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Mechanisms of Refractory Hypertension (High and Low Salt Diet)

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ClinicalTrials.gov Identifier: NCT02357017
Recruitment Status : Recruiting
First Posted : February 6, 2015
Last Update Posted : September 5, 2017
Sponsor:
Information provided by (Responsible Party):
David Calhoun, University of Alabama at Birmingham

Brief Summary:
The purpose of the study is to test the hypothesis that persistent fluid retention and high sympathetic output contributes to the development of refractory hypertension (HTN). The investigators will determine, in a cross-over assessment of high and low salt diets, if dietary sodium restriction reduces 24-hr ambulatory BP in patients with refractory HTN. Moreover, the investigators will determine if dietary sodium restriction lessens the severity of obstructive sleep apnea (OSA) in patients with refractory HTN.

Condition or disease Intervention/treatment Phase
Hypertension Dietary Supplement: NaCl tablets Not Applicable

Detailed Description:

We are proposing a unique phenotype of antihypertensive treatment failure that we refer to as refractory HTN. We have come to feel that while resistant (RHTN) represents a broad phenotype with multiple and overlapping etiologies of treatment resistance, there is a unique subset of patients who never achieve BP control in spite of maximal therapy. In a recently published retrospective analysis of our clinic experience, we found that patients with refractory HTN comprised about 10% of patients referred to us for RHTN.

A large number of intervention studies have verified the benefit of dietary salt restriction to reduce BP. We made such an assessment in a prospective, randomized, cross-over comparison of high- and low salt diets in 12 patients with confirmed RHTN. The average reduction in BP going from high to the low salt diet was 23/10 mmHg in the clinic and 20/10 mmHg during 24-hr ambulatory BP monitoring. These dramatic results demonstrated that patients with RHTN are exquisitely salt-sensitive and highlight the degree of BP reduction that can be accomplished with meaningful salt restriction. However, we are proposing the novel hypothesis that refractory HTN is mechanistically unique from RHTN in that it is not secondary to recalcitrant fluid retention.

Determining an association between dietary salt restriction and severity of obstructive sleep apnea (OSA) would potentially help us to find new therapies guided towards achieving better control of BP in patients with refractory HTN. We will investigate the effect of dietary salt intake on severity of OSA vascular function in patients with refractory HTN by doing vascular studies (pulse wave analysis/velocity, calculating thoracic impedance)).


Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 40 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)
Primary Purpose: Prevention
Official Title: Mechanisms of Refractory Hypertension (High and Low Salt Diet)
Study Start Date : February 2015
Estimated Primary Completion Date : January 2019
Estimated Study Completion Date : January 2019

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Sodium

Arm Intervention/treatment
Active Comparator: Low salt diet
The low-salt meals will be formulated to provide 50 mmol of sodium per day. Two diets with different caloric amounts (2000 or 2500) will be available.
Dietary Supplement: NaCl tablets
Active Comparator: High salt diet
High dietary salt intake, NaCl tablets (6 grams/day) will added to the subject's study diet in order to increase dietary sodium intake to >250 mmol/day.
Dietary Supplement: NaCl tablets



Primary Outcome Measures :
  1. Change in 24-hour ambulatory systolic blood pressure (BP). [ Time Frame: baseline to 4 weeks ]
    The mean change in blood pressure for each group after receiving 4 weeks of either a low salt diet compared to High dietary salt intake. The low-salt meals will be formulated to provide 50 mmol of sodium per day. Two diets with different caloric amounts (2000 or 2500) will be available. High dietary salt intake, NaCl tablets (6 grams/day) will added to the subject's study diet in order to increase dietary sodium intake to >250 mmol/day.



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Ages Eligible for Study:   19 Years to 80 Years   (Adult, Older Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   No
Criteria

Inclusion Criteria:

  • Adult subjects ≥ 19 years of age
  • Refractory hypertension defined as office BP > 140/90 that is uncontrolled with at least 5 different classes of antihypertensive medications
  • Self-reported adherence >80% with prescribed antihypertensive medications

Exclusion Criteria:

  • Severe hypertension (office BP >160/100 mm Hg)
  • History of congestive heart failure (ejection fraction of <40%)
  • Chronic kidney disease (creatinine clearance <60 ml/min)
  • History of cardiovascular disease (stroke, TIA, myocardial infarction, or revascularization procedure)
  • White coat hypertension defined as office BP >140/90 mm Hg and ambulatory daytime BP <135/85 mm Hg
  • Pregnant or nursing women

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02357017


Contacts
Contact: Felice Cook 205-934-1400 fycook@uab.edu

Locations
United States, Alabama
David A. Calhoun, MD Recruiting
Birmingham, Alabama, United States, 35214
Contact: David A. Calhoun, MD    205-934-4633    dcalhoun@uab.edu   
Sponsors and Collaborators
University of Alabama at Birmingham
Investigators
Principal Investigator: David A. Calhoun, MD Cardiology Department - University of Alabama at Birmingham

Responsible Party: David Calhoun, Principal Investigator, University of Alabama at Birmingham
ClinicalTrials.gov Identifier: NCT02357017     History of Changes
Other Study ID Numbers: B000502641
First Posted: February 6, 2015    Key Record Dates
Last Update Posted: September 5, 2017
Last Verified: August 2017

Additional relevant MeSH terms:
Hypertension
Vascular Diseases
Cardiovascular Diseases