Early Metabolic Adaptations to SGLT2 Inhibition in Heart Failure

Schema Total anticipated enrollment: 40 participants This is an observational study in patients being initiated on an FDA-approved SGLT2i treatment for symptomatic HF (on-label use). This observational study involves supplemental research testing before and after SGLT2i initiation to help define how the treatment affects the body. Study Design This will be a single-center study that will characterize early changes in systemic metabolic and proteomic profiles, skeletal muscle oxidative capacity and six-minute walk distance before and after initiation of SGLT2i treatment. The paired study design will specifically target patients with symptomatic heart failure whose physicians are prescribing FDA-approved SGLT2i treatment. Pre- vs. post-treatment profiling will be performed during the first 4-8 weeks of therapy. Eligibility is not limited to a particular range of LVEF or affected by prior LVEF. Visit Procedures Visit 1: Enrollment/Baseline Visit * Eligibility/Informed Consent * Medical History, Medications Review Visit 2: Pre-SGLT2i Testing * Blood sample collection * Six-minute walk test * Calf MRI with plantar flexion exercise Visit 3: Post-SGLT2i Testing * Blood sample collection * Six-minute walk test * Calf MRI with plantar flexion exercise Study Objectives Primary \- Assess the impact of SGLT2i on systemic metabolomic and proteomic profiles Secondary * Assess the impact of SGLT21 on ambulation * Assess the impact of SGLT2i on skeletal muscle oxidative phosphorylation capacity (SkM OxPhos) * Assess the impact of SGLT2i on skeletal muscle perfusion during exercise Study Endpoints * We will measure changes in venous concentrations of metabolic substrates and intermediates, along with circulating proteomic regulators using both targeted and untargeted surveys. * Differences in distance traveled during a standardized 6 minute walk test. * OxPhos as assessed using CrCEST MRI spectroscopy * MRI-based assessment of SkM Perfusion: Differences in conduit artery blood flow and intramuscular perfusion using vPIVOT MRI imaging Risks and Benefits Overview As an observational study, the risks of this research are confined to those associated with the supplemental testing that is being performed: blood sampling, six-minute walk testing and MRI scanning with foot flexion exercise. Blood sampling and six-minute walk testing have minimal risk. After eliminating individuals with absolute contraindications to MRI scanning, such as retained metal fragments or implanted devices that are not MRI compatible, risks related to this MRI study are limited and include feeling uncomfortable in the MRI scanner and developing minor leg discomfort from the one-foot exercise required. Individuals with implanted pacemakers or defibrillators designated as "MRI-conditional" may be included. Subjects who are not eligible for MRI studies may still participate in the blood sampling and six-minute walk test assessments