Leg Heat Therapy in Heart Failure With Preserved Ejection Fraction

The objective of this pilot study is to establish evidence to support the validity of HT in improving skeletal muscle function and physical capacity of patients with HFpEF. Our central hypothesis is that HT treatment will lead to improvements in skeletal muscle and microvascular function compared to a control intervention. As a result, we anticipate that patients treated with HT will demonstrate improved skeletal muscle microvascular blood flow and oxygenation resulting in enhanced exercise tolerance. To explore this hypothesis, we propose the following specific aim: Explore the effects of home-based HT on exercise tolerance in patients with HFpEF.

Inclusion Criteria: * Men and women older than 18 years * Established diagnosis of heart failure with preserved ejection fraction (HFpEF) including left ventricular ejection fraction (LVEF) ≥50% as evidenced by Doppler echocardiography and/or ratio of the early mitral inflow velocity (E) to septal tissue Doppler velocity (e') \>8 and at least 1 other sign of chronically elevated filling pressures, including an enlarged left atrium (left atrial volume index \>34 mL/m2), an elevated N-terminal pro-brain natriuretic peptide (NT-pro-BNP) level within the past year, long-term loop diuretic use for control of symptoms, or elevated filling pressures (mean pulmonary capillary wedge pressure \>12 mmHg) on prior cardiac catheterization * Stable medical treatment Exclusion Criteria: * Recent hospitalization (within the previous 1 month) * Unstable angina and/or uncontrolled cardiac arrhythmia causing symptoms or hemodynamic compromise (including severe bradycardia or tachycardia, sick sinus syndrome, or multifocal premature ventricular contractions) * Presence of any clinical condition that makes the patient unsuitable to participate in the trial, e.g., significant ischemic or valvular heart disease, cor pulmonale, unstable coronary artery disease, primary renal (e.g., estimated glomerular filtration rate (eGFR) \3.0 times the upper limit of the normal range), pulmonary, neuromuscular, orthopedic disorders, among others * Inability to exercise on the treadmill * Inability to provide informed consent * Concern for inability of the patient to comply with study procedures and/or follow up (e.g., alcohol or drug abuse) * Any contraindication to heat therapy and/or inability to fit into water-circulating trousers * Impaired thermal sensation in the leg