) has emerged as a method for assessment of adherence, particularly in patients with apparent treatment-resistant hypertension (ATRH), in clinical care as well as research. We have previously demonstrated that direct observed therapy resulted in controlled hypertension in 30% of patients with ATRH. In this study we report on the safety of DOT in terms of change in blood pressure (BP) and hypotensive symptoms.

Methods: Patients with ATRH were enrolled in a prospective study of DOT, which was followed by ambulatory blood pressure monitoring on the same day and at one month. DOT was performed by administering all prescribed BP lowering drugs, supervised by a nurse in an outpatient clinic setting. BP and vitals were measured at baseline and every 30 minutes until BP plateau based on two consecutive BP readings. All BP measurements during DOT were performed using an automated oscillometric BP device. In this study, we report the change in BP during DOT, with incidence of orthostatic symptoms, and decrease in systolic BP > 20 mm Hg as outcomes of interest.

Results: 50 patients underwent DOT, 32 men, mean age 62 years on median 4 BP lowering drugs (range 3 to 7). The mean baseline BP was 146/77 mm Hg , and the lowest BP during DOT was 129/68 mm Hg. The median decrease in systolic BP was 14 mm Hg (range 0 to 60) and diastolic BP was 8 mm Hg (range 0 to 37). 5 patients (10%) developed orthostatic symptoms during DOT, none of which required any interventions, and resolved with continued observation. A decrease of > 20 mm Hg in systolic BP was seen in 19 patients (38%), and a systolic BP of < 110 mm Hg was seen in only 6 patients (12%).

Conclusions: DOT caused decrease in BP by >20 mmHg in about 40% of patients. While these large acute decreases in BP were largely asymptomatic, close observation of BP is required until peak BP lowering effect wanes. As decrease in BP is driven by the degree of non-adherence and number of prescribed BP lowering drugs, our safety record has limitation dictated by the number of subjects enrolled, and relatively small number of patients with more than 5 BP lowering drugs.

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.

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.

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.

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 impact 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, non-heat acclimatized young (18-30 y, n=13) and older (50-70 y) men (n=14), and non-heat acclimatized older men with T2D (n=10) or HTN (n=13) during moderate-intensity (metabolic rate: 200 W/m2) walking for 180 min (or until termination) in environments above (28 and 32°C WBGT) and below (16 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 (109 [91, 173] min; p=0.010) compared to 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.

Inter-arm difference in blood pressure in patients referred to tertiary hypertension center: Prevalence, risk factors, and relevance to physicians

The prevalence of inter-arm BP difference is high in hypertension and is associated with adverse cardiovascular outcomes. We performed a retrospective chart review of prevalent patients in the Ottawa Hospital Hypertension Center to assess for prevalence, risk factors, and whether finding of inter-arm BP difference >10 mmHg leads to investigations of the aorta and aortic arch. Inter-arm BP difference among 493 patients was present in 16.2% (95% confidence interval [CI]13.3-19.9%), and it was associated with presence of peripheral arterial disease. Physicians did not investigate ascending aorta and aortic arch for causes of the clinically significant inter-arm BP difference.

Renal infarct in a COVID-19-positive kidney-pancreas transplant recipient

The novel coronavirus disease 2019 (COVID-19) is associated with increased risk of thromboembolic events, but the extent and duration of this hypercoagulable state remain unknown. We describe the first case report of renal allograft infarction in a 46-year-old kidney-pancreas transplant recipient with no prior history of thromboembolism, who presented 26 days after diagnosis of COVID-19. At the time of renal infarct, he was COVID-19 symptom free and repeat test for SARS-CoV-2 was negative. This case report suggests that a hypercoagulable state may persist even after resolution of COVID-19. Further studies are required to determine thromboprophylaxis indications and duration in solid organ transplant recipients with COVID-19.

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.

Unintended Consequences: Perils of Renal Revascularization for Severe Hypertension

Revascularization of atherosclerotic renal artery stenosis may cure hypertension, but paradoxically, improvement in systemic blood pressure in response to successful revascularization may precipitate ischemia in other organs affected by previously silent atherosclerotic disease. We describe bowel ischemia secondary to preexisting celiac artery stenosis after revascularisation. Prior knowledge of multivessel disease facilitated prompt diagnosis and management of this condition.

The Prevalence of Nonadherence in Patients With Resistant Hypertension: A Systematic Review Protocol

Background

Resistant hypertension, usually defined as blood pressure remaining above goal despite the concurrent use of 3 or more antihypertensive agents of different classes, is common (about 10% prevalence) and known to be a risk factor for cardiovascular events. These patients also undergo more screening intensity for secondary hypertension. However, not all patients with apparent treatment-resistant hypertension have true resistant hypertension, with some of them being nonadherent to prescribed pharmacotherapy. The prevalence of nonadherence varies from about 5% to 80% in the published literature. However, the relative contributions of intentional and nonintentional nonadherence are not well described. Nonintentional nonadherence refers to occasional forgetfulness and/or carelessness and can sometimes be related to an inability to follow instructions, because of either cognitive or physical limitations. Intentional nonadherence refers to an active process in which a patient may choose to alter the prescribed medication regimen by discontinuing medications, skipping doses, or modifying doses or dosing intervals.

Objective

Our objective is to establish the overall prevalence of nonadherence in the apparent treatment-resistant hypertension population and evaluate the relative contributions of nonintentional and intentional nonadherence subtypes.

Design

We will conduct a systematic review and meta-analysis.

Setting

We will include observational studies and randomized controlled trials where adherence to antihypertensive medications is measured using a test of adherence, either direct or indirect.

Patients

We will include adult human participants aged 18 years or older with a diagnosis of resistant hypertension.

Measurements

Data extracted from individual studies will include title, first author, design, country, publication year, funding body, method of assessing adherence to antihypertensive medication, prevalence of medication nonadherence, definition of resistant hypertension, sample size, sex, mean age, and coexistent comorbidities.

Methods

A librarian will search the databases Medline, EMBASE, Cochrane, CINAHL, and Web of Science for studies meeting criteria for inclusion. Two reviewers will independently screen the titles and abstracts retrieved and assess the methodological quality of eligible full-text articles using the Cochrane Risk of Bias tool for clinical trials and the Newcastle-Ottawa Scale for observational studies. Summary estimates of prevalence will be generated using pooled analysis using the random-effects method. Subgroup analyses, sensitivity analyses, and evaluation of publication bias will also be performed.

Results

The outcomes of interest are the pooled prevalence of nonadherence to antihypertensive medication in apparent treatment-resistant hypertension and the prevalence of nonadherence based on different methods of assessing nonadherence (indirect vs direct), which will allow us to estimate the relative proportion of unintentional and intentional nonadherence subtypes in the overall phenomenon of medication nonadherence.

Limitations

Possible limitations of this study include the finding of severe heterogeneity, the limitations of the literature search, publication bias, and the lack of granular data in the published studies for a study-level meta-analysis.

Conclusions

This systematic review will provide a synthesis of current evidence on the prevalence of medication nonadherence in apparent treatment-resistant hypertension and on the relative contributions of nonintentional and intentional nonadherence subtypes. These findings will provide clinicians with a better understanding of the factors underlying treatment-resistant hypertension and will serve as a strong research base to guide future research on interventions to address medication nonadherence as well as the nonintentional and intentional subtypes.

Trial registration

This protocol has been registered with PROSPERO. We will add registration details once available.

Use of Directly Observed Therapy to Assess Treatment Adherence in Patients With Apparent Treatment-Resistant Hypertension

This cohort study evaluates the association of directly observed therapy with treatment adherencee in patients with apparent treatment-resistant hypertension.

Alpha-Blocker Use and the Risk of Hypotension and Hypotension-Related Clinical Events in Women of Advanced Age

Alpha-blockers (ABs) are commonly prescribed as part of a multidrug regimen in the management of hypertension. We set out to assess the risk of hypotension and related adverse events with AB use compared with other blood pressure (BP) lowering drugs using a population-based, retrospective cohort study of women (≥66 years) between 1995 and 2015 in Ontario, Canada. Cox proportional hazards examined the association of AB use and hypotension and related events (syncope, fall, and fracture) compared with other BP lowering drugs matched via a high dimensional propensity score. The primary outcome was a composite of hospitalizations for hypotension and related events (syncope, fractures, and falls) within 1 year. From 734 907 eligible women, 14 106 were dispensed an AB (mean age, 75.7; standard deviation 6.9 years, median follow-up 1 year) and matched to 14 106 dispensed other BP lowering agents. The crude incidence rate of hypotension and related events was 95.7 (95% CI [confidence interval], 90.4–101.1, events 1214 [8.6%]) with AB and 79.8 (95% CI, 74.9–84.7 per 1000 person-years, events 1025 [7.3%]) with other BP lowering medications (incident rate ratio, 1.20; 95% CI, 1.10–1.30). The risk was higher for hypotension (hazard ratio, 1.71; 95% CI, 1.33–2.20) and syncope (hazard ratio, 1.44; 95% CI, 1.18–1.75) with no difference in falls, fractures, adverse cardiac events, or all-cause mortality. Treatment of hypertension in women with ABs is associated with a higher risk of hypotension and hypotension-related events compared with other BP lowering agents. Our findings suggest that ABs should be used with caution, even as add on therapy for hypertension.

Effect of hemodialysis on extracellular vesicles and circulating submicron particles

Background

Although hemodialysis is a highly effective treatment for diffusive clearance of low molecular weight uremic toxins, its effect on circulating extracellular vesicles and submicron particles is less clear. The purpose of this study was to examine the impact of hemodialysis on circulating levels of submicron particles.

Methods

Plasma samples from patients were collected immediately before and after the mid-week hemodialysis session. Total submicron particles were assessed by nanoparticle tracking analysis and levels of endothelial (CD144⁺), platelet (CD41⁺), leukocyte (CD45⁺), and total (Annexin V⁺) membrane microparticles (MPs) were assessed by flow cytometry.

Results

Total submicron particle number was significantly lower post-dialysis with reductions in particles < 40 nm, 40–100 nm, and 100–1000 nm in size. Circulating annexin V⁺ MPs, platelet MPs, leukocyte MPs, and endothelial MPs were all reduced following dialysis. Assessment of protein markers suggested that extracellular vesicles were not present in the dialysate, but rather adsorbed to the dialysis membrane.

Conclusions

In summary, hemodialysis is associated with reductions in circulating submicron particles including membrane MPs. Accordingly, there may be significant interdialytic variation in circulating submicron particles. Investigators interested in measuring extracellular vesicles in patients undergoing hemodialysis should therefore carefully consider the timing of biosampling.

Abstract P375: Association Between Use of Alpha-Blockers and Hypotension and Hypotension-Related Clinical Events in Patients With Hypertension

Importance: Alpha- blockers (AB) are commonly prescribed agents in the treatment of hypertension. Little is known regarding the risk of hypotension and hypotension-related clinical outcomes in patients with advanced age with ongoing treatment for hypertension.

Objective: To assess the risk of hypotension and hypotension-related adverse events (syncope, falls, fractures), major adverse cardiac events and all-cause mortality with AB use compared to other anti-hypertensives.

Methods: Population-based, retrospective cohort study of 933,033 eligible adults of advanced age (> 66 years) prescribed an anti-hypertensive medication between 1995 and 2015 in Ontario, Canada. A high dimensional propensity score was used to match AB prescription to other anti-hypertensives. AB exposure was modeled as a time-varying and cumulative covariate using extended, conditional Cox proportional hazards to examine the association with outcomes. Primary outcome was hospitalization or emergency room usage for hypotension and related complications (syncope, fractures, falls). Secondary outcomes included major adverse cardiovascular events and all-cause mortality.

Results: Among 69,092 matched patients prescribed AB, the incident rate of hypotension related complications were higher compared to other anti-hypertensives (hypotension 1.15 vs. 0.39, syncope 1.47 vs. 0.46, falls 4.37 vs. 1.37, fractures 2.23 vs. 0.69 per 100 person-years of follow-up). In time-varying exposure models with additional adjustment for the total number of anti-hypertensives, the higher risk persisted (hypotension HR 1.34 95%CI 1.26-1.43, syncope HR 1.49 95%CI 1.41-1.57, falls HR 1.27 95%CI 1.23-1.32, HR fractures 1.41 95%CI 1.34-1.48). Secondary outcomes of MACE and all-cause mortality were higher or similar among AB users (MACE IR 7.03 vs. 2.31, mortality 6.54 vs 6.37 per 100 person-years follow-up). The risk was highest among those > 85 and differed by the number of total anti-hypertensives prescribed.

Conclusions: The use of AB is associated with a higher risk of hypotension-related events and other complications. Our findings suggest other anti-hypertensive agents be considered especially among those of advanced age or based on the number of total anti-hypertensive agents.

Abstract P227: The Feasibility of Interventions to Increase Potassium Intake for Hypertension: A Systematic Review of the Evidence

Background: Increased potassium (K) intake has been reported to decrease blood pressure (BP) in animal studies as well as clinical trials. On this basis, major organizations including the American Heart Association recommend increasing K intake, preferably by diet, as a non pharmacological mean of reducing BP. However, it is not clear if the interventions for efficaciously increasing K intake are reproducible or feasible for translation into public health. Hence, we conducted a systematic review of the evidence to review this from randomized controlled trials (RCTs).

Methods: We conducted a literature search using an information specialist of MEDLINE, EMBASE and Cochrane CENTRAL till November 2017. Two reviewers selected RCTs that were in adults, with an intervention aimed at increasing K intake, with blood pressure as an outcome. From RCTs which reported both a significant change in BP and K using 24 hour urine K, we evaluated the interventions for ease of reproducibility and feasibility based on prespecified criteria.

Results: The initial search retrieved 1199 non-duplicate citations. After applying eligibility criteria, 90 studies were selected for inclusion. In 31 studies, the change in BP or K was not significant. Of the remaining 59 studies which reported a significant change in K and BP, 47 reported a change in K based on 24 hour urinary K measurement. 32/47 studies used a K supplement, with details provided on dose and administration to make it both reproducible and feasible. 15/47 studies used a dietary intervention, of which in 4, the intervention was not described in sufficient detail to be reproducible.The remaining 11 studies were feeding trials, with intervention consisting of provision of prepared meals, or of food items on a daily basis to make them unfeasible for routine clinical practice.

Conclusions: Dietary potassium interventions from trials in which there was a significant change in K based on 24 hour urine and a significant change in BP are not reproducible or feasible.

Abstract 074: Non-Adherence to Prescribed Blood Pressure Lowering Drugs in Patients With Suspected “Resistant” Hypertension: A Call for Rigorous Adherence Testing

Background: Pseudoresistance from non-adherence to blood pressure (BP) lowering drugs can cause unnecessary medical visits and invasive diagnostic tests and procedures. It also leaves patients at a high risk for vascular outcomes. There is currently no unified approach to the diagnosis of non-adherence. Direct questioning by medical personnel and review of pharmacy filling do not reveal the full extent of non-adherence. Direct observational therapy (DOT), a test where a patient’s BP response is monitored after supervised administration of BP lowering drugs, has never been prospectively evaluated for diagnosis of suspected resistant hypertension (HTN).

Methods: We conducted a prospective study to estimate the prevalence of pseudoresistant HTN using the DOT test. Eligible patients were adults with suspected resistant HTN, defined as daytime average systolic blood pressure (SBP) >135 mmHg on 24-hour ambulatory blood pressure monitoring (ABPM) while on 3 or more BP lowering drugs. Patients confirmed adherence at the clinic, and they had their pharmacy records reviewed. For the DOT, prescribed BP lowering drugs were administered by a nurse at the HTN clinic. BP response was monitored at the office until peak BP effect was reached followed by immediate 24-hour BP ambulatory monitoring, which was repeated at 1 month.

Results: 60 patients were enrolled, and 50 patients completed this study. 30 patients had confirmed resistant HTN. 20 patients had a large SBP decrease during observation immediately post drug administration ( ≥ 20 mmHg) as well as daytime average SBP on 24-hour ABPM (>10 mmHg) as compared to their baseline SBPs. Of these 20 patients, 15 continued to have controlled BP at the 24-hour ABPM done at 1 month post DOT, indicating medium term change in in adherence.

Conclusions: A large proportion of patients with suspected resistant HTN have pseudoresistant HTN from non-adherence. The diagnosis of pseudoresistance was associated with subsequent cure of resistant HTN in 75% of cases. Proper assessment of adherence is essential to avoid unnecessary drug escalation, and/or investigations for secondary HTN. The DOT represents a simple test for diagnosis and management of suspected resistant HTN, with important ramifications for health care policy makers.

Abstract P206: Interarm Difference in Blood Pressure: Prevalence, Risk Factors, and Relevance for Diagnosis of Disease of the Aorta Among Patients Referred to Specialized Regional Hypertension Center

Background: Initial evaluation of hypertension (HTN) should include assessment of blood pressure (BP) in both arms. The prevalence of high interarm differ ranges from 3% in the general adult population to about 10% in the patients with HTN. However, we lack proper estimates of its prevalence, and existing practice of follow up for these patients in a referred population.

Methods: We performed a retrospective chart review of all prevalent patients followed at the Hypertension Center at the Ottawa Hospital. BP data from the first visit were used for assessment for interarm BP difference. We considered interarm difference in either systolic or diastolic BP in excess of 10 mmHg for casual BP by mercury sphygmomanometry to be clinically significant.

Results: 493 patients of 580 patients were included in this study based on available data. The prevalence of clinically significant interarm difference in systolic or diastolic BP was 16.2% and was similar among men and women. These patients were more likely to be smokers (current or previous; 53.5% vs 36.8%) with peripheral arterial disease (PAD, 15% vs 8%). None of these patients had undergone further investigations of ascending aorta/aortic arch.

Conclusions: A significant proportion of referred patients have a high interarm difference in systolic or diastolic BP. No clinical investigations were ordered to evaluate for ascending aorta/aortic arch disease reflecting the physicians’ lack of understanding of its clinical relevance. The association with smoking and PAD suggests underlying aortic/large vessel disease as a potential mechanism in some patients.

Thiazide diuretic-caused hyponatremia in the elderly hypertensive: will a bottle of Nepro a day keep hyponatremia and the doctor away? Study protocol for a proof-of-concept feasibility trial

Background

Hypertension is the most common modifiable risk factor for cardiovascular disease, with an increasing prevalence with age, but with easily available medications to control it. Adverse effects of these medications do limit their use, in particular hyponatremia due to thiazide and thiazide-like diuretics. This is more common in the elderly patients due to a combination of inadequate protein intake and impaired urinary dilution capability, made worse by additional thiazide use. Limiting free water intake and increasing protein intake are often not successful resulting in thiazide avoidance. Daily protein supplement is a potential option in this clinical scenario. We describe the protocol for a feasibility study to explore this option.

Methods

This is a single-arm, prospective, open-label proof-of-concept trial, including elderly patients with thiazide diuretic-induced hyponatremia. Forty patients will be enrolled and receive a bottle of a protein supplement daily, providing 120 mmol of solutes and permitting an extra 163 mL free water loss, for 4 weeks. The main outcome measures will be (1) feasibility for enrollment, (2) safety of the intervention, and (3) potential efficacy of the intervention in improving hyponatremia. Secondary outcome measures will include changes in urine osmolality, body weight, and urea measurements.

Discussion

Thiazide diuretic-induced hyponatremia is an important adverse effect, with significant clinical impact, such as delirium and falls, and limits the use of these potent antihypertensive agents. There are little data on the effect or safety of protein supplementation and also on whether a trial of this is feasible. The results of this proof-of-concept feasibility trial will help plan and execute a larger definitive trial to test protein supplementation as an effective strategy in this condition.

Trial registration

The trial is registered with Clinical trials, registration identifier: NCT02614807.

Hypertension Canada's 2018 Guidelines for Diagnosis, Risk Assessment, Prevention, and Treatment of Hypertension in Adults and Children

Hypertension Canada provides annually updated, evidence-based guidelines for the diagnosis, assessment, prevention, and treatment of hypertension in adults and children. This year, the adult and pediatric guidelines are combined in one document. The new 2018 pregnancy-specific hypertension guidelines are published separately. For 2018, 5 new guidelines are introduced, and 1 existing guideline on the blood pressure thresholds and targets in the setting of thrombolysis for acute ischemic stroke is revised. The use of validated wrist devices for the estimation of blood pressure in individuals with large arm circumference is now included. Guidance is provided for the follow-up measurements of blood pressure, with the use of standardized methods and electronic (oscillometric) upper arm devices in individuals with hypertension, and either ambulatory blood pressure monitoring or home blood pressure monitoring in individuals with white coat effect. We specify that all individuals with hypertension should have an assessment of global cardiovascular risk to promote health behaviours that lower blood pressure. Finally, an angiotensin receptor-neprilysin inhibitor combination should be used in place of either an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker in individuals with heart failure (with ejection fraction < 40%) who are symptomatic despite appropriate doses of guideline-directed heart failure therapies. The specific evidence and rationale underlying each of these guidelines are discussed.

Longitudinal Blood Pressure in Late-Stage Chronic Kidney Disease and the Risk of End-Stage Kidney Disease or Mortality (Best Blood Pressure in Chronic Kidney Disease Study)

Whether different methods of quantitating blood pressure (BP) in late chronic kidney disease better mimic pathophysiological processes and clinical outcomes remains unclear. In a retrospective study, we determined the association of BP with end-stage kidney disease (ESKD) and all-cause mortality with BP modeled at baseline versus longitudinally with time-varying Cox models as (1) current (most recent) clinic visit, (2) lag (visit immediately preceding the current), (3) cumulative (average of previous measurements), and (4) change from baseline to the most recent. Among 1203 (6913 visits) study patients, the mean age and baseline estimated glomerular filtration rate were 66 and 18 mL·min −1 ·1.73 m −2 ), and 40% were female. Patients had a mean of 6.7 BP measurements, 540 (44.8%) reached ESKD, and 141 (11.7%) died. For systolic BP >160, current (hazard ratio [HR], 1.67), cumulative (HR, 1.58), and a rise to >160 from baseline 120 to 160 (HR, 1.60) were associated with ESKD. Similarly, diastolic BP >85 was associated with ESKD when modeled as current (HR, 1.47), lag (HR, 1.63), cumulative (HR, 2.15), or change from baseline (rise to >85 from a baseline of 60–85; HR, 1.62). Both low SBP (<120), when modeled as current (HR, 1.59), cumulative exposure (HR, 1.76), persistently <120 (HR, 2.28), and high SBP (>140), when modeled as cumulative exposure, were associated with all-cause mortality. For diastolic BP, only cumulative >85 was significantly associated with mortality (HR, 2.75). Thus, in late-stage chronic kidney disease, persistently high or rises in systolic BP or diastolic BP are associated with risk of ESKD, whereas baseline BP measures did not convey information on risk.

Abstract P361: Prevalence & Predictors of Orthostatic Hypotension at a Tertiary Care Hypertension Clinic With New Diagnostic Thresholds

Background: Orthostatic hypotension (OH), defined as a decrease of blood pressure (BP) of 20/10 mm Hg (systolic/diastolic) on change in posture from supine to standing is seldom assessed in routine practice because of logistical constraints. A recent study reported a sit-to-stand decrease of 15/7 mm Hg as also having good diagnostic yield. We measured the prevalence & risk factors associated with OH with the new threshold of sit-to- stand of either ≥ 15 mm Hg in systolic (SBP) or ≥ 7 mm Hg in diastolic BP (DBP).

Methods: We reviewed medical charts of patients being followed at Renal Hypertension Center, a referral centre for difficult to control hypertension. Sitting BP is measured after 5 minutes of resting, as an average of 5 measurements with an automated device. Standing BP is measured three times at one minute intervals and averaged. OH was determined on the basis of the difference in either average SBP or DBP. Demographic characteristics, comorbidities, medication details, laboratory values and BP measurements were extracted.

Results: Data from 219 patients was extracted (see table). The overall difference in SBP (sitting - standing)was 0.94 and DBP was 2.1 mm Hg. 190 patients (87%) did not have OH, whereas 29 (13%) had OH using either SBP or DBP thresholds. The difference in SBP and DBP was 17 mm and 6 mm Hg in those with OH, versus 1.6 and 3 mm Hg amongst those without OH respectively. Higher SBP was significantly associated with OH; age, gender, diabetes, number and hypertension drug class were not.

Conclusion: Amongst referred patients to a specialist hypertension clinic, the prevalence of OH using a threshold of 15/7 mm Hg was 13%. The new diagnostic threshold allows for easy assessment of OH.

Abstract P431: Renal Artery Stenosis Caused by a Bcr-Abl Tyrosine Kinase Inhibitor: Blood Pressure Response to Revascularization

Introduction: Bcr-Abl tyrosine kinase inhibitors (TKI) are first line agents for management of chronic myelogenous leukemia (CML). Amongst the second generation TKIs, which have less resistance and improved side effect profile, nilotinib and ponatinib have also been reported to be associated with vascular adverse events (VAEs), including systemic and peripheral arterial stenosis. We report on a patient with CML treated with ponatinib, who developed bilateral renal artery stenoses, difficult to control hypertension, and responded to revascularization.

Case: A 55 year old man, with CML due to a Bcr-Abl truncating mutation diagnosed in 2007, was treated with ponatinib 45 mg daily starting in 2011, which induced a complete remission. He subsequently developed hypertension. Hypertension appeared angiotensin II-dependent as BP normalized on combination of candesartan 32 mg once daily and hydrochlorothiazide 25 mg once daily. This treatment was however associated with an increase in serum creatinine from 1.4 to 2.6 mg/dL. Consistent with our clinical suspicion, a computed tomography angiogram revealed bilateral renal artery stenosis. He eventually required bilateral renal artery angioplasty and stenting as the BP could not be controlled without renin-angiotensin system blockers despite using up 5 classes of BP lowering drugs. Furthermore, follow up imaging of renal arteries showed progressive renal artery stenosis bilaterally. He underwent angioplasty and stenting in the left renal artery and angioplasty of both the branches of the right main renal artery, which could not be stented because of the early branching. After 6 months, BP is within target with 8 mg candesartan, amlodipine 10 mg and bisoprolol 2.5 mg daily, and the renal function is stable (creatinine 1.1 mg/dL). Overall, in this case, renal artery angioplasty and stenting stabilized renal function and improved control of hypertension.

Discussion: Second generation TKIs are associated with VAEs, including renal artery stenosis. Renal artery angioplasty and stenting stabilized renal function and improved control of hypertension in this case. Future research should clarify the mechanisms of VAEs with TKIs, natural history, and long term response to revascularization in this setting.

Abstract 019: Effect of CPAP on Blood Pressure and Central Sympathetic Outflow in Diabetic Patients with OSA, Resistant HTN, and CKD

Introduction: Central sympathetic hyperactivity as assessed by muscle sympathetic nerve activity recordings is thought to play a crucial role in the development and maintenance of hypertension (HTN) in patients with obstructive sleep apnea (OSA). Decreases in daytime and nocturnal blood pressure (BP) in response to treatment with continuous positive airway pressure (CPAP) are paralleled by decreases in muscle sympathetic nerve activity (MSNA). Patients with chronic kidney disease (CKD) have high MSNA. Bilateral nephrectomy, but not renal transplantation normalizes MSNA indicating central sympathoexcitatory effects by renal afferents. The objective of this study was to assess to what extent is HTN driven by central sympathetic hyperactivity in patients with diabetic CKD, OSA, and resistant HTN. Thirteen patients (age 62.2±7.4 years) with diabetic CKD, resistant HTN defined as SBP on 24-hr ABPM above 135 mmHg while on 3 or more BP lowering drugs (including diuretic) with OSA, were randomized to therapeutic CPAP or non-therapeutic CPAP for one months. 24-hr ABPM, plasma catecholamines, aldosterone, and renin, and MSNA were assessed before and 1 months after randomization. Our results show (Table) that in contrast to sham CPAP, therapeutic CPAP decreased daytime and nighttime BP. In contrast, neither therapeutic nor sham CPAP caused any changes in MSNA and plasma catecholamines. In conclusion, decreases in BP in response to CPAP in patients with in diabetic CKD, despite maintained high MSNA, indicate other mechanism contributing to HTN in these patients as well as other central sympathoexcitatory pathways activated.

Time-Varying Association of Individual BP Components with eGFR in Late-Stage CKD

BACKGROUND AND OBJECTIVES

The association of individual BP components with changes in eGFR in patients with late-stage CKD is unknown. The objectives of our study were to examine the associations of systolic BP, diastolic BP, and pulse pressure with continuous temporal changes in eGFR and an eGFR decline ≥30% in late-stage CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We performed a retrospective cohort study (2010-2015) of patients with CKD in a multidisciplinary CKD clinic with an eGFR≤30. The associations of repeat measures of BP (systolic BP, diastolic BP, and pulse pressure) with eGFR were examined using general linear mixed models. The associations of BP components and eGFR decline ≥30% were examined with time-varying Cox models.

RESULTS

In total, 1203 patients were followed for a median of 548 days (interquartile range, 292-913), with an average of 6.7 visits and BP measures per patient. Mean baseline systolic BP, diastolic BP, pulse pressure, and eGFR were 139.2 mmHg, 73.2 mmHg, 64.9 mmHg, and 16.8 ml/min, respectively. Systolic BP and diastolic BP measures over time were statistically significantly associated with changes in eGFR (P<0.001), whereas pulse pressure was not. Patients with extremes of systolic BP (<105 or >170) and high diastolic BP (>90) measures were at a higher risk of GFR decline ≥30% (systolic BP <105: hazard ratio, 1.51; 95% confidence interval, 0.98 to 2.34; systolic BP >170: hazard ratio, 1.62; 95% confidence interval, 1.05 to 2.49; referent systolic BP =121-130; diastolic BP =81-90: hazard ratio, 1.40; 95% confidence interval, 0.99 to 1.86; diastolic BP >90: hazard ratio, 1.83; 95% confidence interval, 1.21 to 2.77; referent diastolic BP =61-70). The findings were consistent after multiple sensitivity analyses. Pulse pressure was not significantly associated with risk of eGFR decline.

CONCLUSIONS

In patients referred to a multidisciplinary care clinic with late-stage CKD, only extremes of systolic BP and elevations of diastolic BP were associated with eGFR decline.

Microparticle Formation in Peritoneal Dialysis: A Proof of Concept Study

BACKGROUND

Injury to the mesothelial layer of the peritoneal membrane during peritoneal dialysis (PD) is implicated in loss of ultrafiltration capacity, but there are no validated biomarkers for mesothelial cell injury. Microparticles (MPs) are 0.1 to 1.0 µm membrane vesicles shed from the cell surface following injury and are sensitive markers of tissue damage. Formation of MPs in the peritoneal cavity during PD has not been reported to date.

METHODS

We designed a single-center, proof of concept study to assess whether peritoneal solution exposure induces formation of mesothelial MPs suggestive of PD membrane injury. We examined MP levels in PD effluents by electron microscopy, nanoparticle tracking analysis (NTA), flow cytometry, procoagulant activity, and Western blot.

RESULTS

NTA identified particles in the size range of 30 to 900 nm, with a mean of 240 (SE: 10 nm). MP levels increased in a progressive manner during a 4-hour PD dwell. Electron microscopy confirmed size and morphology of vesicles consistent with characteristics of MPs as well as the presence of mesothelin on the surface. Western blot analysis of the MP fraction also identified the presence of mesothelin after 4 hours, suggesting that MPs found in PD effluents may arise from mesothelial cells.

CONCLUSIONS

Our results suggest that MPs are formed and accumulate in the peritoneal cavity during PD, possibly as a stress response. Assessing levels of MPs in PD effluents may be useful as a biomarker for peritoneal membrane damage.

Hypertension Canada's 2017 Guidelines for Diagnosis, Risk Assessment, Prevention, and Treatment of Hypertension in Adults

Hypertension Canada provides annually updated, evidence-based guidelines for the diagnosis, assessment, prevention, and treatment of hypertension. This year, we introduce 10 new guidelines. Three previous guidelines have been revised and 5 have been removed. Previous age and frailty distinctions have been removed as considerations for when to initiate antihypertensive therapy. In the presence of macrovascular target organ damage, or in those with independent cardiovascular risk factors, antihypertensive therapy should be considered for all individuals with elevated average systolic nonautomated office blood pressure (non-AOBP) readings ≥ 140 mm Hg. For individuals with diastolic hypertension (with or without systolic hypertension), fixed-dose single-pill combinations are now recommended as an initial treatment option. Preference is given to pills containing an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker in combination with either a calcium channel blocker or diuretic. Whenever a diuretic is selected as monotherapy, longer-acting agents are preferred. In patients with established ischemic heart disease, caution should be exercised in lowering diastolic non-AOBP to ≤ 60 mm Hg, especially in the presence of left ventricular hypertrophy. After a hemorrhagic stroke, in the first 24 hours, systolic non-AOBP lowering to < 140 mm Hg is not recommended. Finally, guidance is now provided for screening, initial diagnosis, assessment, and treatment of renovascular hypertension arising from fibromuscular dysplasia. The specific evidence and rationale underlying each of these guidelines are discussed.

Precision Medicine for Hypertension Management in Chronic Kidney Disease: Relevance of SPRINT for Therapeutic Targets in Nondiabetic Renal Disease

In this review we evaluate the literature to determine if lower blood pressure (BP) targets are beneficial for patients with nondiabetic chronic kidney disease (CKD). Modification of Diet in Renal Disease (MDRD), African American Study of Kidney Disease and Hypertension (AASK), and Ramipril Efficacy in Nephropathy-2 (REIN-2), designed to assess the benefit of lower BP on progression of nondiabetic CKD, generally came to the same negative conclusion. They were not designed and powered to assess an effect of lower BP on cardiovascular outcomes. The Systolic Blood Pressure Intervention Trial (SPRINT) was the first trial designed and powered to address this issue, and showed a clear benefit of a lower targeted and achieved BP. SPRINT did not show any renal benefits from lower BP, and it was not designed to assess this outcome, and it enrolled patients with less "renal risk" per se. A distinguishing feature of SPRINT compared with other large trials is that it highlighted the importance of precise BP measurement methods in defining targets in hypertension treatment. Accordingly, we propose that SPRINT is truly a "game-changing" clinical trial that sets the bar for management of hypertension in select patients with nondiabetic CKD. In these patients, systolic BP target depends critically on the BP measurement method: < 140 mm Hg when derived from 3 readings using a mercury sphygmomanometer after 5 minutes of rest, < 130 mm Hg when calculated from at a minimum of 3 readings using an automated oscillometric device, and < 120 mm Hg when taken using an automated oscillometric device after 5 minutes of unattended rest.

How Accurate Are Home Blood Pressure Devices in Use? A Cross-Sectional Study

Background

Out of office blood pressure measurements, using either home monitors or 24 hour ambulatory monitoring, is widely recommended for management of hypertension. Though validation protocols, meant to be used by manufacturers, exist for blood pressure monitors, there is scant data in the literature about the accuracy of home blood pressure monitors in actual clinical practice. We performed a chart review in the blood pressure assessment clinic at a tertiary care centre.

Methods

We assessed the accuracy of home blood pressure monitors used by patients seen in the nephrology clinic in Ottawa between the years 2011 to 2014. We recorded patient demographics and clinical data, including the blood pressure measurements, arm circumference and the manufacturer of the home blood pressure monitor. The average of BP measurements performed with the home blood pressure monitor, were compared to those with the mercury sphygmomanometer. We defined accuracy based on a difference of 5 mm Hg in the blood pressure values between the home monitor and mercury sphygmomanometer readings. The two methods were compared using a Bland-Altman plot and a student’s t-test.

Results

The study included 210 patients. The mean age of the study population was 67 years and 61% was men. The average mid-arm circumference was 32.2 cms. 30% and 32% of the home BP monitors reported a mean systolic and diastolic BP values, respectively, different from the mercury measurements by 5 mm Hg or more. There was no significant difference between the monitors that were accurate versus those that were not when grouped according to the patient characteristics, cuff size or the brand of the home monitor.

Conclusions

An important proportion of home blood pressure monitors used by patients seen in our nephrology clinic were inaccurate. A re-validation of the accuracy and safety of the devices already in use is prudent before relying on these measurements for clinical decisions.

Reproducibility of carotid-femoral pulse wave velocity in end-stage renal disease patients: methodological considerations

Background

In end-stage renal disease (ESRD) patients, increased arterial stiffness detected by carotid-femoral pulse wave velocity (cf-PWV) is associated with fatal cardiovascular events and all-cause mortality. Since cf-PWV is an operator-dependent technique, poor reproducibility may be a source of bias in the estimation of arterial stiffness.

Objectives

We assessed the week-to-week reproducibility of cf-PWV and radial artery pulse wave analysis in healthy subjects and ESRD patients. We also determined the extent of patient eligibility, enrollment, acceptance, and comfort.

Methods

In a cohort study design, independent tonometric examinations of carotid, femoral, and radial arteries were conducted in 20 healthy subjects and 15 ESRD patients attending chronic hemodialysis treatments according to a randomized sequence by two operators on 2 days scheduled 1-week apart. cf-PWV, augmentation index (AIx@HR75) and central pulse pressure (CPP) were the outcome measures. Patients were tested at mid-week and prior to dialysis treatment. The variability on the distance measured between the suprasternal notch and femoral site using two different methods (standard vs direct) was compared. A post-examination survey assessed acceptance and comfort associated with examinations. Reproducibility was evaluated by intra-class correlations (ICCs).

Results

The mean age for healthy subjects and ESRD patients was 45 ± 12 and 63 ± 16 years, respectively. ESRD patients had higher cf-PWV (p = 0.0002), elevated AIx@HR75 (p = 0.003), and increased CPP (p = 0.001) compared to healthy subjects. The mean inter-visit differences for all stiffness indices were non-significant (p > 0.05), but the mean inter-operator differences for the cf-PWV were significant only in the healthy subject group (−0.7 m/s; p = 0.02). The ICCs between operators and visits were higher for the ESRD group compared to the healthy subjects (between operators, 0.870 vs 0.461; between visits, 0.830 vs 0.570). Distances were longer (p < 0.001), but less variable with the standard method compared to the direct method (healthy subjects, p = 0.036; ESRD, p = 0.39). There was a high rate of patient acceptance and minimal discomfort.

Conclusions

Week-to-week measurements of cf-PWV and pulse wave analysis are highly reproducible in ESRD patients prior to hemodialysis treatment. The high reproducibility and minimal test-to-test variations encourage use of cf-PWV to monitor changes in arterial stiffness and the efficacy of interventions in ESRD patients.

Trial registration

ClinicalTrials.gov, NCT02196610.

Electronic supplementary material

The online version of this article (doi:10.1186/s40697-016-0109-6) contains supplementary material, which is available to authorized users.