 Heart failure with preserved ejection fraction HFpEF is a leading cause of mortality in the elderly. Outcomes of patients with HFpEF are poor and so far, no treatment has been shown to decrease morbidity or mortality. Recent animal and human studies suggest that a systemic proinflammatory state, produced by comorbidities, including aging, plays a central role in the development of HFpEF, supporting the notion that attenuating the proinflammatory state is an attractive therapeutic target for HFpEF. We have previously shown that low-level transcutaneous electrical stimulation of the vagus nerve tVNS suppresses inflammation in patients with atrial fibrillation. The overall objective of this proposal is to examine the effects of tVNS on diastolic dysfunction, exercise capacity and inflammation in patients with HFpEF. Our specific aims include: 1. To examine the effect of intermittent 1 hour daily for 3 months tVNS on diastolic dysfunction and exercise capacity, relative to sham stimulation, in patients with HFpEF and 2. To examine the effect of intermittent 1 hour daily for 3 months LLTS on inflammatory cytokines relative to sham stimulation, in patients with HFpEF. The proposed proof-of-concept studies will provide the basis for the design of further human studies using LLTS among populations with HFpEF. In light of the increasing number of elderly patients with HFpEF and the poor success of the currently available treatment options, an alternative and novel approach such as tVNS has the potential to impact clinical practice and improve health outcomes among a large number of patients. It is anticipated that these investigations will contribute to the broader understanding of the role of inflammation in the pathogenesis of HFpEF and how its inhibition can be used to provide therapeutic effects. Moreover, it is anticipated that a better understanding of how modulation of inflammation affects one of the hallmarks of HFpEF, diastolic dysfunction, will lead to the development of novel pharmacological and non-pharmacological approaches to treat this disease. 