Heart failure (HF) is the #1 reason for hospital admissions. About half of the patients with HF have a preserved ejection fraction (HFpEF). There is no targeted evidence-based treatment for HFpEF. We recently reported that elevating the heart rate with pacemakers conveys clinical benefits e.g. reduction in heart failure symptoms, lowering filling pressures and an increase in walk distance. Cilostazol is a PDE3 inhibitor that increases the heart rate by about 5-8 beats per minute and has other potentially beneficial HFpEF effects such as peripheral vasodilation, lusitropic effects and dromotropic effects. By activating proteinkinase A, cilostazol may also phosphorylate titin, which may reduce myocardial stiffness.~n-of-1 study design using the standard dose cilostazol formulation of 100mg twice a day approved for peripheral vascular disease. The investigators and patients are blinded. The patients serve as their own controls with two crossovers (Week 1: cilostazol or placebo - Week 2: placebo or cilostazol - Week 3: cilostazol or placebo - Week 4: placebo or cilostazol).
Determine if cilostazol improves symptoms and NTproBNP levels (heart failure blood marker) in heart failure with preserved ejection fraction (HFpEF) - a prevalent syndrome without targeted evidence-based treatment.~This will be assessed in a prospective 1-month single blinded study with 2 cross-overs n-of-1 study design with placebo and cilostazol