Endothelial Dysfunction, Left Ventricular Dysfunction, Left Ventricular Hypertrophy, Vascular Stiffness
Conditions
Brief summary
The proposed mechanistic trial will test the effect of dietary sodium reduction on cardiac and vascular structure and function in those with elevated blood pressure or hypertension. Findings from this study will fill the knowledge gap on the underlying mechanisms of dietary sodium intake on cardiovascular disease risk in addition to blood pressure and could provide further evidence on sodium reduction for the prevention of cardiovascular disease.
Detailed description
High dietary sodium intake increases risk of cardiovascular disease (CVD) independent of established risk factors, including blood pressure (BP). Non-BP mediated mechanisms underlying the increased risk of CVD associated with dietary sodium intake are not well understood, but observational studies suggest direct target organ damage in the heart and vasculature might play an important role. Little evidence exists from randomized controlled trials (RCTs) on target organ effects of dietary sodium reduction, and the National Academy of Medicine has recommended future research to test the effects of different sodium intake levels on endothelial and vascular function in order to to better characterize the relationship between sodium intake and chronic disease. The overall objective of the proposed mechanistic trial is to test the effect of dietary sodium reduction on cardiac and vascular structure and function. Specifically, the proposed trial will test whether dietary sodium reduction (targeting a dietary sodium intake of \<2,300 mg/day) will improve left ventricular mass index (LVMI), left ventricular global longitudinal strain (LVGLS), carotid-femoral pulse wave velocity (cfPWV), and flow-mediated dilation (FMD) compared to usual intake. Additionally, we will test whether this effect is independent from BP reduction. We will recruit 256 people with elevated BP or hypertension from the greater New Orleans area and randomly assign them to a dietitian-led behavioral intervention aimed at decreasing dietary sodium intake to \<2,300 mg/day for 12 months or to a usual diet. Study outcomes, including cardiac magnetic resonance imaging (CMR)-determined LVMI and LVGLS, cfPWV, and FMD, will be measured at baseline, 6-month, and 12-month clinic visits using standardized protocols with stringent quality control. These outcomes are validated biomarkers for target organ damage and predict the risk of clinical CVD events. In primary analyses, the effect of sodium reduction on each subclinical CVD endpoint will be compared between the sodium reduction and usual diet groups according to the intention-to-treat principle without adjusting for covariates. In secondary analyses, changes in ambulatory and clinical BP will be adjusted to assess the BP-independent effect of dietary sodium reduction on each subclinical CVD endpoint. The proposed trial has 85% statistical power to detect a clinically significant difference in changes of the four co-primary outcomes (10 g/m2 in LVMI, 1.3% in LVGLS, 0.9 m/s in cfPWV, and 1.1% in FMD) over 12 months between the two groups at a 2-sided significance level of 0.0125 (0.05/4). Findings from this trial will fill the knowledge gap of the underlying mechanisms of dietary sodium intake on CVD risk and provide further evidence on sodium reduction for CVD prevention.
Interventions
BEHAVIORALSodium Reduction Intervention
The sodium reduction intervention is a dietician-led behavioral intervention consisting of two phases, first a 3-month intensive intervention phase, followed by a 9-month maintenance phase. The overall goal of the intervention is to reduce sodium intake to \<2,300 mg per day based on the most recent guideline from the National Academies of Medicine. Both phases will include individual and group behavioral modification counseling designed to facilitate a reduction in dietary sodium intake.
Sponsors
Johns Hopkins University
Tulane University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Outcomes Assessor)
Masking description
Clinical and laboratory staff members who assess the study outcomes will be blinded to participant intervention assignment. Study participants, investigators, and study staff members who conduct the intervention cannot be blinded to intervention assignment because this is a dietary behavioral intervention trial.
Intervention model description
Eligible participants will be randomized 1:1 into the dietitian-led behavioral intervention and usual diet.
Eligibility
Sex/Gender
ALL
Age
40 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Men or women aged ≥40 years. Individuals \<40 years are at a low risk for clinical and subclinical CVD * Elevated BP or hypertension (systolic BP ≥120 mmHg and diastolic BP ≥80 mmHg with or without use of antihypertensive medications)
Exclusion criteria
* Glomerular filtration rate (eGFR) \<30 or end-stage renal disease (kidney transplant or chronic dialysis) * History of cardiovascular disease * Shift worker or regularly work at night * Cancer requiring chemotherapy or radiation treatment in the previous two years * Current pregnancy or breastfeeding or plans to become pregnant during the study * Consumption of ≥21 alcoholic drinks/week * Current participation in another lifestyle intervention or drug trial * Current residence or planned residence that makes it difficult to meet trial requirements * Other concerns regarding ability to meet trial requirements (at the discretion of the study coordinator)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Left Ventricular Global Longitudinal Strain (LVGLS) from baseline to 12 months | 12 months | Cardiac magnetic resonance imaging will be used to determine LVGLS. |
| Change in Left Ventricular Mass Index (LVMI) from baseline to 12 months | 12 months | Cardiac magnetic resonance imaging will be used to determine left ventricular mass (LVM). LVM will be indexed to body surface area. |
| Change in Pulse Wave Velocity (PWV) from baseline to 12 months | 12 months | A carotid tonometer will be used to measure carotid-femoral PWV. |
| Change in Flow-Mediated Dilation (FMD) from baseline to 12 months | 12 months | Endothelial-dependent FMD will be quantified using high resolution ultrasound. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Left Ventricular Volumes | Baseline, 6 months, and 12 months | Cardiac magnetic resonance imaging will be used to determine left ventricular volumes. |
| Aortic Pulse Wave Velocity | Baseline, 6 months, and 12 months | Cardiac magnetic resonance imaging will be used to determine aortic pulse wave velocity. |
| Left Atrial Maximum and Minimum Volume | Baseline, 6 months, and 12 months | Cardiac magnetic resonance imaging will be used to determine left atrial maximum and minimum volumes. |
| Left Atrial Ejection Fraction | Baseline, 6 months, and 12 months | Cardiac magnetic resonance imaging will be used to determine left atrial ejection fraction. |
| Left Atrial Global Strain | Baseline, 6 months, and 12 months | Cardiac magnetic resonance imaging will be used to determine left atrial global strain. |
Countries
United States
Contacts
Primary ContactMarigny Bostock, MA, CHES
Outcome results
None listed