Effects of the Dietary Approaches to Stop Hypertension(DASH) Sodium-restricted Diet in Diastolic Heart Failure
Effects of the Dietary Approaches to Stop Hypertension(DASH) Sodium-restricted Diet in Diastolic Heart Failure
Heart failure with preserved systolic function (HF-PSF, or 'diastolic heart failure')
 accounts for half of hospitalizations for heart failure in patients over the age of 65. Most
 HF-PSF patients have systemic hypertension (HTN), and characteristic HTN-induced
 cardiovascular changes contribute to HF-PSF. However, it is unclear why most patients with
 HTN never develop HF-PSF or which specific aspects of HTN predispose to HF-PSF.

 In the Dahl S rat, the primary animal model of HF-PSF, high dietary sodium intake suppresses
 the systemic renin-angiotensin-aldosterone system, but upregulates renal and cardiac
 renin-angiotensin-aldosterone system by inducing oxidative stress. In humans, the magnitude
 of blood pressure response to sodium ingestion and depletion can categorize subjects as
 "salt-resistant" and "salt-sensitive." Human salt sensitivity is associated with structural
 and loading conditions that increase the risk for HF-PSF, including HTN, ventricular
 hypertrophy and diastolic dysfunction, arterial stiffening, and increased plasma volume. High
 dietary sodium intake induces oxidative stress in salt-sensitive humans. In humans with HTN
 and normal ventricular systolic function that do not have heart failure, increased oxidative
 stress predicts impaired exercise capacity, ventricular hypertrophy, diastolic dysfunction,
 arterial stiffening, and vascular endothelial dysfunction. The investigators have proposed
 that "salt sensitivity" and the accompanying oxidative stress on the typical high-sodium
 Western diet may contribute to the initiation and progression of HF-PSF.

 In patients with HF-PSF, the investigators will relate dietary changes to biochemical and
 cardiovascular functional measures. The investigators will study subjects on ad-lib diet and
 and following three weeks of rigorous dietary modification with the Dietary Approaches to
 Stop Hypertension (DASH)/sodium-restricted diet (SRD). This diet is richer in natural
 antioxidants and lower in sodium than the usual American diet. The DASH/SRD is recommended to
 lower blood pressure in patients with HTN, and is particularly effective in elderly, obese,
 and salt-sensitive hypertensives. Dietary sodium restriction is recommended for all HF
 patients including those with HF-PSF. The investigators hypothesize that the DASH/SRD will
 have favorable effects on oxidative stress, ventricular and vascular function, and blood
 pressure control in patients with hypertensive HF-PSF.
Inclusion Criteria:

 -  Satisfy European Society of Cardiology guidelines for the diagnosis of HF-PSF (Paulus
 WJ et al. Eur. Heart J. 2007;28:2539-2550).

 -  Framingham criteria for heart failure satisfied

 -  left ventricular ejection fraction ≥ 50% (contrast ventriculography, echocardiography,
 nuclear scintigraphy)

 -  Diastolic dysfunction on previous echocardiogram/catheterization or evidence of
 abnormal neurohormonal activation (B-type natriuretic peptide (BNP) ≥ 100 pg/ml) with
 supporting evidence (atrial fibrillation, left atrial enlargement, left ventricular
 hypertrophy)

 -  History of systemic hypertension

 -  Willing to adhere to provided diet

 Exclusion Criteria:

 -  New York Heart Association Class IV heart failure symptoms

 -  Hospitalization for decompensated heart failure within past one month

 -  Uncontrolled hypertension (seated systolic blood pressure ≥ 180 or diastolic blood
 pressure ≥ 110) at rest, on current antihypertensive regimen

 -  Changes in medical regimen for heart disease or hypertension within past 1 month,
 including diuretic dose adjustment

 -  Primary exercise limitation due to severe pulmonary disease

 -  Poor echocardiographic windows

 -  Worse than moderate mitral or aortic stenosis or insufficiency.

 -  Serum potassium level > 5.0 mmol/L at baseline or prior history of serum potassium
 level > 6.0

 -  Serum calcium/phosphorus product > 50 at baseline

 -  Severe renal insufficiency (current estimated glomerular filtration rate < 30 ml/min)

 -  Severe anemia (hemoglobin < 9 g/dL)

 -  Uncontrolled diabetes mellitus (hemoglobin A1c > 9%)

 -  Non-hypertensive cause of HF-PSF, e.g. amyloidosis, sarcoidosis, constrictive
 pericardial syndromes

 -  Myocardial infarction or unstable angina, including new or worsening anginal syndrome,
 within the past three months

 -  Uncontrolled arrhythmia (including non rate-controlled atrial fibrillation)

 -  Terminal illness expected to result in death within six months or active solid-organ
 cancer

 -  Psychiatric disorder or dementia with potential to compromise dietary adherence