A Prospective Randomized Unblinded Study of Ketogenetic Versus Mixed Diet on Exercise Tolerance in Subjects With the Metabolic Phenotype of Heart Failure With Preserved Ejection Fraction

Brief Summary

Detailed Description

Participants will be randomized to either a ketogenic diet (KD), or a low-fat diet (MD). Participants will eat the specified diet for a period of 6-months and be supported by dietary coaching. All foods and/or groceries will be provided at no cost for the first six weeks of the study. After the initial 6 weeks, and for the next 20-22 weeks, participants will change into a free-living diet period where food will not be supplied but they will receive educational materials and frequent coaching from a dietitian to help maintain the specified diet. Both diets are based on a slight reduction in dietary caloric requirements, so some weight loss should occur over the 6-month intervention. Ketone and glucose values will be monitored over a 2-week period at baseline, during the conclusion of the first 6 weeks, as well as the final 2-week period at the end of the 6-month study. Participants will apply a sensor one week prior to starting the study to capture one week of baseline metabolic status and the first week of the diet. Another sensor will be applied for week 5 to week 7, and a third sensor for weeks 25 to 26 at the end of the diet. Weight, blood pressure, oxygen saturation, resting heart rate, and activity level will also be monitored. Throughout the duration of the study, participants will be monitored closely, and diabetes and diuretics medications adjusted by physicians involved in this study. Other medications will be continued and guided by your regular physicians. Both groups will be supported from the research physicians on a weekly basis (including medication changes). The duration of the study is expected to last for approximately 6-month. All participants will undergo the following tests on 2 separate visit days at these 3 testing time points during the study (baseline, 6 weeks, and end of the study (26 weeks) unless specified. These tests include: 1. An in-person physical exam by one of the physician investigators. 2. A Dual-energy X-ray absorptiometry (DXA) test, which is a test to measure your body composition. There is a small amount of radiation used in DXA, which is extremely low (by comparison, a standard chest x-ray is 125 times more radiation than a DXA scan). 3. Two cardiac magnetic resonance imaging (MRI) scans. One consisting of non-contrast resting scans including elastography (MR safe drum-like device will generate mechanical waves on specific organs to test the stiffness of these organs) and another consisting of a contrast-enhanced MRI scan of the heart (The one with contrast will only be performed twice for the study, once at the baseline and once end of the study). 4. A six-minute walk test (6MWT). You will walk along an even, undisturbed corridor for 6 minutes. A qualified person will supervise your test. The test has been used as a measure of exercise capacity in many patient populations and is extremely safe. 5. A cardiopulmonary stress test (CPET), also know as an oxygen consumption test (VO2). During the CPET you will be asked to exercise on a treadmill or using an ergometer while breathing into a mask. This will be performed on a separate day from the 6MWT. 6. Up to four tablespoons of blood will be drawn for a number of tests. Blood draws may cause discomfort at the skin puncture site and a small bruise may develop that may persist for several weeks. There is also a small possibility of an infection. These risks are identical to standard clinical blood draws. 7. A 24-hour urine collection.

Primary Outcomes

Secondary Outcomes

• Change in New York Heart Association (NYHA) class(baseline, 6 weeks, and end of the study (26 weeks))
• Change in Quality of Life Questionnaire(baseline, 6 weeks, and end of the study (26 weeks))
• Change in Cardiac Output (L/min) via cardiovascular magnetic resonance imaging (CMR) .(baseline, 6 weeks, and end of the study (26 weeks))
• Change Stroke Volume(mL) via cardiovascular magnetic resonance imaging (CMR)(baseline, 6 weeks, and end of the study (26 weeks))
• Percent change in ejection fraction via cardiovascular magnetic resonance imaging (CMR)(baseline, 6 weeks, and end of the study (26 weeks))
• Metabolic Panel(baseline, 6 weeks, and end of the study (26 weeks))
• Lipid Panel(baseline, 6 weeks, and end of the study (26 weeks))
• B-natriuretic peptide (BNP)(baseline, 6 weeks, and end of the study (26 weeks))
• Continuous glucose/ketone monitor (CGM/CKM)(Up to ~ 26 weeks)